Hot water diversion is now more affordable with the new Catch Power ‘Green Catch’
Hi everyone. Happy New Year! This is a short article about a new hot water diverter developed by Australia’s Catch Power. I’m just letting you know it’s available and because I don’t really have anything bad to say about it this may seem like an advertisement.
Regrettably, I have little choice other than to write articles that read like ad copy now that Finn has fired me for writing the word “megawatt-hour” when I should have written “megawatt”.1 Little choice, that is, if I want to score a new job in advertising! Specifically, on Madison Avenue in New York. I saw a TV show and there’s an agency there where everyone is totally retro and they all dress like it’s the 1950s. I could totally see myself working there.
If I shaved this is exactly what I would look like in a suit.
Advertising companies need people who enjoy pointing out flaws in products, right?
What’s A Hot Water Diverter?
A hot water diverter is a device that sends surplus electricity from your solar power system to your hot water system. This saves you having to use expensive grid electricity to heat water, although it will cost you the feed-in tariff you would have received if the solar energy had instead been sent into the grid. This means they are no good to you if you are still receiving an old high feed-in tariff. This article goes into more detail on diverters, this article compares different types, and here is our Diverter Comparison Table.
If a home has a solar power system of 5 kilowatts or more it is possible for a diverter to allow over 90% of the electrical energy the hot water system uses to come from rooftop solar, although the exact percentage will depend on location and hot water consumption habits.
If
- your solar feed-in tariff is considerably lower than what you pay for the grid electricity your hot water system uses (which could be a controlled load or off-peak rate) and
- your hot water consumption is high enough,
then a diverter can be an effective investment.
The New Green Catch Diverter
Catch Power produces a Blue Catch diverter, but their new product is a more compact and lower cost version of their Green Catch diverter that used to look like this:
Oh god! So ugly! Avert your eyes!
But now it looks like this:
Yeah, that looks a bit better.
However, the above picture doesn’t give a good impression of the true size of the device:
Oh my ghawd! It’s so cute!
Tech Specs
Below are some technical specifications taken from a brochure you can see in full here:
The maximum hot water system heating element you can use the Green Catch diverter with is 4.8 kilowatts. Most hot water systems have elements that size or smaller, although there are exceptions.
The warranty is 5 years, which is a lot better than the 2 years some diverters have.
Price
The new Green Catch diverter has a Recommended Retail Price of $680. This is a considerable improvement as Catch Power previously told us the installed cost of the ugly old Green Catch was $1,000. Getting a qualified electrician to install a cute little new one is likely to cost over $200 and Catch Power has told me the typical installed price is $850 to $900. Hopefully, as this diverter becomes more popular, the installation price will come down or at least be at the lower end of that range, as practice make perfect. Or at least faster.
Western Australia Is The Best Location
The best place to install a hot water diverter is Western Australia because:
- there are no longer controlled loads available to reduce the cost of operating electric hot water systems and
- WA’s solar feed-in tariff is only 7.1 cents.2
But the following conditions are important:
- An electric hot water system is required instead of the gas hot water most WA homes have.
- A home or business should be on a standard tariff that charges a fixed amount for every kilowatt-hour of grid electricity used rather than a time-of-use tariff that lets hot water systems use lower cost off-peak electricity late at night. A standard tariff is usually better for solar homes.
Somewhat offsetting the value of a hot water diverter is the simple fact Western Australia doesn’t get that cold, limiting the amount of hot water people use. But even a household with modest hot water use can benefit from a diverter. If a two person household has the following characteristics:
- They use an average of 4 kilowatt-hours a day for heating water.
- They have the Synergy standard tariff that charges 28.3 cents per kilowatt-hour.
- Their solar feed-in tariff is 7.1 cents.
- They have a solar power system of 5 kilowatts capacity or more.
- A diverter will allow them to get 90% of the electricity their hot water system uses from their solar system.
In this scenario the household would save:
- 76 cents a day.
- $279 a year.
- $1,393 over the 5 year warranty period of the Catch Power Green .
So even if the Green Catch diverter died the day after the end of its warranty — which it hopefully won’t do — they would still be almost $500 ahead even if the installed cost was $900. If it keeps working just a couple of years past the end of its warranty the household will be over $1,000 ahead.
It seems like a no-brainer. Especially for larger households with higher hot water consumption, which can have far higher savings. However, having a diverter installed needs to be compared to the cheaper alternative of putting the hot water system on a timer that switches it on during the day. The effectiveness of this approach varies with the size of the heating element. Smaller elements are able to use a higher portion of solar energy as they are less likely to draw more than the available amount of surplus solar power.
If we assume the following:
- Having an electrician install a hot water system timer costs $200.
- The timer enables the hot water system to get 50% of its electricity consumption from rooftop solar.
- Everything else is the same as in the example above.
Then the household will save:
- 42 cents a day.
- $155 a year
- $774 after 5 years.
In this example, thanks to its low cost, the household can be better off with a timer after 5 years. But a diverter doesn’t need to operate much longer for it to clearly pull ahead. While it will depend on the individual circumstances, a Green Catch diverter will often be the best choice by a wide margin.
A Queensland Example
Hot water diverters can pay for themselves outside of Western Australia, but a household may need to be a large user of hot water for it to be worthwhile. I’ll give an example of what kind of savings can be expected for a two-person household in rural Queensland since I happen to have the electricity bills for this kind of home in front of me. This household has the following characteristics:
- It uses only 3 kilowatt-hours a day for hot water because the climate is even warmer than Perth’s.
- The hot water system is on a controlled load called Tariff 31 that is 19.2 cents per kilowatt-hour.
- Grid electricity is 27.8 cents per kilowatt-hour.
- The solar feed-in tariff is 9.4 cents.
- It is assumed 90% of the hot water system’s electricity consumption will be solar after the diverter is installed.
Under these circumstances a hot water diverter will save the household:
- 18 cents a day.
- $66 a year.
- $331 over the 5 year warranty of the Green Catch diverter.
If the Green Catch diverter lasted for 10 years — twice as long as its warranty — it still wouldn’t save this household money. If the household was larger and used twice as much hot water while keeping everything else somehow stayed the same, the diverter’s simple payback period would be 6 to 7 years.
Because the cheaper tariff 31 is available for hot water systems, using a timer often won’t be a better option than using a diverter.
The Future Of Diverters Looks Brighter
While the advantages of PV diverters aren’t nearly as clear outside Western Australia, under the right circumstances they can still save money. The decrease in the price of the Green Catch is likely to improve its popularity and Catch Power should be able to make plenty of sales in WA. So I’m thinking the future of hot water diverters is brighter than it was.
Unfortunately, now that I’m unemployed, my own future is looking pretty bleak. With no way to pay rent to my ex-wife, my children will be soon be thrown out into the snow. (Finn is having some snow specially imported for them to be thrown into.) My only hope is for some kind of New Year miracle — such as my being sacked turning out to be just a low grade running joke I’m refusing to let go of. I sure hope this turns out to be the case because I don’t actually want to work in advertising. Who would want to go to a drab, soul destroying, advertising office like this everyday?
About Ronald Brakels
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Or, you can go with a pure solar hot water heater. I have one here in Mexico where they are very popular. Cost about 400 u.s. dollar equivalent installed. They have two types, one for pressurized systems or like mine that is gravity from a roof tank higher than the heater. It has way hotter water than a gas heater and the insulated tank is way larger. Four people can take a hot shower day or night. It produces acceptable hot water even on overcast days.
I have had electric, gas, instant on gas heaters and by far this one beats them all hands down. Saves me 35 bucks a month on gas, paid for itself in one year and still rocking on.
I think the cost of relocating to Mexico every time I want a shower would somewhat negate the savings!
Pure solar HWS are reasonably popular here, but relatively expensive. If I had a conventional electric HWS, installing this diverter would likely be a lot cheaper than a pure solar HWS – even allowing for some extra PV panels.
However… I already have a pure solar HWS, and a premium feed-in tariff, so no diverter for me.
I have a friend with a new solar PV system (no premium tariff) and an electric HWS, so this diverter would likely be a good investment in that situation.
Not being argumentative at all, but it seems a one or two year pay back schedule beats a five to seven hands down. One thing they do here that seems not to be fair is you are allowed 500 kw in a TWO month period, then your electric bill quadruples. And, to top it off you have to stay below the 500 mark for one year for your bill to drop down to the lower rate. I have 4200 watts of panels, grid tied and a battery back up system with inverter. What they do here is you can accumulate kwhrs if you generate more than you use, BUT, on the first of January they erase any accumulation and you start over. I am losing 1100 kwhrs. this round. Reading comments from folks in other countries seems to indicate that no matter where you live they write the rules to profit the power companies to the extent they can get away with.
They tried (CFE) to eliminate the accumulation of extra kw’s generated and zero them out every month, but the large solar companies took them to court and got a ruling forcing the power company to restore or rather just honor the contracts we all had to enter into when we installed panels, had to buy the special meter, get approved yada, yada.
Nothing like changing the rules after you sign a contract. Ah, the thrills of living in the third world.
OK… if I could buy a pure solar HWS for $400 it would be an utter no-brainer. Here in Western Australia you can tack another zero onto the price (unless you know a guy who knows a guy…).
I am amazed at the price of pure solar hot water heaters quoted in the replies above in Australia. Looks like a business opportunity for someone there to start manufacturing them and selling for a quarter of the current price and making a killing. Or, are there some kind of Gov. regs that prohibit? Also, i am installing another 5 plus kw’s of panels and simply forget accumulated kw’s or how much I burn. Zero electric bills now and into the future. I can heat, cool, cook and just live without worrying about electric bills. Sure it costs upfront now, but then just forget about rising tariffs, costs per kw. etc Simplistic, yeah, but it works for me.
(Note I am serial commenter “Scott” and not someone from Catch Power who is also commenting on this thread under the name “Scott” – I have no vested interests in HWS or diverters)
How about less than $1,000.00 installed? Would that get your interest?
(This “Scott does have a vested interest in CATCH…).
Hi,
I have been in favor of using a ‘standard’ HWS powered by solar for some time now. I built 2 of units in Lismore (NSW) with 250L HWS, powered by a simple time switch set to turn on at 10AM, & off at 14:00. These 2 units are using at last bill, 6KwH/day grid import for the total unit! I am still exporting power that gives me a credit overall. (Using Enova Energy 16c Grid feed: Great plan for non-Metropolitan NSW)
I fitted 2.4Kw elements to the HWS, then plugged the HWS into a power point (Wired at the build time). This allowed me to use a simple timer that is plugged in. (Make sure it is a solid state switch, not a relay contact for reliability)
The advantage of using ordinary HWS is they can be installed close to the Hot water users. It is even possible to have separate systems for the Kitchen & the rest of the house if the pipe runs are long to reduce water wastage. The heat-pump style HWS are much more efficient, but are installed further away from the users as well as being ‘mechanical’ so eventually they will fail. In my case the TCO of a cheap, easily replaced HWS that is reliable makes much more economic sense.
regards, Doug
I want to use a wifi timer so that i can boost it easily but is hard to find the right one.
Any suggestions.
Old thread I know but the Meross timers I have for pool pump, bore pump also measure power used. Very easy to set up, compact and the most economical I could find
CATCH Solar Relay is a smart switch that offers the control you are looking for.
Have been thinking of this, but it’s not sensible in Canberra (20 cents/kWh from grid & 8 cents/kWh FiT). But am looking at upgrading my Plugin hybrid EV to full EV. came across a Zappi EV charger from Myenergi which can be set to use surplus solar to charge car & the topup with off-peak overnight. But They also market a diverter for under $1000 that apparently does the same thing (using surplus solar topped up with off-peak) for 2 heavy draw appliances: EV, hot water, pool pump, etc. I think the warranty is only 3 years though. Would be good to see this reviewed if you have time.
The Zappi EV charger looks interesting.
Note the Eddi diverter, like diverters in general, will only be able to send current to heating elements such as those in hot water systems or perhaps under floor heating and can’t be for devices with motors or electronics. It has a warranty of 3 years. It can handle two heating loads, which will be useful for some applications.
Hi Ronald,
Is there any of the currently available solar energy diverters that’s appropriate for EV charging? Any suggestions?
Hi Marc
The power supplied by hot water diverters is only suitable for heating elements such as those found in hot water systems or perhaps under floor heating. It can’t be used for anything with a motor or electronics and so they aren’t suitable for electric cars.
What you can get is a smart electric car charger that uses a sensor to detect when your home is exporting solar power and charges your electric car only with surplus solar energy.
There are other ways to do it such as using a Fronius or other relay:
https://www.solarquotes.com.au/blog/using-fronius-inverter-smart-meter-relay-make-solar-electric-hot-water/
But if you already have a solar system and are getting an electric charger buying a smart one may be the best way to go about it.
I am speaking a non-expert here,
Modern inverters are being billed as having a communications link.
It claims to be Modbus RTU (RS-485) using a Suntec Aliance Data Map.
I can explain how Modbus RTU works but in essence it is a 2 or 4 wire communication link.
So if you have a smart EV charger that uses the Suntec protocol variant, it could be as simple as wiring half a shielded CAT5e cable between the 2 devices.
They may also communicate over Wifi.
This could also be VaporWare and we are looking at a market opportunity for someone to take a Rasberry pi and a couple of HAT modules and make make one.
Hi Ronald….The Fronius Smart Meter allows diversion of excess power to Hot Water also. How does this compare? Also if retailers get wind of any such diverters I understand they disconnect off peak circuits anyway.
A hot water diverter can send very small amounts of surplus solar energy to a hot water system, but a Fronius smart meter plus relay can only turn devices on or off when solar output reaches a certain level. So on a cloudy day a diverter could still send small amounts of surplus energy to a hot water system while a Fronius relay won’t be able to effectively make use of the small amount of surplus solar power that is produced. I wrote (poorly) about it here:
https://www.solarquotes.com.au/blog/using-fronius-inverter-smart-meter-relay-make-solar-electric-hot-water/
Electricity in Canberra is only 20c/KWh??
Why am I not surprised?
Yeah, it should be cheaper than that. Most of Canberra power is from Snowy Hydro, whose production costs have hardly changed in recent years. But they can now sell at great profit into the eastern grid with their reliable base load power, so we pay a lot more.
[Btw I think I’m paying about 20c/kWh – but the advertised consumption price here is just over 25c/kWh plus a 97.5c/day supply charge. With 25% discount on consumption (but not supply) to complicate matters, so it took me ages to do comparisons with other suppliers with different consumption charges, supply charges and discounts]
Maybe worth considering with off-grid PV installations which generate considerably more power than is used during the middle of the day. A question that would need to be addressed is just how efficient a storage hot water system is in terms of keeping the water hot for hours. I’m currently using an instantaneous gas arrangement which goes through a single cylinder per year, so I’m not exactly under pressure to change anything, but then ‘free’ water heating which doesn’t subsidize the likes of Origin is always attractive. The ability to tell the establishment / big business to go do something physically impossible has value to me that transcends a normal cost-benefit calculation.
My feed in reduced to 10 cents and the off peak water heating increased to 29 cents so I decided to determine the optimum period of solar generation from my system and divert that to water heating by having the off peak disconnected and placed on the main meter. A timer was installed on the water heater circuit breaker. The cost of a timer was $250 and installation one hour by the sparky.
So for under $400 my water heating is covered by solar generation. The timer has a control dial so I can alter the on and off times when the seasons change – a simple one minute job.
Let’s hope this new model actually works and diverts “surplus” solar energy because I have had a Blue Catch Power system for over six months and it does not divert ‘surplus’ electricity. Instead, it continually diverts until the thermostat cuts in, meanwhile I am importing more power from the grid than I did without the diverter. I believe it is costing me money. The technology either does not work, the unit is faulty, or it has been incorrectly installed. The unit was installed last June. Within days I brought the funny numbers to Catch Power’s attention and seven months later I am still waiting to have it fixed. It has wasted so much of my time that I would be happy if they just remove it. At this stage of my experience, I would NOT recommend a Catch Power diverter.
I appreciate the heads-up regarding the lack of interest in support. That is an immediate deal killer for me. Far too many companies want to flog gear and immediately lose interest in the moment it walks out the door. Best response to that is to blacklist the company. A certain mob on the Sunshine Coast that sells re-branded Chinese gear at a big markup and isn’t interested in after sales support belongs in the same category.
Victor, I have an email from you dated 11th December. I responded a few days later that I would get back to you once I had time to digest the numbers that you sent through to me, just to clarify the “seven months of no action” comment.. It is true, you’ve had questions about the operation of the device since it’s install, and with each query I have been in contact with you.
At CATCH Power we pride ourselves on backing up the product and following through issues until the owner is satisfied.
Your post is not an accurate account of the course of your ownership and definitely not reflective of the experience of the vast majority of our customers. If a full refund is the solution that works for you, then we would take your lead, but you have never offered this as an option. Very unfair of you to voice it here without suggesting it to us directly.
Here is a thought!
Whilst every household wont have a pool, could this be used for pool heating?
Or am i overthinking this and running the pool filter on Off Peak (Control Load in Endeavour Energy) sufficiently offset by the NSW Feed in Tariff?
Should I
You should be able to run a pool heater off this diverter provided it is an electric resistance heater and not a heat pump. The pool heating element will also have to be 4.8 kilowatts or less. Whether or not it makes economic sense will depend on your how much your controlled load grid electricity costs, the size of the heating element and the size of your solar system. Heap pumps seems to have taken over from resistance heating for pools so in many cases it won’t be possible to use a diverter but a timer or a relay that only provides power when there is sufficient surplus solar power can still be used.
Hi Ronald,
i am in west Australia with a flat rate for imports of 28.75 cents per Kw and a FIT of 7.135 cents per Kw. There are only two of us in the house and we are home most of the day as we are both retired.we have a 80lt storage electric hot water system, which we have just had fitted with a 1200 watt element, it was 3600 watts before, on our roof we have a 6.625 Kw solar system with a 5 Kw Fronius inverter with data manager and a relay for the hot water system.the house load during the day is 500 watts. I have just set the data manager to turn on the hot water relay at 1800 watts and of at 1600 watts with a minimum time of 1 minute run time.i use pvoutput.org to track our usage, we did it this way as a smart meter and a power diverter would have cost about 8 times as much and therefore had a payback time longer than the warranty on the diverter, we are very happy with the setup and look forward to see how much it saves us in the next 12 months.after the first full month of having the new small element installed and using my Fronius inverters load management system to control it,energy imported from the grid has dropped by over 40% and my self consumption from the solar has gone up by the same amount,so we are importing on average now 2.8 Kw per day less for a total out lay for the relay and new element with fitting of $280 so the new system for heating our hot water my well pay for itself in about 12 months
If you have an electric heat pump HWS, then the ambient air temperature is also a significant factor in the heating efficiency.
For a heat pump HWS, you could just use a mechanical switchboard timer to disable the heat pump overnight and enable it during the peak hours for solar PV and ambient temperature – say 11am to 5pm.
Hi Ronald
I haven’t heard much in the way of analysis of Solar HWS.
Here in Perth I very, very seldom need to electrically boost the system, between about mid-September, through to late April. In fact the problem for us during summer is to pevent the system from boiling over – achieved by covering 50-60% of the panels. The booster is permanently switched off.
For maybe 3-4 months of the year, our timer can be enabled when occasionally required, to use excess PV during the day. I guess we will (very occasionally) need to import power – as will a diverter – on really gloomy days, or when hot water is needed early.
I know Solar HWSs cost more than electrical HWS, but they typically last for 20-25 years (with minor service) – and I understand their efficiency for thermal energy recovery is vastly greater than using PV.
Hi Ian
The efficiency of a solar hot water system is higher than using solar panels and an electric hot water system, but it is actually possible to get higher efficiency by using high efficiency PV panels and a heat pump hot water system, as I mention here:
https://www.solarquotes.com.au/blog/efficient-hot-water-system-solar-pv-powered-heat-pump/
Although if there is room on the roof solar panels plus and standard electric hot water system can be cheaper.
But given that people in WA people are much more limited in how much solar PV they can install than in other states a solar hot water system can be a good idea for people who want to make more use of solar power than they are permitted to.
One important issue (I think Finn mentions this in his book) is that the cost of a solar thermal HWS is, and has long been, surprisingly high – considering the lack of rocket science that goes into making one.
Mike in Mexico (commenting above) suggests that they are an order of magnitude cheaper over there.
Any idea if this is correct, and why? I expect a few factors like economies of scale and more competition come into play, but should these account for such a large difference?
There are a number of reasons why solar hot water systems are more expensive in Australia than other countries. I’m not familiar with Mexico, but I know they are much cheaper in China where they are very popular. There are several reasons for the price difference.
First there’s is the cost of labour. It’s more expensive to get the installation and plumbing done in Australia than most countries. Australian standards prevent many low cost solar hot water systems from being sold here. (Some people say Australian standards are too restrictive.) And then there is the cost of transport. Even if a foreign made solar hot water system meets Australian standards an empty water tank takes up a lot of room and costs more to transport than its weight would suggest.
I am currently in analysis paralysis on this one.
I got into this mess because I have an ailing Gas Hot Water system that needs replacement. I have spent weeks back flipping between on-demand gas or a Solar HWS
Gas requires a large bore 25mm line to feed the beast.
Solar is pricey, has a relatively short warranty and winter electric boost expenses in the order of $250 pa.
I got caught in an up-sell and have decided to get a PV system. which sways the economics to an Electric Boost Solar HWS.
Much like the article says, the cheap and cheerful solution is a timer – Let the Thermal cut-out do the thinking.
It isn’t perfect, and I think I can do better, and cheaply but I need to get it right:
The Energy management System built into the Fronius inverter and Solar Quotes recommendation to spend extra on a quality make it a very attractive, and possibly obvious solution to my requirement.
https://www.solarquotes.com.au/blog/using-fronius-inverter-smart-meter-relay-make-solar-electric-hot-water/
But here is the catch, I need to know how (if) it will work to give me a hot shower when I need it.
There is a mention of it in the diverters chapter. It is all about how you can guarantee a hot shower without wasting valuable daytime PV generation. It feels like a game of chicken.
Advice so far: Know my usage, Keep it simple.
Summer is easy, In WA there is so much sun, the tank will be bubbling away like a kettle, boost will be rare and will be covered by PV.
Winter is where the clever thinking needs to be done.
Showers in my house happen between 5 and 7:30 pm, so my goal is to have a full tank of 60 degree water by 5pm each day.
My thoughts:
1. Use the Sun
2. Use the Fronius to control heating water whenever there is PV energy available, up until 3pm.
3. Run a Timed ($ Grid $) boil From 3 until 5:00pm to guarantee hot water.
4. Thermal cutout will stop power draw when the temperature has been reached
5. I think the Fronius is smarter and can track total active time, managing a shorter Grid Boil. This is a bonus, but I won’t count any chickens.
Case 1: (no Sun) 2 hour grid boil: Heating element gets tank to temperature in 2 Hours.
Case 2: (Mild sun) PV and the Sun Team Up to give me >60 Degree water by 3pm.
Case 3: (Full Sun) PV gets the tank to 60 Degrees quite early, Sun then excess -boils the tank. Some grid regen loss. Not ideal but not too bad.
Case 4: (Cold Morning shower) How much heat do I lose overnight?
Case 5: (Out of Hot water) – Log into the Fronious and switch on boost, wait.
My remaining challenge is to scale the Boost element in the Solar HWS
I am planning a 6.6 kW PV system, but being realistic, I am budgeting for 3kW Winter production.
Too High, and I will be pulling grid power, a slow boiling 1.8 kW is a good economic solution, but I don’t want to have to wait for my shower. My gut is telling me to match a 2.4 kW element to the available power
Any thoughts or experiences anyone can add to this?
Is a 3rd party diverter going to do much better? A tank temperature sensor and weather forecast are the missing parts to close the control loop.
I’ve owned two solar HWS on two different houses – the first close-coupled (thermosiphon, tank on roof) and the second split (pumped, tank on ground). Experience with both has been generally positive. One thing I’d suggest is that if you have a decently sized system then cold showers in the morning should not really be an issue. The insulation in the tank works much better than I expected it would.
I’d favour morning showers since that leaves you with a colder tank to maximise energy collection through the day. A good boost at night (if there hasn’t been enough sun) ensures hot showers in the morning.
Both systems pump out plenty of hot water, though I think the roof tank is a little more reliable (I needed the pump serviced after a few years on the split).
Good luck!
Scott, Thanks for your insight.
Yes, I have steered away from the split system. Less parts = Less parts to break down.
Your morning shower logic is sound, but if you’d met my family, you would understand why afternoon showers are a must. Active Teenage boys need to wash, and wash often.
In my scenario, I will be using my hot water in the afternoon and be left with a tepid tank until the following day, when there is sunlight to heat the collector or activate the PV.
I am curious to know if there will be enough heat left in the tank for one last morning shower before it is untenable.
There is a legonella danger in not boosting the tank. I figure that running a late afternoon boost is the solution – if it is already hot enough, it won’t draw any power
How do you know when a good boost is needed? Is it a manual process?
This is where some of the diverters excel, they look at the weather forecast and apart from being able to run an element at fractional power, can look at the weather forecast. Some also take a temperature sensor input from the tank.
The timer is a fairly simple mechanical device, installed in a switchboard slot, allowing selection in 15 minute increments. If you were concerned about having a cold shower in the morning, you could set a shortish boost in the morning?
Using the majority of the water in the evening (though understandable) probably isn’t the ideal use case – if you fully boost the tank after that, and use only a little in the morning, then you start the day with a hot tank. Of course you have readily available hot water, but you are not making as much use od the free solar heat.
Water needs to get to 60 deg C to kill legionella, a timed boost avoids this by enduring that this happens even on cloudy or cold days. On hot days, the sun should raise the tank temp well above this, in which case the thermostat will switch off tthe booster and avoid wasting electricity.
As long as the power to the booster is on, the thermostat will also start boosting any time the tank is below 60. This is why a timer is preferred – why do this at 8am when the sun is about to do the job?
Having typed all of that I can start to see the appeal of a smart device that does the thinking – rather than me trying to run game theory on boost optimisation!
Yeah, I was originally going to use a timer too, But when I found out that the Fronius has an intelligent timer built in and it is also clever enough to boost only when energy is available. I need to buy an inverter for my PV anyway and I was planing to buy a quality one, This is a bonus.
The one drawback is that, unlike a timer, it only has 1 timing range, and won’t be able to do a morning pre-heat.
Evaluating my expected usage has made be think that I might be sacrificing convenience for cost. I want to be sure that I can make it work before I go ahead.
It is this reason that I am considering gas boost solar or maybe even throwing my toys out of the pram and being an environmental vandal just going for an instantaneous Gas. I can run it for $100 per year more than the solar and it is 1/2 the price.
My FIT is higher than my off-peak hot water tariff. No further assessment required in my case.
But for those where the tariffs are the other way round I still struggle to see many scenarios where the high cost of a smart switch will be worth it compared with a far cheaper and simple “dumb” timer set to heat water during hours where the household *typically* has the most excess PV production. Use a HW unit with a lower power heating element for homes with modest sized PV systems.
Only have to calculate the upper limit of potential savings using solar PV to heat HW to see the problem:
Upper limit of savings = annual HW energy usage x (HW tariff less Feed-in tariff)
e.g. if you use 2500kWh/year to heat water and the difference between your HW tariff and FIT is $0.06/kWh, then the upper limit of savings from using excess solar PV is $150/yr.
A smart switch might perhaps capture 10-15% more of those savings compared with a simple timer. That means a smart switch will save perhaps $15-20/yr more than a simple timer. But if a smart switch costs $600 more than a simple timer, well it’s just not worth it. $600 / $20/year = 30 year payback.
It’s the same scenario for my pool pump, which is set to operate during times where typically I’ll have sufficient excess solar PV output. Yep, sometimes I won’t have that excess PV power available and it’ll need to draw from the grid as well (cloud cover and/or when we happen to use another high power device at the same time) but such differences in grid energy draw are quite small such that a smart switch won’t be able to justify its high cost.
Hi Alex
Ronald did say that things would have to be fairly ideal, for the option to prove economic.
However – in Perth – and Ronald did give this as an example – I pay 28.3272 cents per unit tariff, and have a 7.135 FIT – difference is ~ 21 c/unit – so in your example the upper limit in savings is (21/6)*$150 = $525/year, so less than a 2 year payback.
However in my case, we already have a solar HWS, so most of the year we pay $0 for electrical water heating. In winter, we also have a “dumb” switch – me – we leave the booster switch OFF, until our more recent PV is developing enough to cover the extra load. In actual fact, our booster switch also has an “AUTO” mode, which allows a timer to switch the booster as you have suggested – but we very seldom have occassion to use this.
Same goes for the pool pump – which has a variable speed drive and only draws ~ 700W when running – the timer for this, and for our lawn irrigation system (from a 3 kW bore pump), are also set to only run when other house power draw is low, ans the normal PV generation is high.
The only time I really pay for imports is overnight – to run lights, entertainment, and refrigerators – plus boil the odd kettle of water.
Where we some have difficulty – for only a small part of the year, is running the bore pump during the shoulder seasons – our water restriction rules require irrigation to be completed before 9am. In summer we are usually producing 4kW when needed – but less than 3kW in the shoulder seasons. However, even a diverter couldn’t help much with this – instead I shorten the watering time (less water needed, anyway), and set the timer to switch on in time to time out by exactly 9am. Only happens 3 times a week. I have contacted our Water Utility about relaxing the 9am cut-off in the shoulder seasons – as evaporation is less and occurs later – and they have forwarded my email to a higher authority.
So, yes Alex, I think a simple timer can deal with, and provide near optimum savings – if you are willing to make adjustments – mine works off an irrigation timer, driving 24Vac coil contactors.
Hi Ronald,
I am now in the process of getting quotes for a sanden heat pump. I have a question though.
I am considering keeping my 315L 4.8kw heater, replacing the element with a smaller 2.4kw and using something like this diverter to pre heat water before the it enters the sanden. I live in the hawkesbury NSW, (yet to install the solar mind you, getting quotes on that also).
Aesthetics don’t bother me but do you think this is worthwhile?
Good luck job hunting, love your articles!
Many thanks,
Tim
Hi Tim
Just considering the economic return, if your current hot water system is on a controlled load then you may be better off keeping it on that and using the money you save from not altering it or getting heat pump hot water to invest in a larger solar system. Later, when your current hot water system needs replacing, you look into getting a heat pump.
But if you are getting a Sanden heat pump hot water system, because it is so energy efficient there will be no benefit to preheating the water. The Sanden should use around one fourth the amount of electricity to heat an identical amount of water to the same temperature as a standard electric hot water system. So any electricity you use preheating water in the conventional way will cost you more than letting the heat pump do all the work, whether that energy came from your solar panels or the grid.
Ronald,
Apologies, I must have signed up to get every update to every comment for every topic on the solar quotes forum which within 5 minutes was very tedious so I cancelled that, and missed your reply, which was exactly what that other bloke Gabriel Brady had replied to me in email.
Thank you both for your patience with the likes of me.
Still waiting on a couple of quotes however hope to have solar on soon.
Best regards.
Tim
Hi everyone
In October 2018 we installed a 4 kw solar system (in Melbourne) and was repeatedly told by AGL to leave the HWS on at night in order to take advantage of the reduced controlled load rates. It was stipulated FIT would be $0.117 and controlled load $0.19. Hence no great saving in having the HWS run off the solar panels during the day.
However AGL failed to check that the distributor (United Energy) does not allow for FIT and controlled load (it is one or the other) and when the smart meter was reconfigured they even forgot to mention this to us. Consequently we have not knowingly paid full price of $0.29 for the HWS that continues to run at night without controlled load. The ongoing case has been referred to the Energy Ombudsman with AGL continuing to be extremely difficult!!
That said I would assume a HWS dumb timer or even smarter diverter would be cost effective considering the FIT is $0.117 and there is no controlled load discount but rather a standard price of $0.29.
Has anyone else experienced anything like this?
Rocco
An overdue update. AGL came back and paid for a new Catch Power diverter which seems to work well. Happy with AGL although it did take a lot of perseverance (cursing) and the Energy Ombudsman!!
Hi everyone,
I thought of sharing with you two different types of hot water products.
The first of product is a diversion device from myenergi.com called Eddi, https://myenergi.uk/products/.
The second type are solar enabled devices such as the nectarsun from https://nectarsun.com/how-it-works.html.
The first type diverts renewable energy to the hot water tank.
The second type is an MPPT device connected to solar panels to heat hot water.
I hope either one may be of use to someone. I have not tried either one, and they both seem promising products.
Cheers,
Eric
In 1993 ,i use to get frost , so I got a Solar hart Hot water system fitted, it had Anti-freeze /Anti Boil inside the tubes and the water surrounds the tubes to heat the water . Today its just about rooted. I replaced the hot water valve about every 8 years (dies) and rarely wash the panel , as its a 26 degree roof and on stumps . I had a switch inside the bathroom , for the odd 3-5 day cloudy/ rain events .
Roger,
I am newly in the market and from what i have read the new regulations require that the tank is brought to a legionella boiling temperature every 3 days. The game has changed a little bit since ’93. I think it is 58 deg but most suppliers set their thermostats to 65 to cover themselves.
Hi Tim , have not had a plumber touch it since it was fitted . I paid a friend to change the hot water valves in the tank . Only changed about every 8 yrs .Its VERY HOT .
Sounds pretty normal, and a great advertisement for renewable energy.
The case that was pointed out to me is the few weeks during the dark of winter. The tank gets to a usable 45 degrees without boost, but creates the perfect environment for brewing baddies.
The other side of it is sheer laziness. If I go to the bathroom to have a shower, I don’t want to have to wait 2-4 hours before I can get clean, I don’t pay attention to the weather, so it will be too late by the time I work out it has been a cold day.
Second Part is that I want to minimise any power I use from the grid by using surplus power from the solar array.
On paper the green Catch is the perfect solution, even capable of supplying power less than the rated heating element. It is also great if you have an off-peak tariff, it will only use cheap grid power if there wasn’t enough PV during the day.
To give balance, it has some shortcomings. I have concerns purchasing a device with a clock that you can’t set.
I also believe that the ideal solution would have a temperature sensor on the tank and access to a weather forecast. Why boost if there is going to be enough heat during the day to get the tank to temperature, but it essential to boost if it isn’t.
On balance though, it is great value for money, the economic viability is based on the total amount of boosting you need to use during winter and if a timer will get you 80% of the savings. (PS it won’t if you have access to an off-peak tarrif).
Fronius have a nice solution built into their inverter, if you have one, They come at a premium price though,
Hi have had a Catch power fitted , i have a separate switch to turn off element in the fuse box it is turned off but the Catch Power still heats the water even whilst it’s been overcast and raining, it comes on during off peak early mornings, can you please send me a wiring diagram to use a switch to disable the element during summer and still use your Catch Power unit.
Regards Costa Gabriel.
Hi
I’m being paralysed by indecision and confusion on what to do with our HW. We are in QLD and have an electric HW system on tariff 33 using about 331 kW a quarter at 20 c/kw – which is hugely expensive. We have 5Kw solar and only get a feed in tariff of 7c/Kw. Our electric hot water system (250L) is around 9 years old but still working fine. So was looking at getting a diverter to reduce electricity cost (and if it breaks down just replace with similar one) but article suggests savings are not that great for QLD – $116 a year? but thats my water bill in a quarter! if diverters work as suggested, shouldn’t i be saving more than that? Or as i have roof space and the HW tank is old, should we just go a solar hot water system? – but this cost more. Any suggestions??
Hi Fiona
First off, you should consider if you’d be better off changing your electricity plan so you get a better feed-in tariff. You’ll probably be better off on one with a higher feed-in tariff. If you use an average of around 331 kilowatt-hours for hot water a quarter on tariff 33 than that will come to around 1,300 kilowatt-hours a year. If you have a 10 cent solar feed-in tariff and your hot water system is on tariff 33 which is 20 cents a kilowatt-hour and a diverter allowed all the electricity used to heat water come from your solar system then it would save you 10 cents a kilowatt-hour or around $130 a year. Because some electricity would come from the grid you might save around $110 instead. Whether or not it is worthwhile getting a diverter to save this much is up to you, but if you get a solar feed-in tariff that is over 10 cents it probably won’t be worthwhile.
You could consider taking your hot water system off tariff 33 and putting it on a timer so it will only switch on during the day, but this often isn’t an ideal solution either:
https://www.solarquotes.com.au/blog/solar-hot-water-timer/
You can put in a solar hot water system. In Queensland a lower cost flat plate system will do, but the savings from this may not be high either.
Hello Ronald,
After our solar panels & Fronius inverter was installed a local electrician procured & installed a ‘Green Catch Power’ unit.
It worked fine except for 2 things.
1. Every few days at 12.10 PM it switches to full grid power, regardless of production, for several hours. The instructions say it never does this unless overridden by the manual switches(I have since read your overview why it, in fact, does this).
2. When actually diverting power though the day, the house lights flicker, particularly the fluros & power-saver bulbs and the house fans vary up & down in speed.
My original hot water tank(no.2) is heated by off-peak & the new one(no.1) is connected to the diverter & feeds hot water to no. 2. This was to retain the off-peak option(thermostat set low) & no.1 set max. temperature.
Naturally one certainly does not want any grid power to no.1 at all! unless manually switched.
1. Is there any way of disabling the “smart function” that heats every few days?
2. Am I able to communicate with the makers of ‘Catch Power’about these problems?
3. Do you have an overview of the Fronius Ohmpilot – would it do the same kind of things?
Kind regards
Frank
Hi Frank
I am concerned your fans are slowing down when the diverter is in operation. It sounds like it is causing regular brownouts which is not good for appliances and can cause your solar inverter to either shutdown or derate and lower its output during the brownout. I recommend contacting the electrician you bought it from and Catch Power should also be able to assist. If it is faulty it has a 5 year warranty.
I don’t know much about the Fronius Ohm Pilot except that when I last looked at it the price was quite high. If its price has come down then it would make sense for me to look into its details.
I checked out the Ohmpilot 12 months ago and it then wasn’t available in Australia. It will be very expensive when available ($1500 plus instal) and only works if the inverter is within 10 metres of the HWS. I believe a new Fronius smart meter will work with a relay to achieve objective of using surplus solar power now. After blank looks from the solar people I opted for a timer switch which is an idiot proof solution and works for me.
Thanks for that.
Thanks Ronald.
I had a catch power green installed in a few years back with a 5kw system. It worked perfectly well until the first few cloudy days and self destructed when it used the grid I guess for the 1st time.
It was replaced and worked well except we had 2 elements burn out .. coincidence?? Then the power company replaced the meter and a few weeks later it blew up again and a ping pong match between the meter contractor, power company and catch power followed.
And I still don’t have a catch power…
I built my own hot water system with 4 second hand 250w panels and a small hot water service plumbed before the main one for around $600.
Installed a 10kw system back in July and couldn’t work out why our Fronius Solar Web readings were nothing like the readings on our power bill. Switched to AGL who has a fantastic interface, and was horrified to see that during the middle of the day we were exporting 5kwh to the grid every hour (export limited) and also drawing 4-5kwh from the grid at the same time. Crazy when we have a 10kw system. Realised it was the hot water on controlled load (totally newbie to it all). Basically a whole lot of extra power being generated which was being wasted whilst paying AGL to heat our water. Since getting solar installed I’ve become very anti-“put money into the pockets of the electricity company” when they pay a pittance for FIT so didn’t bother with the sums and just paid for Green Catch Power. Had it installed today and immediately had the satisfaction of seeing all that unused solar being used to heat our hot water. Can’t be bothered doing the sums but will be interested to see the effect on our bill.
Sounds like you are using a lot of energy for hot water so I doubt your diverter will have any trouble paying for itself.
We live in a rural area and pump from the river which has a lot of sand that seems to clog up the hot water system and make it not very efficient. Seems like our hot water system is using around 15-20kwh per day so it’s gratifying to see now that our Catch power has been installed that our self consumption is sitting at around 60% whereas before it was more like 15% and our self sufficiency is now at 83% (we are only drawing 17% of our power needs from the grid.)
Glad to hear your Catch Power diverter is working out for you.
I write this review as a warning to anyone considering a Green Catch from catch power. I would like to spare other the frustrations and hidden expense that can be associated with the Green Catch.
I bought a Green Catch with my solar system, and initially it appeared to be working well, utilising solar to power my hot water system rather than the grid. Watching my energy usage painted a different picture. Every morning I could see that there was a period of solar export and grid import at the same time. Curious, I began isolating devices on the switchboard, finding this was the result of the Green Catch.
Eventually with evidence gathered, I approached my installer who attempted to follow up with Scott from Catch Power, and eventually I was speaking with Scott directly. Over months Scott asked me to leave this with him before he stopped responding all together.
What Catch Power doesn’t tell you is how this Green Catch functions, that it relies on a flaw in older smart meters to achieve “solar only” usage. In detail, solar diverters can function in a variety of ways to power devices. The Green Catch is a burst fire type device. For example, if you have 1500W of solar available and a 3600W heater, the Green Catch calculates part of a second to switch on for. In this example, something in the order of 0.4seconds each second (1500W / 3600W). In this way, it acts like a fast switch, and in effect it treats the grid like a battery of sorts. The problem is, for the 0.4 seconds it’s turned the hot water system on, it pulls the full 3600W. 1500W from your solar, and the remaining 2100W from the grid, costing you money if you have a newer smart meter which measures energy usage multiple times per second.
In my case, each day about 1 to 1.5kW of extra energy was being pulled from the grid on clear sunny mornings, worse on cloudy days (whenever less than 3600W of solar is available), sometimes pulling 3kW or more from the grid.
I’ve since returned my Green Catch, yet my solar installer is being refused a refund. For a device that can supposedly “heat your water purely from your excess solar”, well it’s certainly false in my case, more or less is false advertising. If my installer is able to get a refund down the line, I will edit this review.
Otherwise be very careful if you’re considering a Green Catch. There are better diverters out there.
We installed a Green Catch unit at the end of last year and we also discovered the same problem – despite having surplus solar we are still drawing power from the grid. The problem is much worse on cloudy days. Despite the advertisement that it draws power “only from surplus PV”, it demands using power from the Grid!
It was only after talking to our solar installer, who was baffled by the problem, and trying to contact catch power directly by telephone (wasted effort as no-one answers), I started googling for a possible solution and stumbled upon your comment. If only we had read this first I would have looked at an alternative diverter.
Currently we’ve switched off the green catch – it’s totally useless to us. We are relying on LPG back up. Did you have any success on a solution / refund? We’re waiting for our installer to get back to us – he’s probably waiting for someone to answer his call at Catch Power. We won’t hold our breath – think I’ve just thrown away ~ $1000 🙁
BUYERS BEWARE OF GETTING CAUGHT BY CATCH POWER!
Hi Geoff. Sorry, I posted my reply in the wrong section. Please look for it in the main thread.
I originally found out about the Green Catch through this Solar Quotes review, and I too had problems similar to Samantha and Geoff where my Green Catch was drawing power from the grid when it should have been diverting power from the solar. They way I determined this was my retailers daily graphs basically showed the same amount of power being imported and exported to the grid in each of the hourly blocks where the diverter was operating.
I emailed Catch Power including the information from these comments and that I was using a SolarEdge inverter with an Atlas MK7A smart meter. They let me know they were working on an undated firmware and shipped me a replacement unit about a week later under warranty.
Based on my inverter graphs and my retailer’s energy usage graphs the new unit and firmware appears to have fixed the issue and I’m no longer drawing power from the grid for my hot water. Now my retailer’s graphs show either almost no power being imported or exported, or excess power being exported in each hourly block.
Hi Geoff, I’m sorry that you’ve run into the same situation. I’m rather frustrated that these devices are still marketed as being able to divert only excess solar which they are technically incapable of with the type of operation. It’s only through flaws in meters that they act as a “diverter”.
I was offered a refund by my installer, and this is something guaranteed by Australian Consumer Law. That is, you are entitled to a refund. It is a major fault, and something that if known beforehand, would have stopped you purchasing the device.
I am aware that my installer has not received a refund by the supplier, so currently they are wearing the cost of this. I dare say they won’t touch the Catch Power devices again. And I don’t blame them.
I would encourage you and others (including my installer) to approach their Civil & Administrative Tribunal (eg NCAT) and make a claim for a refund. For a small fee, (eg $52 in NSW), assuming you can show evidence of the fault, you’re likely to receive the refund, assuming that merely the NCAT application doesn’t itself result in a refund.
Following removal of the Green Catch, I’ve been enjoying grid-free solar hot water through another device, the PowerDiverter, which does function as advertised.
Thanks Samantha for your reply. Having been burned once by these so called “diverters” that promise “only surplus PV” I’m now suspicious of their claims. I’m sure you’ve investigated the technical details of PowerDiverter and have observed it works as advertised. I’ve since become aware that there are different smart meters and that not all “diverters” are able to provide cost free hot water on all meters. Thanks for your recommendation and I’ll investigate as best I can.
Our installer came out to check our unit and he agrees it’s not doing what it should do. He has installed these units in the past but mine was the first he was made aware of the problem. That’s probably the case with most installers. Moving forward it would seem these units may become obsolete. It’s good to have our installer on our side. We can only hope Catchpower comes to the party before pursuing mediation. Maybe they already have research and development working on better tech…
It would also be good if solar quotes could re-review these diverters or at least provide a technical piece on the pitfalls of some of the diverters that rely on burst fire or PWM. Despite claims they don’t use grid power they actually do.
I suspect this problem is only going to increase in the future as meter providers/vendors and energy providers opt for more accurate meters such as the Atlas. I say more accurate as they measure multiple times per second into separate import and export tariffs, rather than aggregating it over a second or more (which the catch relies on). In terms of a fix, they strung me along for months. Given the mode of operation, it’s unlikely it will ever work with the more accurate meters.
I can only speak negatively of the green catchpower and the companiy’s inability to communicate properly. In addition to it not diverting as advertised, the internal clock is not adjustable and slowly shifts the time that it switches on for boosting. As a result it creeps out of the off peak time for optimal use and cannot be adjusted for any changes in off peak times. It also causes power surges when pulsing energy to the HWS and makes lights blink annoyingly in the house. Eventually it failed altogether but I had a dickens of a job getting catchpower or the installer (Cola Solar) to replace it. Neither seemed to understand the Australian Consumer Law. I still have it, but only use it as a solar only unit and put up with flickering lights. The service tech that finally came out (Johnoh) was great. Only bright light in the whole sorry saga. I’ve given up trying to exercise my rights under the law and put it down to experience.
I am about to come connect an ELWA device from MY-PV.
The is not a diverter; however, it shares a 1.8-kWh off-grid array with a DC solar air con. I have read good reviews on it.
MY-PV has three other products that when connected together with a compatible meter with CTs will work on surplus energy.
These other three products can detect a frequency change from the inverter when used off-grid to provide heat.
They are; however, designed to coexist with the grid. Thus they can work off-grid with an existing inverter or connected to the grid and an inverter.
There is a company somewhere that represents their products.
The manufacturer is from Austria.
I hope this helps.
Here is a video for the previously mentioned products from MY-PV:
https://youtu.be/kOah-GlxcCI
Keep in mind that unlike hot water solar collectors these systems will provide a reduced amount of heat in the winter from the PV panels.
Another difference compared to HWSC is that the boiler can be located far away from the solar panels.
Very glad I read this blog – I was about to purchase a Catch diverter, but has now decided against it. Looking at the technical data sheets on their website, I can see, as a professional engineer, that there is much left off that causes concern. For example, what is the idle power consumption ? What is the “PWM”frequency ? What is the EMS credentials ?
It borders on false advertising…..
Thanks to all who contributed to the discussion.
Am I missing something here, but don’t a lot of heat pump HWS have timers built in which allow all sorts of configurations? No extra cost or installation and in summer pretty much going to work as well as a diverter. Probably not as good in winter. No extra installation to go wrong either.
I’m a bit hesitant to add to this long blog, but thought I’d share our experience with the Catch Green Solar Diverter, that we had installed a week ago.
The short version: It does exactly what we hoped – diverts excess solar to our HWS in the manner described on the Australian manufacturer’s website. I’ve confirmed energy usage using both the Fronius smart meter data and meter usage exported from AGL’s website
The long version:
– We’ve always heated our water using Tariff 31 (super economy off-peak), which is currently 20.6 c/kWh from AGL
– We only use (on average) about 4kWh/day to heat water
– We have a large 250l HWS, dual element, both elements 1.8kW. Only two in the household, so the second (boost) element was rarely, if ever, used
– Our solar FIT plummeted from 20c/kWh to about 8c/kWh on average (10c for first 14kWh and 5c thereafter) which prompted us to explore diversion opportunities
– We have activated the SOLAR ONLY option on the CATCH green device (it’s not well explained in the user manual, but there are two SOLAR ONLY options! The first will heat at night using off-peak power if thermal cut-off isn’t achieved with solar power during the day, and the second will only use solar)
– It has been wired to conform with the Qld regulations, which don’t permit use of off-peak Tariff 31 power, and the power feed to the second boost element has been removed (we now have a single 1.8kW element HWS)
– Given we only use 4kWh to heat water / day and we export on average 20 kWh/day, we’re comfortable not to achieve thermal cut-off on very poor solar generation days (which is likely to be less than 5 days/year, although I’ve not checked)
– Given our small usage, the payback period is reasonably long – I’ve estimated it to be 4 years (it will be shorter if FITs go down)
– We’ve monitored power usage from both the energy company meter (using the data export tool from AGL) and data from our Fronius smart meter, and have confirmed the consumption and usage data aligns!!
Thanks for the insight into your experience, Jon.
Hey Ronald, how would these new relays compare from https://www.catchpower.com.au/product-page/catch-solar-relay
Hi Crossy,
They’re great devices but do a bit different job. Have their own monitoring portal and remote control app. Can also be used in pairs to act as an internet enabled switch or remote metering device.
https://www.solarquotes.com.au/blog/catch-solar-relay-review/
https://www.solarquotes.com.au/blog/catch-solar-relay-ships/
Hi Ronald
My Catchpower Green has been installed for two years. The internal clock has drifted and now heats from the grid 5am to 9am. The tank is full of hot water at 9am so cannot use solar power to heat.
Can the internal clock be adjusted / reset ?
I have a catchpower green (nearly 6yo) and from my exchanges with catchpower the clock cannot be reset or adjusted. It just drifts until it is useless. I reckon the ACCC should investigate at it does not do what it is supposed to do.
Ian Smith
Hi Ian,
Speaking from experience with Catch Power, whenever we tag Scott, Kathleen et al for some support they are really good, and it’s not just us. I’ve always found them to be highly responsive as an installer, and I have seen first hand the willingness they display when electricians reach out for help via various social platforms.
I know the GreenCatch has been updated, with an adjustable clock, so if you’ve had a warranty replacement are you sure it’s not one that can be reset?
The catch relay has been also been an excellent product from anything I’ve done with them or read from others. They’re Australian made and developed, they’re approved by DNSPs for network control and have agreements with all major inverter brands to run flexible exports control.
There’s a new 3 phase unit coming out soon and the whole industry is pretty keen on it.
I had been advised to purchase the Green Catch but I am concerned that the HWS will draw power from the grid at night when/if we shower whereas a simple timer in the line to the HWS can be set to only deliver power during daylight hours. I assume the cost of a timer and installation will be far less than the cost of the Green Catch.
Am I correct or is there another benefit of installing Green Catch rather than a timer.
Green catch will give you really fine control to harvest available solar for hot water, and unless you’re in Qld, it will also have a conventional off peak supply to it so you can have overnight boosting… or just switch that circuit off and rely on diverted solar.
Green Catch looks like a good idea but I am turned off by the bad experiences here, and the fact that it is not accessible by an app or able to be updated. Additionally it should be connectable to a system that can assist with predicting when it needs to do a preheat overnight ahead of bad weather – yes only as good as the forecast.
I could not see in the documentation if it would heat only until thermal cutoff and that is it for the day? (I read through the logic multiple times, only one thermal cutoff is mentioned).
Or if it would heat in the morning and cutoff at 11 when tank is hot, then say I use all the hot water by 12 noon, would it then heat while Solar is still exporting until a second thermal cutoff?
I love the ability to run from the offpeak if we have terrible weather for an extended period, but I need to know it will reliably give me solar PV powered hot water all day long on sunny days.
Lastly there needs to be certainty and guarantees that the meter issue and brown out issues have been addressed.
Would be great to hear back for sure in the next week by 10/5/24 as I will be finalising my solar install.
Thanks everyone for all the previous comments.
I visited the product review site where there are multiple comments about the hot water system using power from the grid when the catch power device operates. What I understand from the comments is that if there is less then the value of the element worth of solar it will boost it from the mains during the day at peak rates. That is 1 kw from solar boosted by 2kw from the mains for a 3kw element.
An installer also mentioned they stopped installing them due to a 25% failure rate.
Over to you for comment Ronald. I am hoping the afore said is false as it seems like such a good idea otherwise.
That’s not how a properly installed and configured Green Catch works – if there is only 1kW of surplus solar available it will only send 1kW to the element.
Of course there will be a small amount of energy pulled from the grid as the solar power jumps about and the green catch plays catch up – but in terms of kWh pulled from the grid, it should be negligible.
That is what I was originally told so that’s a relief. Looks like the people on Product Review don’t have the facts correct. Now for the issue of reliability. I have only seen this from 1 of your suggested installers. Do you know if there are reliability issues.
That isn’t quite how any of these solar diverters work, and certainly not the green catch. They operate using either a PWM (Pulse Width Modulation), phase control or burst mode (https://www.proactivetechnicaltraining.co.uk/energy-diverters-how-they-work-and-how-can-they-help-you-save-energy/).
From information Catch Power sent me, the green catch device I had (and returned) operates in a burst mode. This means, while switched on, your heating element pulls the full 3600W (or whatever your element is) for the brief duration, relying on aggregation or averaging in the meter to smooth that out. I’ve posted elsewhere how the Green Catch didn’t work with a particular meter because the meter samples many times a second. This is why I was seeing simultaneous feed in and usage.
After everything, Catch said they had an updated firmware to fix it, meaning they’ve worked out how to switch it on and off quickly enough to fool the meter. I’ve didn’t have the device at that time to test that update.
There are other devices which use PWM instead, which does a comparably better job of limiting the power delivered resistive loads like heating elements.
Yes – PWM or burst mode they achieve the same outcome as long as the sampling is fast enough.
Lets keep it simple for the less technical of us. Does it only use 1kw for a 3.6kw element if there is only 1kw of solar available or not. I don’t want to go to the expense of buying one to find I am drawing from the grid at peak rates.
Is there any information on the product reliability?
Hi Andrew,
You’re correct. Once the GreenCatch device sees 500w being delivered from your solar, and exported to the grid, it will introduce the HWS load to absorb that energy before it’s exported. The 500w threshold means it can properly measure before engaging the diversion circuit, but as I understand it, once they’re energised the harvesting is accurate to 10 watts.
The GreenCatch won’t allow you to use grid energy to heat water unless it determines the tank needs to be heated for legionella safety. This can be done with an off peak tariff (unless you’re in Qld)
Fronius have a diverter of their own called an Ohm pilot.
There are also other diverters available from Paladin(?) and more I believe.
https://www.solarquotes.com.au/hot-water/pv-diverters/
https://www.solarquotes.com.au/blog/solar-switchboard-upgrade-guide/
Technically no, the green catch does not modulate the amount of current delivered to your hot water system. It simply tries to turn it on for parts of a second so that the meter does not interpret any import. It’s like my induction cooktop which cannot deliver below 1000W. If I set it for 200W, it simply turns on and off quickly enough to try and achieve the same thing, even though it delivers 1000W+ while turned on.
PWM diverters achieve this by very rapidly (up to thousands of times per second, many times quicker than the green catch) switching on and off so only part of the AC power is delivered to the water heater. As such, it is much more accurate.
In terms of reliability, I can only state this. Switching on and off a 3600W element for example is not easy. The components involved are under stress regardless of the mode of operation. Like computer power supplies, they won’t last forever. So use the advertised warranty and life expectancy to make a choice.
I have an ongoing problem with the internal time clock becoming inaccurate. Presently using grid power to boost at 9am just as solar starts performing.
No luck with a fix from Catchpower yet.