So you’ve just enjoyed your first solar summer with a basic 6.6kW system, but you’re finding the bills in winter still give you the chills, don’t worry; you’re not alone. It’s not uncommon for new solar installations to undergo expansion after the first winter. Read on as I explain how.
This article looks at buyer’s remorse for new systems that should have been bigger from the outset. If you have an older system, please check previous posts in my ‘How to upgrade’ series:
“I’ve never had a customer complain they installed too much solar”
– Anthony Bennett
For years, I’ve used this as a succinct little catchphrase to encourage people to buy more solar panels. Some say it’ll be carved on my headstone, but recently I’ve had to defend this position. The internet experts are pushing back…
- Well, you would say that wouldn’t you, you’re trying to sell something
- It must be a con by big climate… see I told you there’s a SUN TAX coming now!
- People are just try to justify overspending to themselves, it’s ak!chully a waste of resources.
So I’m going to have to simplify it for both the slow crowd and the clever clogs. Remember that “excess” solar is a feature, not a bug.
For over 15 years, I’ve heard one consistent complaint from solar owners:
“I wish I’d installed more panels.”
This isn’t a sales spiel—it’s a common lament I’ve heard time and time again.
Summer on the left shows a mountain of solar, while winter on the right is disappointing when you realise the scale of the graph
An Example: Geez-I-Should’ve-Bought-More
Can my Fronius 5KW Gen24 3-phase – 6.6KWp system can have additional panels fitted?
My system suffers drastically with seasonal shading from council trees. Summer is fabulous, but with an additional bank of five north facing panels, I’d still get 2-3KW more output in winter. I had read the 133% rule can be skirted with a battery, but just to clarify, even then would I still be limited to just two extra panels? Perhaps I should price a small separate system, purely west facing.
Bin The 133% Limit With A Battery
As we’ve explained before, an archaic Australian rule limits solar installations, but installing a solar battery allows you to claim STC credits on the full rated capacity of an inverter. Some inverters can handle 200% or more.
Fronius are conservative so the 5kW Gen24 will handle 150% overdrive, or 7.5kW. At only 6 or 12 months old, finding two matching panels for your existing array is usually feasible.
However, you’ll still need to get the string configuration correct. Happily, Fronius have excellent current ratings, which allow flexible designs of parallel panels to get voltage down & group orientation correct.
Ring up your installer and get them back so that your warranty is kept intact.
In October, this system doubled in size so blue yield went up & grid consumption fell. Black circles still show winter demand is high though.
Can’t Add A Battery? Get A Whole Second System
If your existing solar is working well, there’s space on the roof and you can get a connection approval, then adding solar via a second inverter and solar panel array is often possible. Consider a hybrid inverter for your second system, so your next upgrade can be a battery.
Got 3 Phase? Get A Second & Third System
Network rules dictate how much of any load you can connect to the grid, and often they involve balancing things equally across phases. If you already have a 5kW single phase inverter, adding a 10kW single phase might not be acceptable, but two more 5kW units will.
Our cover image shows a 3 x 5kW system where the owner added a hybrid inverter and kept one of his GE units for a spare.
Whatever you choose, try to stick to the same brand so that you have one consumption meter, one management system, one app to watch, and, importantly, one warranty.
The Takeaway: Go Big AND Go Home
If you’re considering solar, think big. Starting small might seem safer, but the long-term benefits of a larger system are undeniable and upgrading is always harder & more expensive than going big from the outset.
More panels mean more savings, better future-proofing, and a greater positive impact on the environment. So, when it comes to solar, don’t hold back—you’ll thank yourself later.
About Anthony Bennett
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I wish I had of gone bigger and I’ve got 10.66 kw solar optimised with a 5kw solaredge hybrid inverter and a 10kw solaredge battery.
Cost is the biggest factor why I didn’t.
Can add another battery to the existing system but again at $11800 installed, cost is prohibitive
Or drop another $27k for the same system again on the second phase
I would suggest that in many cases, buyers remorse comes about by unscrupulous sales people and or practices.
For example, when I bought my 15 kw 3 phase system, I specifically stated at the time that within 12-18 months I intended to buy batteries and didn’t want to have to spend lots of money changing inverters or such. (Apart from the battery cost and installation of course)
I was sold 3 x 5kw grid tie inverters, a bit like the picture.
The bonus was that the electricity supplier was going to pay me 14 cent FIT, uncapped. Stupidly I believed them.
For the uninitiated the solar supplier has no control over your FIT.
So when the time came, it was a giant headache. Apparently what I wanted done was nearly impossible. (Batteries charging when the sun shone regardless of the grid being up or down, and power to all 3 phases when the grid was down)
They wanted me to replace all 3 inverters with hybrids. I reminded them of our conversation we had 18 months earlier to no avail.
So I ditched the supplier of the panels and ditched 2 of the 3, 5kw inverters and bought a Fronius Gen 24 3 phase Hybrid inverter and 33kw of BYD batteries from a different company that was genuinely interested in discussing MY needs rather than what they wanted to sell me.
Interestingly though, throughout this unpleasant business, I obtained 10 quotes from 10 different suppliers and they all gave me a slightly different version of the same BS.
For clarity my final solution came in 5k over the most expensive of the 10 quotes.
So, did I have buyers remorse? Yep.
So good people, when people tell you to do your research, you may think jumping on FB is the answer, well it ain’t. Use Google and when you find a company you feel might be ok, ask them for reference sites and ring the references. I did it in the end and made my decision on that basis.
You are going to spend your hard earned cash, do so armed with other peoples real experiences and you probably won’t suffer from buyers remorse.
I would love to put extra panels on my roof, but everyone I ask tries to sell me a complete new system which I don’t want because I replaced my 5KW inverter only two years ago!
I’m wondering how I can go about doing this when I already have 13.2kW of panels and a 10kW Sungrow SG10RS inverter on single phase. Swap the inverter for the SH10RS and also get a battery? System was only installed in December 2023 so would seem to be a huge waste of an inverter. Or maybe roll the dice and ask for DNSP approval for extra inverter capacity? Then might be able to get a hybrid system installed.
Like you, we already have what you have, and our current bill is $375 for the month, with 8 days to go. Our monthly repayments for the system are $361.
At around $800 per month, that still is lower than the $1000-1200 we were spending before the fit-out.
There’s gotta be a limit somewhere with “too much is just enough”, but with 65 panels and 27 kW, I haven’t found it. That’s just yielding around 3 kW in horizon-to-horizon grey overcast. And global heating seems to be increasing the incidence of that. Fortunately that ~10% yield is enough, though, to top up the battery from overnight off-grid drain, and supply a careful day’s loads. I.e. the large array obviates the need for a huge battery, making for a cheaper overall system.
Then, after a day or two of cloud soup, I can whack 38 kWh into the EV & HWS in a morning, and I’m well ahead again.
If there had been room for more panels on the roof, they’d have gone up. Wouldn’t need much battery capacity then. (OK, lotsa panels means more/larger inverters or MPPTs, but redundancy is a quality of its own when off-grid.)
A second EV soon justifies all the panels you can fit, I figure. There are such households already. Let’s look again in 2030.
I think rainy day/ winter’s day performance will soon be the new criterion for system performance.
When feed-in tariffs were 66c/kWh, panels were put at latitude angle, but these days, running out of roof space, we are starting to realise that flat roofs with horizontal panels maximise whole of sky radiation with 100% cloud cover and north facing vertical walls and fences offer close to optimum mid-winter power at Sydney latitude and south.
Now that’s an idea, Bill – fill not just the roof, but the north wall too.
I did build a 25m long north facing 40-degree tilted roof into the extension. Here at nearly 40 degrees south, that gives:
Equinox: cos(37.93 – 40) = 99.9% optimal
Winter solstice: cos(37.93 – 40 + 23.44) = 93% optimal
The north wall’s 90 degree tilt would then be:
Equinox: cos(37.93 – 90) = 61% optimal
Winter solstice: cos(37.93 – 90 + 23.44) = 88% optimal
As it’s in June – July that total array yield hits a nadir, finding extra roof on the walls, at 88% efficiency, is not shabby at all. (And a significant revelation.) Add that I’d only have to go through the wall to wire to the MPPTs or inverters, and greater convenience would be hard to find. The incidental sun shielding wouldn’t add a lot, as the wall is insulated. (But I did note today that inside the garage, a closed north facing light coloured roller door radiated enough IR heat to be felt on the skin at several meters.)
My experience is that rain massacres PV yield, whether because it’s thicker/denser clouds which precipitate, or due to the changed cloud composition. When it rains, I figure it’s time to minimise consumption, to conserve battery SoC, in case it lasts for days. (Cruising through winter without starting the generator would confirm the adequacy of my system design.)
Some retired folk take up gardening, but a solar installation is more fun than a train set, I figure. (Though I did bring home a 50m roll of netting yesterday, to keep the kangaroos off my cabbages. That should work better than having to open the bedroom window in the middle of the night to berate them. They don’t necessarily move unless you shine a bright light at them. (The kangaroos, not the cabbages.))
Am in Melbourne, and have got 6.4kW of panels installed (3 east, 1 north, and 14 west). Given smallish house, shading and roof suitability this is all I could fit but in an ideal world I’d love to bump up the number of north facing ones.
Using the Enphase panel level monitoring I can see that the single north facing panel has generated 18kWh in June versus an average of 12kWh for my west facing panels and 10kWh for the east facing ones.
West is great for summer, but north is best for winter & heating..
Looking at bigger Solar and battery’s for my house every scenario calculator I look at, and presumably real world as well, has battery’s being charged as soon as the solar systems start producing power in the morning with the assumption that the Battery is empty from the night before.
Most Battery’s under charge seem to consume everything produced by the Solar and as a result export to the grid only seems to happen when the Battery has had as much as it can take.
Such an approach when looked at through the micro lens makes sense, get the free power while its available and if happens that you get all that you need then provide export to the grid.
When you look at that scenario through the big picture lens then as Battery’s become widespread then solar grid export which is good when its controllable, will dissapear in much of the grid until lunch time and then it’ll be back as it always was as a problem because its too much…
Surely with the connectivity and intelligence available to us today we could get a better distributed charging scenario so that solar export will continue to be available while ever the sun is up, and charging should be staggered across all battery owners so that instead of the Battery becoming another source of Grid control issues we use charge of it as a means of stabilising the grid?
Thoughts?
You can (depending upon your battery) configure the maximum charge rate.
I have a BYD battery connected to my Fronius Gen24, and in summer I limit the charge rate to 150W until noon: my twin inverters are limited to 5kW export, so it exports up to that, and when it reaches >5kW it puts the rest into the battery. On sunny days this works, and my battery fills sometime in the early afternoon.
During winter, I’ve gone to an 8c/kWh 10:00-16:00 plan, and have programmed (using HomeAssistant and Modbus) my system to look at the current battery charge, and set the charging rate so it fills at 4pm. It won’t start discharging until 5pm when the peak rate starts.
At 9pm the peak period ends, and my automations then work out how much charge I’ll need for the morning peak, and the battery will charge back up to this amount.
I’ll probably revisit my daytime stuff (which was just using the in-built Fronius battery rules) to be even more clever, as there were a few days over summer where I didn’t fully charge the battery but could have.
Very clever Matt,
I’ve always liked the Fronius attitude to open access with modbus.
Do you have a good resource for others to start with if they want to explore Home Assistant?
I tend to agree Andy. I’ve recently added 15kw (Enphase 5P x 3) to my 32 panel Enphase IQ7a’s and have become frustrated with the lack of control of the solar charging. In an Ausnet region (Eastern Melbourne) with TOU solar grid resale, 10am-2pm is now worth only 2.1 cents per Kw. I’d prefer to hold charging until then but can’t (the order is house usage, battery until full & then grid). In the current winter scenario I’m using the top up from grid function @ 2pm to make sure the batteries are 100% full for the Peak TOU grid draw period (3pm – 9pm), but other than that the Enlighten App allows only manual intervention. I’ve seen similar requests on Enphase forums, but nothing offered yet. Is there another way, no idea, maybe I’ve missed something? It doesn;t strike me as rocket science to offer more flexibility….
Hi Jon,
Have you pushed Enphase support about it?
I know they are a bit insular and won’t offer APIs for third party integration with Catchpower for instance.
However the squeaky wheels get the oil…
Most of the information seems to assume string style inverters. I’m not sure how this applies to my system with Enphase micro inverters. Would it be easy to increase the size of my system in my case?
Hi Glenn,
We’ll have a whole article on micros soon, and probably one dedicated to Enphase
It really depends on how old your existing system is?
I decided to add a 6.72kW system including a 10kW Enphase battery to my existing Tindo 3kW Enphase system.
I thought the installation would be straight forward as all the current panels have Enphase IQ7 microinverters and the new panels would use the IQ8 microinverters, which are compatible.
However, during installation I was told that the original panels had the older microinverters rather than the IQ7 (which I was quoted for and paid).
This only meant that I would have 2 Enphase accounts.
However, I was then told during installation that the new REC solar panels could not use the IQ8 inverters and I had to use the lower powered IQ7 inverters. Had I known earlier during the design phase, I could have made changes to the microinverters or panels. Thus my new 6.72kW system has now been reduced to a 5.04kW system.
While the installer was excellent and his workmanship very professional, the sales team seem to have limited knowledge of these issues.
My biggest issue is that sales personal should not be saying they are selling a system based on simply adding all the max power output of each panel rather than being honest and actually giving the actual max power output taking into account microinverters or inverters limitations. I really think these sales tactics should be illegal.
Hi John,
Sadly I think you’ve found out that Enphase can be an acquired taste, and sometimes it’s bitter when the sales & design task hasn’t been adequately thought through.
Enphase can be brilliant, but they’re also fundamentally fussy insomuch that the panels have to be well matched to get the full 133% overdrive allowed under Australian STC incentives.
Best advice from here is the watch the monitoring like a hawk & compare the promised monthly yield on the quote to the actual results on your roof.
I’ve known a retailer who sold IQ7 series (rated at 10.2a input) with 13.5a panels.
It worked vut Enphase admitted it was a “disappointing” design & that effectively cost the customer 3 or 4% yield.
The retailer had to bolster the system with an extra panel for free to meet the shortfall.
Thanks for your reply.
I will certainly monitor the system.
I am still amazed how good my 7 year old Tindo panels are performing.
My biggest beef is companies selling large systems based on just adding the power output of the panels rather than taking into account inverter and micro inverter limitations.
I have taken this up with NSW Fair Trading to see what they say.
Generally I agree that bigger is better with solar, but consider your individual situation. I followed the advice from virtually everyone to “go big, you won’t regret it” and spent an extra $5000 or so to get a 9.5 kw system instead of a 5.5 kw one. However, I’m in a conjoined house with limited roof space, and the only place for those extra panels was on the south-facing roof. In summer, we generate way more power than we can use, but get almost nothing for it because we quickly hit our export limit to the grid. In winter, when we could use the extra power, those south-facing panels get no direct sunlight, so don’t really help us out at all. The only thing going for them is that they extend our generation slightly later into the evening in the summer months, since we have no west-facing roof to use.
As the disclaimers always say “consider if general advice is right for you…”
Thanks Emily,
It may be hard to quantify but my personal experience with 10.85kw (of which the panels are split 11 South and 24 North) is that the southern array really does help.
When it’s overcast & the system is only running at 10% capacity, we’ve still got an extra ⅓ yield basically.
And you’re right about peak summer, there are hours at the extreme ends of the sunny day where those 11 south panels are outright better performers than the whole 24 north array. This has an outsize effect when TOU rates mean imported power is triple the midday rate.
I’m interested to know how the south-facing panels are out-performing the northern ones. Are they oriented partially toward the west, or do you have some environmental shading or something that makes the difference? Or is the shorter string more efficient, or has a lower voltage drop on the runs back to the inverter, perhaps?
Hi Ash,
High noon & high summer in Adelaide 5° south orientation is actually best, so at the ends of the day the south array simply has better insolation.
The roof is in the title image here ;
https://www.solarquotes.com.au/blog/roof-orientation-solar-australia/
Ha! Fascinating. I didn’t realise the tilt was that much during summer that it would make a substantial difference.
Hi Ash,
It’s not at all intuitive but fascinating huh.
Mid winter this site suffers shade on the north array… again the south panels outperform.
Ive got a 24kw enphase system and with a few tall trees I averaged 30kwh production a day duringJune. But it only cranks that out between 10 and 2. So im importing another 30Kw for aircon in the morning and evening. I make sure I use most of the produced power on hot water units, appliances and pool pumps and any available excess on the afternoon shoulder is used to run aircon whether I need it or not to preheat the house for night. A battery would be useless as I need to import around 30KWH to run the aircon heat demand alone. And with a feed in tarrif of 5c I make sure I use every bit of solar goes into the house instead of the grid. So a 24kw system provides more than enough power for most of our needs but nothing would help us power our winter heating requirement of 30KWh a day. A battery would be useless with that load. Even though the house is designed to meet 10 year old NSW basix requirements it fails miserably to capture and retain heat