On 26th Nov my microinverter monitoring showed 45kWh generated. Woo Hoo!
Microinverters… In my experience, Aussie solar installers either love ’em or hate ’em. Seriously! I honestly don’t think I’ve talked to an installer that is indifferent to them.
The installers in the “I love microinverters” camp will rave about:
- Their performance. They claim they blow conventional inverter systems out of the park when it comes to power output.
- Their monitoring. They love the fact that the end user can know at any time if their system is performing optimally.
- Their ease of installation. They claim they are much easier to install.
The installer in the “I’ll chew off my right arm before I install one of those devices of satan!” camp usually cites these arguments:
- They claim they are unreliable. They get super hot on the roof in the sun and many installers claim they have seen huge failure rates.
- Their claim their performance is over rated
- They claim they are a customer service nightmare, because they can get a call every time the output on the monitoring system dips slightly
I personally think that the disadvantages of microinverters can be overcome by good engineering. It is completely possible to make a micro inverter that can withstand Aussie conditions for 25 years plus. Although I’m sure we’ll see many poor quality ones on the market first!
As for the customer service argument: good software can guide the customer and advise if a service call is really necessary.
As for the performance claims. The evidence I’ve seen so far shows that, averaged over a whole year, a microinverter system will produce about 8% more than a central inverter connected to identical panels. And that’s only going to improve as micro inverters get more efficient.
Anyway, I recently moved from Brighton Public Library to a custom designed, straw bale SQHQ, and thought I’d put my money where my mouth is. I bought a 6kW solar system powered by SolarBridge microinverters. My thought process was along the lines of:
“If microinverters are so unreliable, I’ll have loads of material for the blog as I bitch about them all year long!”
So far, after 3 months, they’ve not missed a beat. Hot Damn!
I do have to say that I am absolutely blown away by their performance. On a good day in November my 6kW system will produce 45kWh. That’s bloody good for a 6kW (15 deg pitch, directly North) system. PVOutput.org shows high performance systems in my area with central inverters produced about 38kWh on the same day, that’s 18% lower.
Obviously I need to run the system for a lot longer than 3 months to draw any meaningful conclusions. But so far, I’m super happy with my micro inverter system.
About Finn Peacock
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G’day.
Although I’m a fan of the KISS principle it’s hard to ignore an 18% increase in (presumably) efficiency.
One problem is that I’ve never even heard of microinverters.
Can you provide a succinct rundown on what ~ precisely ~ they are and how they work?
If (guessing) they’re attached to each panel, how does thatv effect the need for a regulator (‘controller’)? How seriously are the )exposed) heat-effects? Are they repairable or do they need to be entirely replaced?
That sort of thing.
Hi dabbles,
Everything you need to know about microinverters here:
http://www.solarquotes.com.au/inverters/micro/
Hope That Helps,
Finn
Thanks. Never too much information.
Finn, have you reviewed the Renesola Microinverter – i been trying to get a price for one here in australia ?
No – I’ve never seen one in the flesh. I’ll let you know when I get my hands on one – or when I’ve talked to an installer that has used one in anger.
Hello, can you please do the cost breakdown for these devices, how does it compare to a single inverter. Did you purchase the panels with integrated micro, or did you match them separately..
I can only find one supplier in Australia, which is significantly more expensive, and as the cost increases then then margin for the installer will be comprised.
I paid $15,000 for 6kW (yes – expensive!) about 10 months ago. They will be cheaper now. Expect a 20-30% premium for good micro inverters right now. My panels are Tindo Solar. Made in Adelaide and the inverter is factory fitted to the panel.
Finn,
I paid $1.85/Wp installed late November 2012 for a system with Enecsys MI here in QLD.
The reason I have chosen for MI was that I needed the modules to be installed on 3 different oriented roofs and because I had some shadow issues early morning and late afternoon.
I have been impressed with the results till now, especially when comparing our PV system with a few others in the neighborhood: http://pvoutput.org/comparem.jsp?sid=14516&sid1=21074,20811,13872,14517,1286&c=2
Very interesting. I’m working through the options for an off-grid system to add to my existing 10kW grid-connect installation so I can flog the entire output.of the big system.What I see as a major advantage of AC panels is the ability to incrementally add panels over time instead of having to guess how big an off-grid inverter I may need in a few years time. Can anyone advise whether or not there are any issues with AC panels and off-grid use ??
YM,
The only disadvantage is that you’ll need a extra inverter/PSU to step the panel voltage down from 240V to 24V to charge your batteries. So that will be a modest extra expense and you’ll lose 2-3% in the conversion.
Finn
OK, that makes sense. I gather the extra inverter required would only need to be of a size sufficient for battery charging during daylight hours however, the regular 240v output being used to run whatever other electrical loads. What would be wrong with simply plugging in a common or garden variety battery charger to the 240v output ?? Are there any particular ‘gotchas’ with energizing the microinverters considering they are (as far as I’m aware) intended for grid-connect use ??
The problem with a battery charger from SuperCheap Auto is
a) it is probably not designed to cope with a wildly fluctuating AC supply (e.g. when a cloud comes)
b) it is probably very inefficient
I don’t know of anyone with an off grid microinverter system!
Fair enough, I don’t need to be leading the pack so I’ll stick with tried and proven technology. I’m doing fine with the existing grid-connect system & an additional 2 – 3kw off-grid one will easily supply all local needs, I love sticking the boot into politicians, they do it to us every chance they get .. its not often one gets the chance to return the favour 🙂 Better battery technology would be nice, maybe that will be available when the first ones come due for replacement. For the peanut gallery, cost-effectiveness is only one of my criteria, spite is also a significant factor.
I was of the impression that micro inverters could not be used for an off grid system because if they don’t see the incoming mains power they shut down (as do all inverters). Is there a way to ‘fake’ the mains voltage to get the micro inverters to power up? Can you have a battery powered inverter making 240VAC that lets the MIs power up to make more 240VAC which in turn charges the batteries? Sounds somewhat incestuous.
The other downside of MIs in my opinion, is that they seem to all rely on sending performance data to a central web based database that allows the user to log on to view the data. I would prefer to keep it all in house and private.
Good point David – they may need a firmware change to operate properly in an off grid system. But it is technically feasible.
Hulloo-o-o-o. I’ve repeatedly asked for such ‘firmware’ (or anything else that will allow me to use my grid-connect inverter in a stand-alone situation.
If it IS “technically feasible”, I’ll be first in line with my chequebook in hand the minute some whizkid comes up with a way to defeat the ‘anti-islanding’ component.
Finn, do you know much about the Enphase system? I’ve been quoted $8300 for 17 suntech 250w panels with 17 of the 215w enphase micro inverters. Do you know if enphase are one of the best micro invirter companies? Are the 250w suntech poly panels good? And is this price a fair one?
I’ve no direct experience of Enphase – but they have a good rep as one of the better micro inverter brands out there. They have huge market share in the USA.
$8300 is fair for a good quality 4.25kW microinverter system. You would likely get a good DC system for less. Your call if it is worth more for micros.
I would also ask how confident they are that the 215W inverters won’t constrain the max output of the 250W panels.
Suntech are good quality panels although the company ownership was very up in the air last time I checked.