Solar PV with microinverters

thegentleway

Any other companies apart from Heatable that offer solar PV with microinverters?

charles_b_2

Microinverters seem like a good idea. I briefly considered them, but they do limit the watts as they generally work at around 380 watts max and most panels are now at 430-440w. Something to bear in mind.  I've gone with optimisers for my installation 

thegentleway

charles_b_2 said:

Microinverters seem like a good idea. I briefly considered them, but they do limit the watts as they generally work at around 380 watts max and most panels are now at 430-440w. Something to bear in mind.  I've gone with optimisers for my installation 

How often are your panels producing over 380W?

I thought clipping wasn't that much of a concern as it only occurs for a few hours on the brightest days. Add in a bit of dirt/shade/degradation and there's no more clipping?

charles_b_2

I'll find out next week when it's installed 

Screwdriva

thegentleway said:

How often are your panels producing over 380W?

I thought clipping wasn't that much of a concern as it only occurs for a few hours on the brightest days. Add in a bit of dirt/shade/degradation and there's no more clipping?

That's not entirely accurate. Yes, Enphase do make a micro inverter called the IQ8X, which allows for 380W peak generation. But this is not the model that Heatable defaults to, which I believe allows for ~360W if memory serves. Doesn't sound like a substantial difference, but with the latest generation of panels approaching 440W and 23+% efficiency, I'd argue that clipping may occur more than we may like during the peak generation months. 

thegentleway

Screwdriva said:

thegentleway said:

How often are your panels producing over 380W?

I thought clipping wasn't that much of a concern as it only occurs for a few hours on the brightest days. Add in a bit of dirt/shade/degradation and there's no more clipping?

That's not entirely accurate. Yes, Enphase do make a micro inverter called the IQ8X, which allows for 380W peak generation. But this is not the model that Heatable defaults to, which I believe allows for ~360W if memory serves. Doesn't sound like a substantial difference, but with the latest generation of panels approaching 440W and 23+% efficiency, I'd argue that clipping may occur more than we may like during the peak generation months. 

Heatable initially offered me Enphase IQ8MC at 325W then upgraded to IQ8AC at 360W when I mentioned clipping.

How often are your panels producing more than that?

Screwdriva

thegentleway said:

Heatable initially offered me Enphase IQ8MC at 325W then upgraded to IQ8AC at 360W when I mentioned clipping.

How often are your panels producing more than that?

I'm not surprised. Heatable used to offer the IQ7 till 4/24, which was limited at 280W if I'm not mistaken. Glad to see they're heading in the right direction - they really should be offering the IQ8X as default, especially as their panels are REA bifacials, a top tier panel capable of generating close to 500W.

I have 6 X 550W bifacial panels which have generated in excess of 600W on several occasions, so I'm afraid microinverters are not ideal my roof. 

thegentleway

Screwdriva said:

thegentleway said:

Heatable initially offered me Enphase IQ8MC at 325W then upgraded to IQ8AC at 360W when I mentioned clipping.

How often are your panels producing more than that?

I'm not surprised. Heatable used to offer the IQ7 till 4/24, which was limited at 280W if I'm not mistaken. Glad to see they're heading in the right direction - they really should be offering the IQ8X as default, especially as their panels are REA bifacials, a top tier panel capable of generating close to 500W.

I have 6 X 550W bifacial panels which have generated in excess of 600W on several occasions, so I'm afraid microinverters are not ideal my roof. 

The datasheet they sent me for the REA bifacials says 440W peak power?

What does on several occasions mean though? If it's a couple of hours on a couple of days a year then it's not worth worrying about. Hence the question: how often would a 440W panel produce more than a 380W microinverter can handle? As in how many hours a year.

Exiled_Tyke

Is this discussion limiting itself to Enpahse?  I did a small extension to my system adding two 300w panels which share a 500w micro inveter.  It does exactly what I need it to and probably is about right for efficiency versus clipping. 

Screwdriva

thegentleway said:

The datasheet they sent me for the REA bifacials says 440W peak power?

What does on several occasions mean though? If it's a couple of hours on a couple of days a year then it's not worth worrying about. Hence the question: how often would a 440W panel produce more than a 380W microinverter can handle? As in how many hours a year.

Bifacial panels can experience an uplift over and above the stated panel rating through what is called the albedo effect. There are several variables including 1) painting the area immediately behind the panels white 2) elevation 3) aspect 4) azimuth 5) weather conditions etc. 

Here's are a couple graphs which illustrate this:




In my experience, 5-10% gains are realistically achieved on rooftop installations. Here's a video showing Heatable's results, when they compared a standard panel to their REA bifacial panels within the same installation. 

charles_b_2

I took a quote from Heatable and it was all remote, noone visits until you accept the quote.  They also changed the battery make when I got the full quote documents. I would say be wary as they use independent contractors for the work ( much like Boxt).
I used a local firm in the end who worked with me (and I had great advice from @Screwdriva ) alongside 2 other quotes, all of which included a free onsite survey  with no obligation (including one from a reputable company that Screwdriva recommended).  There will likely be a world of different solutions and prices, and you need to do some serious research on the right option for you.  I'm going with Solaredge totally (optimisers, inverter, battery, gateway) with anti-islanding in case of power cuts. Micro inverters seem like a good idea, but if they fail you'll have to get back on the roof which adds potentially costs for re-scaffolding.