zanydroid
Solar Wizard
America be weird like that.
Residental Solar 12.8 kw system outputting 9.96 kw
- Thread starter keymaster
- Start date
Mike 134
Solar Enthusiast
He has a solar edge system with optimizers . Low limit on a string is 8 panels, high side is 20-22 forget the exact number. Those inverters have 2 string inputs that would not be obvious without opening the inverter.
zanydroid
Solar Wizard
I think the overpanel calculus is a little different with solar edge. You already pay a lot per panel for those optimizers, so adding a bigger inverter probably incrementally costs a little less than with a regular string inverter.
Ampster
Renewable Energy Hobbyist
There are a lot of reasons for DC to AC ratios above 1 to 1 but that is not the issue in this case where the OP was given a specifric set of equipment. Unless the original solar contractor gave him a performance guarantee and said that the equipment was representative of what would generate those numbers. Then a case could be made using PVWatts that the system he got might be close. However with 12.8 kW in panels and 15.2 kW in inverter that is a DC to AC ratio of less than 1 to 1 I think the performance will be somewhat less and the OP loses the andvantage of two inverters on two separate strings which gives him some redundancy. While I generally favor ratios in the area of 1.3 to 1, in this case the OP has a good case to argue for the specific inverter and string combination for which he contracted.
Ampster
Renewable Energy Hobbyist
That is the big unknown in this case and that needs to be understood if that was the reason for the change. However the original contract was for two 7.6 kW inverters totaling 15.2 kW so if the original contractor made that mistake can he reasonably argue that it was beyond his control. That is a factual issue that needs to be understood before pressing for specific performance by forcing the contractor to replace the 10 kW inverter with two 7.6 kW inverters.
Ampster
Renewable Energy Hobbyist
He contracted for 32 panels so two strings 16 each sounds like an optimum configuration. That is another good point if he truly has 32 panels on a single string. That is a fact the OP needs to confirm.
wattmatters
Solar Wizard
Yes, thanks, that was pointed out to me a little earlier and makes sense now. I should have tweaked earlier when I saw the inverter model.
Solaredge is kind of a weird hybrid between string inverter and optimiser set up. And they tend to lock you into their platform with anything else you might want to do later on.
In any case it should still be 2 strings of 16 panels, not 1 of 32 panels.
Solaredge are only marginally popular down under. US has its own unique PV isolation rules which mean optimiser and micro inverter systems are more common that straight out string inverters. Maybe that's one reason why grid-tied PV is a lot more expensive over there than here.
The OP is going to need to review their sales contract but a remedy of some kind sounds like it should be provided. If my energy budget resulted in wanting that specific larger system, then that's the remedy I would be seeking.
wattmatters
Solar Wizard
Either way, such a change should have involved customer consultation as it may result in a different option being considered/chosen.
Ampster
Renewable Energy Hobbyist
No question about that. I presume we are both commenting from the same perspective of English Common Law when it comes to contracts.
wattmatters
Solar Wizard
Contract or not, it's just the right thing to do.
Assuming the story we are being told can be taken at face value then this installer's behaviour is on the wrong end of the commercial cultural spectrum ranging from doing what's right for your customers to doing whatever you can get away with.
I wanted to get your opinion on the 1 string. In the solar edge app this what I see. A single string of panels connected to the inverter. That is the basis of my one string comments. I guess this could be something in the app? Not brave enough to actually crack it open and start counting wires.
wattmatters
Solar Wizard
For sure that set up looks weird. Since it's Solaredge I'm going to refrain from comment as I am less familiar with their general string structure.
Agree that you need to supervise if not doing it DIY. But are there any solar installers around that have been doing it for 30 years?
I hope this all works out OK as it sounds that you have clear documentation as to what you were promised. But am a little puzzled why you paid in full when they turned the system on... wasn't it clear at that point there was only one inverter, rather than two?
zanydroid
Solar Wizard
There is at least one around me that has been around since the mid 1990s and made it to milestone of installing two systems on the same house after the first one hit 25 years/obsolescence….
They are supposed to be rock solid, but they also cost like $4.5-5/W vs $3-3.5/W