New inverters compatible with old Sunpower positively grounded panels?
ToddF Registered Users Posts: 6 ✭✭
I have a 12 year old system with over 200 Sunpower SPR-305-WHT-U modules which are positively grounded. The old transformer based inverters were set up for positive grounding. All ten inverter are defunct and as far as I can find nobody makes a transformer based inverter anymore. Anybody seen this issue and have a solution? There are thousands of these panels installed worldwide. PS Sunpower had no solutions.
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Fronius USA is located in northern Indiana....give them a call...a good group of people.
Thanks for responding. I'm not clear on the concept but those modules had both + and - terminals on the back side of the cells which I believe made a positive charge build up on the top side of the cell. That worked contrary to voltage flow thus decreasing it. I believe the positive grounding swept off the positive charge so full voltage flowed. I was under the impression that the problem made a big dent in the total output power. It is a 12 year old system with expected degradation so a 3-5% hit would be nada. Can you please explain why you believe the loss is so minimal??? I would love to be able to just buy new transformerless inverters and plug them in. Thank you!!!
The current crop of non-isolated inverters will work just fine with your old panels, I'm currently using a pair of Solis 5G's, you may want to look at the 4G line, best bang for the buck on the market and rock solid performance.
Search for Solis-1P10K-4G-US-SPRT online. You should be able to easily replace the 10 inverters with 6 of these ( or less ), they have 4 mppt channels in a 10kw box that is convection cooled, no fans needed.
If this installation is 3-phase, Solis has larger units starting at 75kw that might be a better fit. https://www.ginlong.com/us/inverter.html.
It is a 3-phase system but it is using a mix of ten 8k and 6.5k Fronius and four 5k SMAs, all single phase inverters balanced on each leg. I wouldn't do that again because one bad inverter can throw off the whole system. I think I may pull the old SMAs and go with 3 phase all around.
Solis is the largest string inverter company out of China and been around for close to 20 years, there are US retailers that carry them, I use one from Texas for the 5'g's I own.
With a single 75K unit you could replace everything for half the price of 10 inverters, but I'm not trying to promote a brand, just the options I'm familiar with. With code requiring RSS and / or optimsers or shutdown per panels for new system, not many options for string inverters these days.
They, the Sunpower (+ ground) panels really are old now BTW.
Many people are wanting a battery based system these days and you would have to make sure it is legal for insurance if you carry it. One way around that is to ground mount the array. You need to check on this for your area and situation!
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