For starters let me start by saying that I am a 25 Yr old Cadd Technician and former Computer Repair Technician. I work for a Utility Power Engineering firm out of Augusta Maine. 2 or 3 months ago I agreed to help my parents Upgrade thier existing solar power system. Thier current system is only 10 75watt siemens solar panels and Trace Power Panel with a C40 charge controller and a DR3624 inverter (POS)
. I was planning on upgrading thier system to an Outback PS2 system with a GVFX3524 inverter.
Now here is the problem, My parents got ansy and found a deal on the internet. 14 215watt solar panels for a really great price, almost 1/2 off. They asked for an explanation and he said he works with a solar company out of Southern California and these were left over from a project with the Utility, he got a great deal and was going to mount them on the roof of his new house but then decided to sell the house and the panels were still sitting in storage in open, but original boxes. The guy also said he was comming to Maine for thanksgiving and could bring them up for us to check out. If we wanted them, we could buy them right there, if not we could tell him to take a hike. So they agreed. They met with him and the panels looked great, not a scratch on them. They bought the panels and brought them home. Then I looked at them, found out that they were SUNPOWER brand panels and when I researched them I found that they are supposed to only be used in a POSITIVE GROUND system. By my understanding, Due to this fact it seems that we cannot connect them to Outback MX60 controllers, unless we want to deal with up to a 30% loss in efficiency due to surface polarization. When I looked at the market for Positive ground inverters I find that in the USA only SunPower makes Positive Ground inverters that are designed for these panels. Sun Power only sells packaged systems with all the hardware (inverter especially) included. Im beginning to wonder were he may have got them as well, as this is sounding more and more like we got screwed.
-Anyway, they haven't decided what we are going to do yet. If we hook them up in the standard fashion it's my understanding that they will work, just that they could experience surface polarization which could reduce output up to 30%. I saw that thier smaller panels, SPR-90 are labeled "Do Not Wire In Series" but they are rated for battery charging and utilize the same back-contact construction method, this would seem to suggest that if you wire them all in parrallel that it would reduce or resolve the Polarity problem by keeping the voltage below 50 volts DC. Would I be right to assume this? If not what do you recommend they do about their situation. They don't have the money to buy new panels due to this, but they may have insurance against fraud so.... what should they do?