cracovian said:
I apologize for all this disconnected info but any comments on hardware, installation tips, pricing and sourcing would be greatly appreciated. Thanks again.
Thanks for providing the details on your system! It looks very nice.
I guess I have to wonder if you REALLY need to use the M250 for 280Wp-rated modules in GA. While it is true that Enphase only recommends the M215 for modules rated up to 270Wp, I'm willing to bet that for your particular installation, you could use the M215 and almost NEVER limit the output power due to the microinverter limitation. You could likely save about $30/inverter by making this one change on future upgrades (although if you installed even-higher-wattage PV modules, then the M250 would likely be desirable).
Let me provide a bit more information in support of this idea:
-
Since the beginning of August I have had both M190s and M215s mounted on my roof connected to identical 235Wp PV modules in virtually-identical conditions. Those are mounted on a nearly-south-facing 7/12-pitch roof at 39 degrees north latitude. The peak rating of the M190 (200W) is 85% of the PV rating while the peak rating of the M215 (225W) is 96%.
- Note that the peak power rating of the M250 matches its nameplate (250W), but the peak rating of the M215 is 10W higher than nameplate: 225W. (However, you typically pay for them per nameplate watt.) As a result, for your system, the peak rating of the M215 would be 80% of the PV rating while the peak rating of the M250 would be 89%.
- The difference in production for my M190s and M215s so far is zero. I won't know the year-round total differences until I get through about April, but I am surprised that with temperatures in the 20Fs, there is truly no difference in production so far in November. I expect small differences in January through March, but I doubt the year-round average will be over about 1%, if that.
- Your roof pitch is similar to mine, but you live in a climate that is 5% lower in latitude, so the sun is higher in the sky during all parts of the year, so the sun will be farther from the boresight of your array during the coldest months. Also, the temperature during those coldest months is quite a bit higher than here. As a result, conditions which cause the 85%-rated inverters in my system to limit will probably be more common than conditions which would cause 80%-rated inverters in your system to limit.
Bottom line: You could reduce the bill-of-materials cost for upgrades to your system by 7 to 10% while impacting production by less than about 0.5%.
If you purchase the materials and do the installation yourself, you will save the most money overall.