Kevin:
Thank you for your input. I have come to respect your opinion greatly.
I am the guy that posted
this thread. I was looking specifically to use high wattage and high voltage grid panels with an mppt controller. With the boom in grid solar, the price on these panels is coming WAY down, so the price/watt is very good. I thought I was good with the standard 39.somethingorother inch width of these panels. However, after having a closer look, they will be too wide to physically fit, regardless of shading.
If even 2 or 3 solar cells get shaded, it reduces the panel's output to, essentially, nothing, and it does the same thing to any other panels that are wired in series with it. It's because of the way solar cells are wired.
True. However, as mentioned in the above-linked post, there may be dollars and cents advantages to using high-voltage low-cost grid panels -- even if some get shaded. If I use 72 cell high voltage panels, I don't have to put two in series. Shading will only affect that panel, not two. Therefore, I lose (at face value) 190 watts, not 320 like you would.
As to 'too much' solar for the batteries, if the total price is lower, does that really matter? If I 'waste' solar capacity, I am only wasting sunlight, which is free. IIUC, with a 'too big' array, I should actually gain on cloudy days in diffuse light.
I spent a very frustrating few hours this morning calling various solar companies around North America. I get the impression that few really understand well. They just repeat what they have been told (or have heard). It is such a new industry that there is little (that I have found, at least) that is independently verifiable. Instead, there are 'gurus' that have their particular beliefs. Sure is tough to make an informed decision.
The hangup for me now is shipping costs. NO ONE in Canada carries the smaller 5" cell grid panels, so I have to buy them Stateside. All I can get here are the 6" cell 39" panels. Northern Arizona Wind and Sun stocks the 5" x 72 cell panels at $162.50 each. Six of them (which I have more than enough room for) would run $1137.50 for an 1140 watt array.
I just checked the
cost of the Renology 100 watt panels, and they are $139 each. Assuming I would lose some of my 1100 watt grid array to shading some of the time, lets compare that to an 800 watt array of Renology panels. IIUC, putting two panels in series doubles the voltage, but does not change the total wattage (though the mppt controller will produce some current muliplication). I would need 16 of them to get 800 watts. 16 x $139 = $2112. That is about double the 72 cell panels I am looking at. Please correct me if my math is wrong.
Even if I went to 160 watt 6" cell 18 volt panels (similar to what you use), those are about 27" x 60" Not a long way off from the 5" cell high voltage 72 cell panels at 31 x 63". And those I don't have to put in series.
So, honestly, I dunno. I'm getting tired of chasing this. At $441.09 to ship 6 panels from Northern Arizona Wind and Sun to Calgary, plus duty and brokerage fees, I'm thinking that I may wait till next year and just go to Flagstaff and buy them direct.
However, that is several months away, so I am still open to being reasoned with.
Thanks.
Frank.