I don't know, exactly, but I nearly always have enough conductor ampacity headroom that it wouldn't make any difference to the design.Would you use the bifacial gain current Isc or the rated Isc? I see most of the time they use the normal Isc value but I have never been able to confirm with someone who specializes in solar design.
I don't know, exactly, but I nearly always have enough conductor ampacity headroom that it wouldn't make any difference to the design.
My read is that marketing is boosted with higher efficiency ratings, and vertical orientations that avoid snow load. Nameplate values still determine conductor size, fuses, & inverters.Like is it just a small bonus or is it something that can play an impact on design parameters.
Yes, but the data sheets for many bifacial modules show different nameplate values for front side only and front side + back side illumination. Voc does not change but Isc does.My read is that marketing is boosted with higher efficiency ratings, and vertical orientations that avoid snow load. Nameplate values still determine conductor size, fuses, & inverters.
Seems like NEC 690.8(A)(1)(a) gives us 2 options:Yes, but the data sheets for many bifacial modules show different nameplate values for front side only and front side + back side illumination. Voc does not change but Isc does.
That's just the binning that they do after production. If you buy a 475W panel, you might get one that tests out anywhere from 475W-479.9W (as per the data sheet spec of +5W, -0W). So if you want to be conservative, you should use the data sheet Isc values for a 480W panel, as those will also be maximum Isc values for the 475W panel.They also call it minimum at test conditions which also throws me off.
The Isc shown for BSTC column appears near 10% of adjacent column, perhaps not overkill If it includes both sides.BSTC is what they call the bifacial values.
Me too. Also reference IEC standards —perhaps not harmonized with NFPA-70 maximums needed for Article 690.They also call it minimum at test conditions which also throws me off.
That's just the binning that they do after production. If you buy a 475W panel, you might get one that tests out anywhere from 475W-479.9W. So if you want to be conservative, you should use the data sheet Isc values for a 480W panel, as those will also be maximum Isc values for the 475W panel.
Cheers, Wayne
That CSA logo is an OSHA certified NRTL, which confirms compliance with applicable American National Standards.
They also call it minimum at test conditions which also throws me off.
Good question, although the point of my earlier post was that this "minimum" issue is a separate one.Would you use the bifacial Isc or the nominal one?
The Isc shown for BSTC column appears near 10% of adjacent column, perhaps not overkill If it includes both sides.
Me too. Also reference IEC standards —perhaps not harmonized with NFPA-70 maximums needed for Article 690.
Good question, although the point of my earlier post was that this "minimum" issue is a separate one.
I guess it would depend on the details of the installation. If there was zero chance of backside illumination, I'd use the STC figures. Otherwise, I'd investigate what "at BSTC: 1000 W/m² + φ × 135 W/m², φ = 70 % ± 5 %, 25 ± 2 °C, AM 1.5 according to IEC 60904-3" means and whether it adequately covers the possible backside illumination for the installed configuration. If it does, then the BSTC Isc would be the ticket.
Cheers, Wayne
Per the datasheet in post #9, it does change, but only by 0.19V per panel, or about 0.4%. So unlikely to be an issue, unless the string Voc based on STC without backside illumination was extremely close to your limit.Of course, the most pressing issue would be the voltage, which when I (prematurely) posted my question I did not snap to the fact that it would not change (duh again) if the back side of the module were illuminated.
I did not look at that one, but the ones I did look at did not show a change. It's not an issue for me because I would not design to within 0.4% of the maximum allowable string voltage, anyway.Per the datasheet in post #9, it does change, but only by 0.19V per panel, or about 0.4%. So unlikely to be an issue, unless the string Voc based on STC without backside illumination was extremely close to your limit.
Cheers, Wayne
That appears to match power class 485. The corresponding BSTC column is 530.5In this instance they installed 1,628 of them and said the size was 789.58kW DC.
