I have one Enphase customer with a ground mount with Sharp 224s and Enphase 190s. The inverters can stay pegged for 4 hours at a time in the spring.
Emacs!The graph above was from a day with some clouds, but still power limited much of the day.
It would be good to get a better understanding of the annual percentage effect. Enphase claims an overall power increase, even with this effect. Undersized string inverters are clearly an issue.
Drake At 12:37 AM 3/22/2013, you wrote:
Thanks for sharing the screen capture, Marco.Interesting issues to think about here. This is actually prime clipping season in many places (not sure about Hawaii) due to the cool weather. While there are more sun-hours in the summer, the cell temperatures are often high enough that you won't tend to see rated power out of the modules.While I'm not running performance models for work, the people who do are routinely increasing dc-to-ac ratios, often as high as 1.4-to-1. Having said that, most inverters aren't installed on a roof. (Not yet anyway.)I'd probably lean to a more conservative sizing ratio for micros. While I can imagine some scenarios where I'd be comfortable with a 215 W micro on a 265 W modulelike a flat roof install in Vermont, which reportedly doesn't see 1,000 W/m^2 very oftenI wouldn't try that here in Texas.On Mar 21, 2013, at 7:54 PM, Marco Mangelsdorf wrote:Check out the output of the modules below at 1PM on this Spring equinox for this system here in Hilo, Hawaii.These mods are SunPower 245s with the Power-One micro 250s. Notice that the AC outputs below are 223 watts and higher.If we had installed Enphase M215s instead, the max output possible would be ~ 224 watts.If theres clipping this early in the year, imagine the degree to which the clipping will be increasing in the months to come as the solar insolation increases.And these mods were only 245s. Enphase states that their M215s are fine with modules up to 265 watts! Imagine the amount of clipping taking place when that kind of pairing takes place.marco <image005.png> <image006.png> _______________________________________________ List sponsored by Home Power magazineList Address: <mailto:RE-wrenches@lists.re-wrenches.org>RE-wrenches@lists.re-wrenches.orgChange email address & settings: <http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org>http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.orgList-Archive: <http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org>http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.orgList rules & etiquette: <http://www.re-wrenches.org/etiquette.htm>www.re-wrenches.org/etiquette.htm Check out participant bios: <http://www.members.re-wrenches.org>www.members.re-wrenches.org_______________________________________________ List sponsored by Home Power magazine List Address: RE-wrenches@lists.re-wrenches.org Change email address & settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.orgList-Archive: http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.orgList rules & etiquette: www.re-wrenches.org/etiquette.htm Check out participant bios: www.members.re-wrenches.org
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