What about somewhere like southern Maine? I'm sizing microinverters for a given panel type. Is 125% panel/inverter really the optimal?
I'm just looking at the panels you have on special, the Thaisun ones. They're 320w, which I would have thought would need an S280 inverter, but it looks like the S250 might be closer to the 125% number.
Take it you need to take into account the peak energy
of the area as well, since we only get max sunlight for like 4 hours.
There is always a discussion to be had on the topic. It really depends on your goals.
If it is a price
conversation and with the higher wattage modules, there will be some
overdriving. Both should
work for you. But to be sure
check out Enphase Compatibility Calculator
You might really want to avoid clipping. However also consider the exposure in your area, maybe you do not actually reach the full panel production anyway. The ratings are given based on ideal laboratory settings. Some site like NREL’s PV Watt( http://pvwatts.nrel.gov) is very helpful to get an idea of how much production you can actually get in your area. Solar Radiation ( kWh / m2 / day ) is the general term used for solar exposure. Modules are tested, and rated, at 1000 W/m^2; this is instantaneous power. For more on how to get to kWh’s or system power read our training item: http://www.renvu.com/Bigger-Is-Better-Big-Solar-Modules-For-Small-Microinverter , or for derating and system load information http://www.renvu.com/What-Solar-System-Size-Do-You-Need.
These will lead you to needed larger or small panels depending on were you live. Because you are in Maine, modules perform better in Cold weather. The temperature coefficient can be used to show how much Higher voltage ( and hence more Watts) your module will produce than the name plate rating. Following that you will want a micro-inverter that can accept the higher voltage.
Our Solar Kit Guide does this automatically for you. When you adjust your minimum temperature on the inverter selection page. Our kit will also show you the overdrive rate, for the possible options. Keep in mind also, the unfortunate truth, due to the degradation of the modules, the overdrive will reduce over the life of the modules.
Also keep in mind the inverters are rated as AC power out. Compared to the rated DC power output of the modules. More to come on this point!