TradesHow this works
Enter your DC array size and your climate. The tool sizes the inverter for the three common DC:AC loading ratios, shows the clipping risk of each, and recommends one for your climate. A higher ratio uses a smaller, cheaper inverter and harvests more in weak light, and the cost is clipping the sunniest peaks.
Cool, clear sites make more DC power and clip sooner, so they lean to a lower ratio. Hot, high-sun sites tolerate a higher ratio with little clipping. Whatever the climate says, the inverter datasheet has the final word on the maximum DC input and ratio.
Common questions
What is a good DC to AC ratio for solar?
Most residential systems run between 1.10 and 1.30, with about 1.20 to 1.25 the common sweet spot. It means the DC array is 10 to 30 percent larger than the inverter AC rating. The best number depends on your climate and the inverter model.
Why is the array bigger than the inverter?
Panels rarely hit their nameplate rating in the real world because of heat, angle, and haze, so an inverter sized to the full DC would sit idle most of the day. Oversizing the array keeps the inverter near full output for more hours and captures more energy in mornings, evenings, and cloud.
What is inverter clipping?
Clipping is the peak DC power the inverter cannot convert on the sunniest days, so it caps the output at its rating. A modest amount, up to about 2 to 3 percent of annual production, is normal and designed in, because the extra DC earns more the rest of the year than it loses at the peaks.
Does climate change the ratio?
Yes. A cool, clear site runs cooler panels that make more DC power, so it clips sooner and should lean to a lower ratio. A hot, high-sun site runs panels hotter and rarely hits nameplate, so it tolerates a higher ratio with little clipping and more weak-light harvest.
Can I just use any ratio I want?
No. Every inverter has a hard maximum DC input and a maximum DC:AC ratio in its datasheet, and the string voltage and current must stay inside the inverter operating window. Those limits override the climate targets here, so check the specific inverter model before you commit.
Sources: Residential DC:AC (ILR) typically 1.10-1.30, ~1.25 common; up to 2-3% annual clipping accepted (Solargis, Aurora Solar, Solar Power World) · Cool/clear sites run higher DC and clip more (lean low); hot/high-sun sites justify a higher ratio. Engine version 1.0.0. Risk tier 2.