It sounds wrong at first: why would you deliberately connect more panels than your inverter can handle? But nearly every modern grid-tied system does exactly that. The trick is the DC/AC ratio — the array's DC capacity divided by the inverter's AC rating — and getting it right saves money without throwing away meaningful energy.
Why oversizing the array makes sense
A panel's nameplate wattage is measured under perfect lab conditions. In the real world, heat, dust, wiring losses, imperfect angles, and hazy skies mean your array almost never delivers its full rated output. So an inverter sized to match the array's nameplate would spend most of its life running well below capacity. By making the array a bit bigger than the inverter — a DC/AC ratio above 1 — you keep the inverter working in its efficient range for more of the day and harvest more total energy per dollar of inverter.
What clipping is
The catch is clipping. On the sunniest moments of the best days, the array can briefly produce more power than the inverter can pass through, so the inverter caps its output and the surplus is lost. This only happens at the peaks — a few hours around midday on clear days — so the annual energy lost is usually small. A little clipping is expected and fine; it's the price of a right-sized inverter.
The sweet spot
For most systems a DC/AC ratio of about 1.1 to 1.3 is the sweet spot. Below 1.1, you're paying for inverter capacity you'll rarely use. Above 1.3–1.4, clipping losses start to add up — faster in sunny climates, where peak-irradiance days are common, than in cloudy ones. Because peak sun hours and climate drive how often you hit those peaks, the ideal ratio is a little higher for cloudy regions and a little lower for very sunny ones.
Related tools
To size the inverter from your actual loads, use the inverter calculator. To estimate how much energy the whole system will make, try the energy production calculator, and to size the array itself, the panel calculator. For string layout within the array, see the string sizing calculator.
Frequently asked questions
What is a good DC to AC ratio for solar?
About 1.1–1.3 for most grid-tied systems. Below 1.1 wastes inverter capacity; much above 1.3–1.4 loses energy to clipping, especially in sunny climates.
What is inverter clipping?
When the array briefly makes more DC power than the inverter's AC rating can pass, the inverter caps output and the excess is lost. It only happens at midday peaks on the best days, so the annual loss is usually small.
Why do installers oversize the array relative to the inverter?
Because panels rarely reach nameplate output, an inverter matched to the full array rating would sit idle most of the time. A ratio above 1 keeps it efficient for more of the day and yields more energy per dollar of inverter.