Choosing the right inverter size is one of the most misunderstood parts of designing a solar system. Many people assume the inverter should match the panel array's wattage exactly — but that's not how it works.
The Basic Rule: DC-to-AC Ratio
The general rule is to size your inverter slightly below your total panel wattage, typically within a DC-to-AC ratio of 1.1 to 1.3. For example, a 10kW solar array usually pairs best with an inverter rated around 7.7kW to 9kW.
This works because panels rarely produce their full rated output at the same time. Temperature, panel angle, and less-than-ideal sunlight all reduce real-world production below the spec-sheet number.
Why "Oversizing" the Panels Is Normal
This intentional oversizing of the panel array relative to the inverter is standard practice. It helps capture more energy during low-light periods mornings, evenings, and cloudy days without paying for inverter capacity that would sit unused during peak sun hours.
What Happens If You Get the Ratio Wrong
Undersized inverter: leads to "clipping," where excess DC power beyond the inverter's AC capacity is lost during peak production.
Oversized inverter: wastes money on capacity your system will rarely use.
A Different Case: Microinverters
If you're using microinverters instead of a string inverter, this math doesn't apply the same way each panel gets its own small inverter matched to that specific panel's wattage, rather than one central unit sizing the whole array.
The right size ultimately depends on your panel wattage, local climate, and inverter type. Rather than relying on a fixed ratio, it's worth calculating this for your specific setup.
Full breakdown here: https://solarbazaar.io/
