How Much Should My Solar Panels Produce?

Enter your system size and location to see how much electricity your solar panels should generate each month. Then compare it to your actual production to see if something is wrong.

By Rich, SolarDoctor founder · 20 years in solar energy

Average US home: 6-10 kW

Panels degrade ~0.5%/year

11,426

kWh per year

952

kWh avg per month

$1,828

annual savings (est.)

Expected Monthly Production

628
Jan
743
Feb
971
Mar
1085
Apr
1200
May
1257
Jun
1257
Jul
1200
Aug
1028
Sep
914
Oct
628
Nov
514
Dec

Based on 5.2 peak sun hours/day for Southeast (FL, GA, SC, NC, TX). Assumes south-facing panels, 14% system losses.

What If Your System Is Underperforming?

10% underperformance

You'd lose ~1,143 kWh/year

= ~$183/year in lost savings

25% underperformance

You'd lose ~2,857 kWh/year

= ~$457/year in lost savings

Studies suggest unmonitored systems can operate at 70-80% efficiency for extended periods before detection. That's $457-$548 lost every year you don't check.

Is your system actually producing 11,426 kWh?

Run a free health check to compare your actual production against this estimate. Takes 2 minutes. No account required.

Check My System Now

How We Calculate Expected Solar Production

This calculator uses the same methodology as the National Renewable Energy Laboratory's PVWatts tool, simplified for homeowners. We multiply your system size (kW) by your region's average peak sun hours, then apply a 14% system loss factor (the industry standard accounting for wiring, inverter efficiency, and temperature effects).

For systems older than one year, we apply a 0.5% annual degradation factor. This is the industry-accepted rate — most tier-1 panels guarantee at least 80% output after 25 years, which works out to about 0.5% per year.

Why Your Actual Production May Differ

This calculator provides a baseline estimate. Your actual production depends on:

  • Panel orientation: South-facing panels produce the most. East or west-facing systems produce 10-20% less.
  • Tilt angle: Panels tilted at your latitude produce the most annually. Flat or steep roofs reduce output.
  • Shading: Even partial shading from trees, chimneys, or neighboring buildings can reduce output by 10-40%.
  • Weather: Unusually cloudy years will produce less. This calculator uses long-term averages.
  • Equipment quality: Premium panels (SunPower, LG, REC) typically outperform budget panels.

How to Check Your Actual Production

Log into your SolarEdge or Enphase monitoring app and look at your monthly kWh totals. Compare them to the estimates above. If your actual production is consistently 15% or more below the estimate, something may be wrong with your system.

Run a free SolarDoctor health check to get an exact comparison of your actual vs. expected production based on your specific system size, location, and local weather data.