How many solar panels for 500 kWh per month?
About 12 panels at 400 watts each, a 4.8 kW system, under the national-average 4.5 peak sun hours. This page is sized from a 500 kWh monthly bill, not from house square footage. Sun moves the count from 9 panels in the desert Southwest to 14 in the cloudiest states, and panel wattage trades count against roof area. Both tables below; your state in the picker.
Panel count by sun and wattage
Counts cover 500 kWh fully, rounded up to whole panels, with the 0.77 derate from rated watts to real output (methodology). Bold is the US-average column.
| Peak sun hours | 350W panels | 400W panels | 450W panels |
|---|---|---|---|
| 4.0 h | 16 | 14 | 12 |
| 4.5 h (US avg) | 14 | 12 | 11 |
| 5.0 h | 13 | 11 | 10 |
| 5.5 h | 12 | 10 | 9 |
| 6.0 h | 11 | 9 | 8 |
| 6.5 h | 10 | 9 | 8 |
Same bill, six real states
| State | Sun | Panels (400W) | System |
|---|---|---|---|
| Arizona | 6.5 h | 9 panels | 3.6 kW |
| Texas | 5.3 h | 11 panels | 4.4 kW |
| Florida | 5.2 h | 11 panels | 4.4 kW |
| Missouri | 4.6 h | 12 panels | 4.8 kW |
| New York | 3.9 h | 14 panels | 5.6 kW |
| Washington | 3.8 h | 15 panels | 6 kW |
What a 500 kWh household looks like
Five hundred kWh a month is a small footprint: an efficient apartment-sized home, a well-insulated house with gas heat and gas hot water, or a snowbird place that sits empty half the week. If you are planning to electrify anything later, an EV or a heat pump, size for the bill you are about to have rather than the one in front of you.
The shape of the year matters as much as the total down here. A 500 kWh house is nearly always one with gas heat and gas hot water, and that combination flattens the bill: January and July land within about a hundred kWh of each other, which makes a single month's statement an unusually honest proxy. Houses with electric heat never behave that way, and a one-month sample from one of those is off by a factor rather than a rounding. At 12 panels the array is also small enough to be a single string on a single inverter input, so the electrical design stays boring. Boring is the goal.
Questions people ask
How many solar panels do I need for 500 kWh per month?
About 12 400-watt panels (a 4.8 kW system) at the national-average 4.5 peak sun hours, after the 0.77 real-world output derate. Strong desert sun brings it down to 9; cloudy-state sun pushes it to 14. The tables on this page break it out by sun figure and panel wattage.
What system size covers 500 kWh a month?
Roughly 4.7 kW of DC capacity at average US sun; we round panels up, so the quoted 4.8 kW covers it with a little margin. In sunnier states the same bill takes proportionally less capacity, which is the whole reason the per-state figures matter.
Do I have to cover 100% of the bill?
No, and often you shouldn’t. Utilities with poor net-metering rates make the last 20% of offset the worst-value panels on the roof, and some cap system size at your historical usage anyway. Sizing to 70-90% of the bill is a normal, defensible design choice; covering every kWh is only automatic where net metering pays retail.
Can I size a 500 kWh system from a single month's bill?
Unusually, yes, provided the house heats with gas and makes hot water with gas. That combination keeps January and July within about a hundred kWh of each other, so any month sits close to the average. If anything in the house runs on electric resistance heat, no: one winter month will be roughly double a shoulder month, and sizing from it buys panels for a bill you only have twice a year.