One question, answered straight
How many solar panels do I actually need?
Divide your annual electric usage in kWh by your state's average annual production per kW (1,350 in Missouri, 1,400 in Kansas) to get your system size in kW. Divide that by your panel's wattage, typically 400 to 440 watts, to get panel count. A typical 14,400 kWh Missouri home needs about a 10.7 kW system, roughly 25 to 27 panels.
By Joshua Hayeslip · Founder and CEO, Solar Assure
The formula
Three numbers, in this order.
Production figures are Solar Assure's own state averages, unchanged from our calculator's defaults; see disclosures. Your actual roof orientation, tilt, and shading change your real number, which is why a quote includes an Aurora Solar production model specific to your address.
Worked examples
Missouri and Kansas, side by side.
| Home | Annual usage | Production factor | System size | Panel count (400W) |
|---|---|---|---|---|
| Typical Missouri home | 14,400 kWh | 1,350 kWh/kW | ~10.7 kW | ~27 panels |
| Smaller Missouri home | 10,800 kWh | 1,350 kWh/kW | ~8.0 kW | ~20 panels |
| Typical Kansas home | 14,000 kWh | 1,400 kWh/kW | ~10.0 kW | ~25 panels |
| Larger Kansas home | 16,000 kWh | 1,400 kWh/kW | ~11.4 kW | ~29 panels |
Kansas note: because excess exported kWh are credited at wholesale, not retail, under K.S.A. 66-1263, Solar Assure sizes Kansas systems a little closer to actual usage rather than rounding up, to avoid overproducing into the low wholesale credit. See our Kansas payback math for why that matters.
Common questions
Sizing, answered honestly.
Should I size for 100% of my usage?
In Missouri, yes, generally: RSMo 386.890 credits exports at the full retail rate within the billing cycle, so sizing close to 100 percent of annual usage captures the most value. In Kansas, sizing slightly under 100 percent usually performs better, because excess production is credited at the wholesale system-average rate under K.S.A. 66-1263, not retail.
What if my roof can't fit the panel count I calculated?
Higher-wattage panels (closer to 440W) fit more capacity into the same roof area than lower-wattage panels. Solar Assure's Aurora Solar design accounts for your actual usable roof area, orientation, and shading before recommending a final panel count and layout.
Josh personally reviews the production model on every Solar Assure quote before it goes to a customer. The formula on this page is the same one used to build our online calculator's defaults, not a separate marketing number.
Related Guides