Balcony Solar Atlas

Balcony solar calculator

See what a plug-in kit would produce and save where you live, and whether your state allows it. The biggest factors are your electricity price, which way your railing faces, and how much of the output your home uses.

Estimates update as you change any field. Nothing you enter leaves your browser.

Which way does your balcony or railing face?
Pays for itself in
–
Yearly savings
–
Yearly production
–
Share you use yourself
–
10-year net savings
–
Orientation factor
–

How to fill it in

  • Facing. Stand on the balcony looking out. A phone compass app tells you the direction. If it is between two options, pick the closer one.
  • Mounting. Most railing kits hang the panels vertically. A tilting bracket or stand makes much more, if your building allows it.
  • Always-on load. What your home draws when nothing is actively being used: fridge, router, standby electronics. 150–300 W is common. Your smart meter's lowest daytime hourly reading is a good guide.
  • Inverter limit. The microinverter's maximum AC output, printed on its label. Most state laws cap it at 1,200 W.

Why the share you use matters

Plug-in kits generally earn nothing for power that flows back to the grid, so the calculator only counts the energy your home uses at the moment it is produced.

Share of solar output you use yourself, by household background load When your home's constant daytime draw is about 30 percent of the kit's peak output, you use about 58 percent of what it makes. At 80 percent or more, nearly all of it. 0% 25% 50% 75% 100% 0×0.5×1×1.5×2×+ Constant daytime household draw ÷ kit peak output ~215 W always-on load, 800 W kit: about 58% used
Hourly model on typical-year weather (Greensboro, NC, 35° south-facing array). Assumes a constant background load and no credit for power sent to the grid, which matches the plug-in laws in Vermont and Maine. Real homes vary through the day, so treat this as a guide.

What this estimate does not include

  • Time-of-use rates. If your midday price is lower than average, savings will be lower.
  • Rising electricity prices. We hold prices flat, which understates long-term savings if rates keep climbing. EIA data show the US average residential price rose from 17.0 to 18.2 cents per kWh between the first eight months of 2025 and 2026.
  • Snow, unusual shading patterns and panel faults.

Data: U.S. EIA, Electric Power Monthly, Table 5.6.B (YTD through August 2026); Peak sun hours by state (NREL PVWatts v8, 20° tilt, largest city), TheGreenWatt; orientation factors and self-use curve modeled by Balcony Solar Atlas with pvlib. Full method.