Balcony solar calculators
6 calculators that answer the questions the product listings avoid — built on stated assumptions you can check, not round numbers from nowhere.
The short version
A plug-in balcony solar kit rated 800W realistically delivers about 490W on a south-facing railing, or roughly 751 kWh a year. At the US average residential rate of 18.34¢/kWh, that is about $138 a year, so a $699 kit pays for itself in roughly 5.1 yrs. It is explicitly legal in 4 of 51 US jurisdictions and in a gray zone — not banned — in 39 more.
Those are national averages. Your orientation, shade, electricity rate and how much power your home draws during daylight all move the answer, which is what the five calculators below are for.
The calculators
Is it legal in my state?
Pick your state for a straight answer, plus a tracker of all 51 US jurisdictions and what the law says today.
4 states with an explicit law
Open the toolWhat will my balcony actually produce?
An 800W kit does not make 800W. Orientation and shade decide how close you get.
A south-facing 800W kit really makes ~490W
Open the toolWhat will it actually cover?
Pick the appliances you run and see how much of your daytime electricity a kit offsets — and how much it spills to the grid unpaid.
Sizes for least waste, not biggest kit
Open the toolBalcony vs rooftop payback
Why not just get real solar? Here is the trade-off on your own electricity price.
Side-by-side cost, savings and payback
Open the toolWhich kit do I need?
Three questions about your balcony, then we rule out everything that will not fit it.
Matched to space, tenure and orientation
Open the toolBuild it from parts
Pick panels, a microinverter and a mount. Every pairing gets a computed verdict from the datasheets: voltage windows, state watt caps, circuit limits.
PCPartPicker, for plug-in solar
Open the tool
Which calculator answers which question
| Your question | Use |
|---|---|
| Am I allowed to plug solar into my own outlet? | Is it legal in my state? |
| How many kWh will an 800W kit really make? | What will my balcony actually produce? |
| How much of my electricity bill does it offset? | What will it actually cover? |
| Should I just get rooftop solar instead? | Balcony vs rooftop payback |
| Which kit physically fits my balcony? | Which kit do I need? |
| Will this panel work with that inverter — and is it legal here? | Build it from parts |
The four numbers that decide whether balcony solar is worth it
- 1. What the panels really deliver, not what the box says
- A rating is measured under laboratory irradiance with the panel at an ideal angle. Hung vertically on a railing, an 800W kit delivers around 490W — about 61% of the label. Any site quoting the rated figure as your output is quoting the wrong number.
- 2. Your electricity rate, which decides everything
- The same kit is worth several times more in an expensive state than a cheap one. Residential rates across the 51 jurisdictions we track span from about 12.3¢ to 52.0¢ per kWh. This is the single biggest variable, and it has nothing to do with the hardware.
- 3. How much you use while the sun is up
- A grid-tied kit has no battery. It offsets what your home is drawing at that moment; anything more flows back to the grid, and most US utilities pay a plug-in system nothing for it. A household that is empty all day captures a fraction of what it generates — which is why a bigger kit is not automatically a better buy.
- 4. Whether you are allowed to install it
- State law is usually silent. In most of the US the binding rules are your utility’s interconnection terms and your lease or HOA agreement, not the statute book. Check that before you buy hardware, not after.
Common questions
How much electricity does a balcony solar kit actually produce?
About 751 kWh a year for an 800W kit on a south-facing, unshaded railing — roughly 2.1 kWh a day. The panels are rated at 800W under laboratory conditions; hung vertically on a railing at 4.2 peak sun hours and 85% system efficiency, the realistic figure is closer to 490W. East, west or shaded balconies produce substantially less.
How much money does balcony solar save per year?
At the US average residential rate of 18.34¢/kWh (EIA, May 2026 data), 751 kWh is worth about $138 a year — but only if your home is drawing power while the panels are producing. A grid-tied kit with no battery cannot store the surplus, and most US utilities pay a plug-in system nothing for exported energy, so a household with a small daytime load captures less than it generates.
How long does a balcony solar kit take to pay for itself?
About 5.1 yrs for a $699 800W kit at the US average electricity price. The variable that moves this most is not the hardware, it is your rate: the same kit pays back in roughly a third of the time in Hawaii as it does in the cheapest states. Shade and orientation matter more than brand.
Is plug-in balcony solar legal in the United States?
4 of the 51 US jurisdictions have a statute that explicitly permits it — Maine (LD 1730 (2026)) and Maryland (HB 1532 (2026), Chapter 353) and Utah (HB 340 (2025)) and Vermont (S.202 / Act 149 (2026)). 8 has legislation passed but not yet in force. The remaining 39 have no specific law either way, which is a gray zone rather than a ban: your utility's interconnection terms and your lease or HOA agreement are what decide. Last reviewed August 31, 2026.
Do these calculators require an account or an email address?
No. All five run entirely in your browser, there is no sign-up, and nothing you enter is transmitted or stored. There is no lead form and your details are never passed to an installer.
Where do the numbers in these tools come from?
Sun-hour data from NREL, residential electricity prices from EIA state averages, and legal status from state statute and published utility tariffs, each with the date it was last checked. Every tool prints its own assumptions underneath the result. We do not test hardware, so specifications are quoted from manufacturer datasheets rather than from our own measurements.
Figures on this page are computed from the same assumptions the calculators use: 4.2 peak sun hours, 85% system efficiency, and residential electricity prices from EIA state averages. Legality last reviewed August 31, 2026. See how we research for where each input comes from.