Key takeaways
- A south-facing, tilted 800 W kit saves about $165 a year at the US average rate — and $375+ in California.
- Payback ranges from about 2.5 years in high-rate states to 6+ years where electricity is cheap.
- Electricity price matters more than sunshine: Maine beats Arizona despite far less sun.
- A vertical railing mount cuts output by roughly 30%; an east- or west-facing one by about 18%.
- Only power you use at home counts — exported surplus earns nothing, so don't oversize.
Ask a balcony solar seller how much you'll save and you'll often hear "up to $50 a month." Ask a skeptic and you'll hear "a few dollars." Both can be true — the answer depends on where you live, where you hang the panels and how your household uses power.
Here's the honest math, with real numbers for real states.
The formula
Every savings estimate boils down to two steps.
1. How much electricity the system makes in a year:
kWh per year = system size (kW) × peak sun hours per day × 365 × losses × placement
- Peak sun hours average about 4 in New England and the Pacific Northwest, 4.5–5 across much of the country and 6+ in the desert Southwest.
- Losses (inverter, heat, wiring, dust) typically leave about 86% of the theoretical output.
- Placement depends on direction and tilt — more on that below.
2. What that electricity is worth to you:
Savings = kWh per year × share used at home × your price per kWh
The middle term is what most calculators skip. Plug-in solar laws exempt these systems from net metering, so electricity you export to the grid earns nothing. Only what your home consumes while the sun shines lowers your bill.
Savings for an 800 W kit, state by state
Assumptions: two 400 W panels facing south at about 30°, 80% of output used at home, a $900 kit, and each state's average residential price from the EIA for July 2026.
| State | Rate (¢/kWh) | Sun hours | Used per year | Saved per year | Payback |
|---|---|---|---|---|---|
| Hawaii | 48.00 | 5.5 | 1,105 kWh | $530 | 1.7 yrs |
| California | 33.61 | 5.6 | 1,125 kWh | $378 | 2.4 yrs |
| Massachusetts | 30.49 | 4.1 | 824 kWh | $251 | 3.6 yrs |
| New York | 29.90 | 3.9 | 784 kWh | $234 | 3.8 yrs |
| New Jersey | 25.19 | 4.3 | 864 kWh | $218 | 4.1 yrs |
| US average | 18.31 | 4.5 | 904 kWh | $166 | 5.4 yrs |
| Texas | 15.88 | 5.2 | 1,045 kWh | $166 | 5.4 yrs |
| Utah | 13.12 | 5.5 | 1,105 kWh | $145 | 6.2 yrs |
Every state's numbers are on its page in our law tracker, and you can change every assumption in the calculator.
Price beats sunshine
Look at Utah and Massachusetts. Utah gets a third more sun, but Massachusetts electricity costs more than twice as much — so the same kit saves $106 more a year in Massachusetts. When you're judging whether plug-in solar is worth it, start with your electricity bill, not the weather.
Placement: the factor you control
The table above assumes ideal placement. Real balconies are rarely ideal.
| Placement | Output vs. ideal |
|---|---|
| South, tilted ~30° | 100% |
| South-east or south-west | ~95% |
| East or west | ~82% |
| Flat on the ground or a flat roof | ~88% |
| Vertical on a south-facing railing | ~70% |
| North-facing | ~58% |
A vertical panel on a railing is the most common balcony setup and the least productive — about 30% below ideal over a year. It does relatively better in winter, when the sun is low, and much worse in summer. If your railing allows it, a mounting bracket that tilts panels outward by 20–30° recovers much of the loss.
Shade is worse than any of these. Even partial shade from a balcony above, a tree or a neighboring building can halve output for the hours it falls on the panels. See our guide to choosing the best direction and angle.
Self-consumption: why bigger isn't always better
A home's base load is the power it draws all the time: refrigerator and freezer cycling, router, modem, standby electronics, ventilation. For a typical apartment it's 100–300 W; for a house, often 200–500 W.
On a sunny midday, an 800 W kit can produce 600–700 W. If your home is only drawing 250 W, the rest flows out to the grid — for free. That's why:
- 800 W is the sweet spot for most households.
- 1,200 W makes sense for larger homes, people who work from home, or homes that run dishwashers, laundry or EV charging during the day.
- A battery can raise self-consumption from about 80% to 95%+ by storing the midday surplus for the evening. Whether that pays off is covered in our battery guide.
Shift your loads
You can raise self-consumption for free: run the dishwasher, washing machine and dryer around midday; charge laptops, e-bikes and power tools when the sun is out; pre-cool your home in the early afternoon.
Monthly savings: what to expect across the year
Solar output follows the seasons. In the US, a fixed panel typically produces about twice as much in June as in December. For an 800 W kit saving $166 a year, expect roughly $17–$18 in early summer and $8–$9 in mid-winter. Don't judge your system by its first December.
Time-of-use rates change the math
If your utility charges more in the late afternoon and evening — common in California and increasingly elsewhere — midday solar is worth less than the average rate, and late-afternoon solar is worth more. Two strategies help:
- Face panels west to shift production toward the expensive hours.
- Add a small battery to move midday energy into the evening peak.
What the "up to $50 a month" claims assume
Headlines quoting $40–$50 a month typically assume a 1,200 W system in a high-rate state, ideal placement and almost all output consumed at home. That's achievable in California or Hawaii with a battery, but it's the best case — not the typical one.
Lifetime value
Panels are typically warrantied for 25 years and microinverters for 10–25. Over 25 years, ignoring panel degradation and future rate increases (which roughly offset each other), our US-average example saves about $4,140 on a $900 kit — a net gain of about $3,240. In California, the 25-year net is about $8,550.
The bottom line
- In high-rate states (above about 25¢/kWh), a well-placed 800 W kit pays for itself in two to four years. It's one of the best returns available to a renter.
- Near the national average, payback is five to six years — reasonable, but placement and self-consumption matter.
- In low-rate states, plug-in solar is more about energy independence than fast returns.
Run your own numbers in the calculator, then check whether it's legal in your state.
Frequently asked questions
How much does an 800 W balcony solar system save per month?
At the July 2026 US average rate of 18.31¢/kWh, about $14 a month averaged over the year — more in summer, less in winter. In California, Massachusetts or New York, $19–$32 a month is realistic for a well-placed kit.
Is balcony solar worth it?
It's worth it if you pay above-average electricity rates, have a spot with at least four to five hours of direct sun, and can use most of the output during the day. In those conditions, a kit pays for itself in three to five years and keeps saving for twenty or more.
How many kWh does an 800 W solar panel kit produce?
Roughly 900 to 1,600 kWh a year in the continental US when facing south at a good tilt, depending on location. Vertical railing mounting reduces that by about 30%.
Does plug-in solar increase my home's value?
Generally no — it's portable equipment that you take with you when you move, unlike rooftop solar.