Quick answer: Plug-in solar is worth it if you live in a state that allows it, pay an above-average electricity rate, have a sunny spot, and your home uses power steadily during the day. In that case a small kit can pay for itself in roughly 3 to 6 years. It is a poor deal if your spot is shaded, your daytime use is very low, or you pay a cheap rate, because most laws pay nothing for the power you send back to the grid.
Plug-in solar has had a lot of hype. Here is the math without the marketing, so you can run it with your own numbers. If you are new to the topic, read our complete plug-in solar guide first.
Step 1: Estimate what the kit will produce
Yearly kWh ≈ kit watts ÷ 1,000 × peak sun hours × 365 × system factor
- Peak sun hours: roughly 3.5 to 4.5 in much of the northern U.S. and 5 to 6 in the Southwest, as yearly averages.
- System factor: our estimate of real-world losses from inverter efficiency, heat, dirt, shade and angle. Use about 0.75 for a well-angled, unshaded panel and 0.45 for a panel hanging flat on a balcony railing.
Step 2: Find out how much of it you will actually use
This is the step most savings calculators skip. In most states, a plug-in kit earns nothing for exports. So the only power that saves you money is power your home uses at the moment it is produced.
Your daytime base load is the power your home draws all the time: fridge, freezer, router, standby electronics, maybe a dehumidifier or a home office. Many homes draw somewhere between 150 and 400 watts around the clock, but yours could be very different. The best way to know is to check your utility’s hourly usage data online, or use a plug-in energy monitor.
If your base load is 200 watts and your kit produces 700 watts at midday, most of the midday output is exported for free. In that case a smaller kit, or one with a battery, will pay back faster than the biggest legal kit.
Step 3: Multiply by your electricity rate
Use the price per kWh on your bill, including delivery charges. The U.S. average residential price is forecast at about 18.2¢/kWh for 2026, according to the Energy Information Administration, but rates in California, New England and Hawaii are far higher.
Payback examples
These examples assume you use all the power produced. They are estimates, not promises.
| Scenario | Yearly output | Rate | Yearly savings | Payback on a $500 kit | Payback on a $1,000 kit |
|---|---|---|---|---|---|
| 800 W, 4 sun hours, well angled (0.75) | 876 kWh | 18.2¢ | about $160 | about 3 years | about 6 years |
| 800 W, 4 sun hours, balcony railing (0.45) | 526 kWh | 18.2¢ | about $96 | about 5 years | about 10 years |
| 800 W, 5 sun hours, angled (0.65) | 949 kWh | 30¢ | about $285 | under 2 years | about 3.5 years |
To calculate your own payback: kit price ÷ yearly savings = years to break even.
Who should buy plug-in solar
- You live in a state where plug-in solar is legal and the law is already in effect.
- You pay more than the national average per kWh.
- You have an unshaded south-, southeast- or southwest-facing spot.
- Someone is home during the day, or your home has steady daytime loads.
- You rent or cannot install rooftop solar, and want something you can take with you.
Who should skip it (for now)
- Your state has no plug-in law yet, or the law has not taken effect.
- Your only spot is shaded or faces north.
- Your daytime use is very low and you would export most of the output.
- Your main goal is power during blackouts. A plug-in kit without a battery shuts off during outages; look at portable power stations or home battery backup instead.
Ways to improve the numbers
- Right-size the kit to your daytime base load instead of the legal maximum.
- Angle the panels toward the sun if your mounting allows it; a vertical panel loses a lot of output.
- Shift flexible loads such as the dishwasher, laundry or charging to sunny hours.
- Consider a kit with a battery if you export a lot at midday, but check that the added cost pays back.
Sources
- U.S. Energy Information Administration, Short-Term Energy Outlook.
- State laws summarized in our state-by-state guide.
*Last checked: November 5, 2026. All savings and payback figures are estimates based on the assumptions shown.*