- Rooftop systems are 5-15 times larger and cheaper per watt, but cost $15,000-30,000 upfront in the US.
- Plug-in kits cost $400-1,500, need no installer and move with you.
- If you own a house with a sunny roof and plan to stay, rooftop usually wins on lifetime savings.
- If you rent, have no roof, or want a small low-risk start, plug-in wins.
Both systems use the same basic technology, so the choice comes down to your home, your budget and how long you will stay. Here is how they compare.
In this article
Side-by-side comparison
| Plug-in / balcony | Rooftop | |
|---|---|---|
| Typical size | 0.4-1.2 kW | 6-12 kW |
| Upfront cost (US) | $400-2,000 | $15,000-30,000 before incentives |
| Cost per watt | ~$1.00-2.00 | ~$2.50-3.50 installed |
| Installation | DIY in an hour or two | Professional crew, permits, inspection |
| Approval | None or a simple notification (where legal) | Interconnection agreement, weeks to months |
| Share of home use covered | 5-20% | 60-100% |
| Export credits | Usually none | Net metering or export tariff in many places |
| Portability | Take it with you | Stays with the house |
| Renter-friendly | Yes, with landlord agreement | No |
Wait, isn’t plug-in cheaper per watt?
It can look that way, because plug-in kits skip labor, permits and sales commissions, which make up much of a rooftop system’s price. But rooftop panels usually sit at a better angle, have more space and qualify for export credits. So the value per watt is often higher on a roof, and rooftop systems in many places also benefit from local incentives.
In the US, the federal 30% residential tax credit for rooftop solar expired on December 31, 2025, which raised the effective cost of rooftop systems for homeowners in 2026. That made the gap between the two options narrower than it used to be.
When rooftop solar wins
- You own a house with a sunny, unshaded roof in good condition.
- You plan to stay at least 8-10 years.
- Your utility offers net metering or a fair export rate.
- You use a lot of electricity: EV charging, heat pump, pool pump.
When plug-in solar wins
- You rent or live in an apartment or condo.
- Your roof is shaded, too small, or needs replacing soon.
- You might move within a few years.
- You want to start small and learn how solar works before a big commitment.
- Your state or country has a plug-in law but you cannot get rooftop approval.
Can you have both?
Usually not in the US: most plug-in laws say a qualifying device should not be combined with a net-metered rooftop system on the same meter, and exceeding the cap defeats the purpose. Some homeowners use a plug-in kit on a detached garage or shed with its own circuit while they save up for a roof system. Check your state’s rules and your rooftop interconnection agreement first.
Worked example
A household in Pennsylvania using 10,000 kWh a year at 18 cents per kWh:
- 800 W plug-in kit on a south fence, tilted: ~1,000 kWh/year, 80% self-used → about $145 saved a year for a $900 kit. Payback around six years.
- 8 kW rooftop system: ~10,000 kWh/year covering most use, with partial export credit → roughly $1,400-1,700 saved a year for about $24,000. Payback around 14-17 years without incentives, shorter with them.
The rooftop system saves ten times more each year but costs more than 25 times as much upfront. Which is “better” depends on your horizon and cash. For quick numbers, try the calculator and read is balcony solar worth it?
Questions to ask yourself
- Do I own the roof, and will I stay? If not, rooftop solar is usually off the table.
- How much electricity do I use? Under 4,000 kWh a year, a plug-in kit covers a meaningful share. Above 10,000 kWh, it barely dents the bill.
- What does my utility pay for exports? Good export rates favor rooftop; none at all favors a small kit matched to daytime use.
- How much cash can I tie up? A plug-in kit is a few hundred dollars; rooftop is a car-sized purchase or a long loan.
- Is my roof in good shape? Replacing a roof after installing panels is expensive. If the roof needs work soon, a plug-in kit is a sensible bridge.
Frequently asked questions
Is plug-in solar a good “trial” before rooftop?
Yes. It shows you how much your site produces and how your household uses daytime power, which helps size a future rooftop system.
Can I move a rooftop system?
Technically, but it is costly and rarely worth it. A plug-in kit is designed to move with you.
Which is more reliable?
Both use the same panel technology. Rooftop systems are professionally installed and inspected; plug-in reliability depends heavily on your mounting and outlet.
Does rooftop solar still qualify for a federal tax credit?
For homeowners, the 30% residential credit expired at the end of 2025. What’s left in 2026.