Plug-in vs rooftop solar: cost, savings and who each one suits

The short answer: plug-in solar is a small, low-cost start for people who can't put panels on a roof, and it saves money only on the power you use as it's made. Rooftop solar costs far more up front but can cover much more of a home's use.

What each costs per watt

Bright Saver, a nonprofit that sells plug-in kits (some of them in our kit tracker), compared prices in a white paper published in October 2025, before SB 868 passed. These are Bright Saver's figures, not ours:^[source]

Price per watt by system type, Bright Saver estimates, October 2025

System	Size	Total price	Price per watt
Plug-in kit sold nationwideIncludes backfeed-prevention hardware and its installation	800 W	$2,375	$2.97
Plug-in kit in Utah after H.B. 340Self-installed, no backfeed-prevention hardware, ground mount included	800 W	$1,263	$1.58
Plug-in kit in GermanyThe same product as the Utah kit; not sold in the U.S.	800 W	$496	$0.62
Rooftop solar, U.S. averageNREL 2024 data scaled to an 8 kW system, no incentives	8 kW	$25,200	$3.15

• Kits sold nationwide cost about the same per watt as rooftop solar ($2.97 per watt against $3.15 per watt), because they needed backfeed-prevention hardware and an electrician to install it, Bright Saver says.^[source]
• In Utah, where a 2025 law let small kits skip the utility's interconnection process, Bright Saver found a kit at $1.58 per watt, about half as much.^[source] More in why kit prices may fall.
• In Germany, the same kit sold for $0.62 per watt.^[source]

Prices exclude tax credits and incentives. California prices under SB 868 may differ: check current prices in our kit tracker.

Who each one suits

Bright Saver estimates that about 70% of U.S. households can't use rooftop solar, because they rent, their roof is unsuitable, or they can't afford or finance a system.^[source] It points to these groups as the ones plug-in solar can reach:^[source]

• Renters and apartment or condo dwellers, who don't control the roof. You still need your landlord's or HOA's written permission (see our renters guide).
• Homeowners whose roof is shaded, old or badly oriented.
• Seniors and others on fixed incomes, who want a small, low-cost start.
• People in hot places, where a kit can offset some daytime air-conditioning use.

For homeowners with a usable roof, pv magazine's California guide suggests getting a rooftop-plus-storage assessment first, then deciding whether a plug-in kit fills a gap.^[source] Its author runs a company that installs rooftop solar and batteries. If you already have rooftop solar, read adding plug-in solar when you already have rooftop solar first.

How the savings work

• Plug-in solar: SB 868 doesn't guarantee any payment for power a kit sends to the grid, so treat exported power as worth nothing and size the kit to your daytime use.^[source] Our calculator works this way.
• Rooftop solar: under California's net billing, power you export earns much less than under the old net metering. Most of the value comes from using your own power, including after sunset, which generally needs a battery.^[source]
• On CARE or FERA? Pick your discount in the calculator. A discounted rate means each kWh you save is worth a little less, so the payback is longer. More in CARE and FERA discounts and plug-in solar.