How plug-in solar works: from sunlight to a smaller bill

The short answer: a plug-in solar kit is one or two solar panels and a microinverter, mounted on a railing, a patio or a ground stand and plugged into an outlet.^[source] It pushes power straight into your home's circuits, where it's used to meet your home's own demand, so you buy less power from your utility while the sun is out.^{[source][source]}

1. Step 1SunlightThe panels turn sunlight into DC power.
2. Step 2MicroinverterTurns DC into the AC power your home uses.
3. Step 3OutletThe kit plugs into an outlet on your home's circuits.
4. Step 4Your homeWhatever is running uses the solar power.
5. Step 5Your meterYou buy less power from your utility.

Extra powerPower your home isn't using flows out to the grid, and probably earns nothing.

Power outageThe kit switches itself off when the grid goes down. It isn't backup power.

Step by step

1. Sunlight hits the panels. Panels on a balcony rail, wall, patio or in the yard make power whenever the sun is on them.
2. The microinverter converts it. An inverter turns DC power into AC.^[source] AC is what your home's outlets and appliances run on.
3. The kit plugs into an outlet. SB 868 covers systems designed to connect to your home's wiring through a receptacle (an outlet).^[source] Kits certified under today's UL framework need a unique plug and a dedicated circuit, which in California means an electrician installs it.^[source] See Do I need an electrician?
4. Your home uses the power. The kit pushes power straight into your home's circuits.^[source] A kit makes little power, so it's used to meet your home's own demand: the fridge, a laptop, the lights.^[source]
5. You buy less from your utility. Every kWh your home takes from the kit is one you don't buy. A small kit offsets part of your daytime use, not your whole bill.^[source]

What happens to extra power

If the kit makes more than your home is using at that moment, the extra flows out to the grid. SB 868 waives the utility's interconnection process, but it doesn't promise to pay you for exported power.^[source] That's why our calculator values exported power at $0, and why a kit sized to what you use during the day saves the most. Running the dishwasher or laundry around midday helps (more on time-of-use rates).

What comes in a kit

• Solar panels, usually one or two.^[source]
• A microinverter, or one per panel. One kit Solar.com describes bundles four 300-watt panels, four microinverters, a smart gateway and mounting hardware.^[source] Inverters are also subject to a new federal rule (FCC inverter rule explained).
• A mount for a railing, a patio or a ground stand.^[source]
• A battery, sometimes. A battery is what lets you use your own power after sunset.^[source] It adds cost (batteries and outages).

Before you buy, check that the complete system is certified by UL or an equivalent nationally recognized testing laboratory.^[source] Our kit checker walks through it.

In a power outage

A qualifying kit must have a certified feature that stops it sending power into the grid during an outage.^[source] It switches off when the grid goes down, so it never sends power onto lines a utility crew is working on.^[source] A plug-in kit on its own isn't backup power.

What changes and what doesn't

• No utility approval. From Jan 1, 2027, a qualifying kit up to 1,200 W AC per home doesn't need an interconnection agreement or approval. Your utility may ask you to register it through a simple online form.^[source]
• City utilities too. The law also covers city and other public utilities, such as LADWP and SMUD.^[source]
• Your lease and HOA rules still apply. NRG Clean Power's explainer says SB 868 doesn't override your landlord or your HOA.^[source] Renters can use the letter in our renters guide.
• You keep your utility. You still buy most of your power from it, just less while the sun is out.

How much it might save

For a well-placed kit, our calculator expects 800 W of panels to make about 2.4 kWh a day, about 2.2 kWh of it used at home. On PG&E's standard rate, the example kit (800 W, $1,000) saves about $322 a year, assuming typical placement and that you use most of its power at home. Your result depends on your utility, rate plan and where the panels face: try the savings calculator, then run through the checklist before you buy.

Not electrical, legal or financial advice.