Plug-in solar, in plain words

Watt (W) — a rate, like miles per hour. A 400-watt panel produces 400 watts at its very best, in full noon sun, which is a small fraction of the year.

Kilowatt-hour (kWh) — an amount, like miles travelled. It's what your utility bills you for. A 400-watt panel running flat out for an hour makes 0.4 kWh. A California household uses roughly 500 to 800 kWh a month.

DC and AC — panels make direct current, your home runs on alternating current. Something has to convert between them.

Inverter — the thing that does that conversion.

Microinverter — a small inverter attached to one or two panels rather than a whole array. Plug-in kits use these. It's the expensive, safety-critical part.

String inverter — one big central inverter for many panels. Rooftop systems use these. Not relevant to you.

Branch circuit — the run of wiring from one breaker in your panel board to the outlets it serves. Your kit shares one with whatever else is plugged in nearby.

GFCI — ground fault circuit interrupter, the outlet with the test and reset buttons. Required outdoors. It cuts power if it detects current going somewhere it shouldn't.

Self-consumption — the share of what your panel makes that your home uses as it's made, rather than sending to the grid. The most important number in the whole calculation, and the one nobody asks about.

Export — power you send back to the grid. Under SB 868, worth nothing.

Anti-islanding — the safety feature that makes the device shut down when the grid goes down, so line workers aren't shocked by power from your balcony. Required. It's why you get no backup power.

Zero-export device — a setup with a meter that throttles the inverter so nothing ever flows to the grid. Loses you some production, gains you certainty about interconnection.

Interconnection — the formal process of getting a utility's permission to connect a generator to its grid. Rule 21 is the California tariff that governs it. SB 868 exempts plug-in devices from it.

Net metering / NEM 3.0 / net billing — the rules about what a utility pays you for exported power. California's current version, adopted in December 2022, pays new rooftop solar a fraction of the retail rate. It's why self-consumption matters so much and why plug-in solar is attractive: you're avoiding a 33-cent purchase, not making a 6-cent sale.

Time-of-use (TOU) — a rate plan where electricity costs different amounts at different hours. SCE's peak is typically 4pm to 9pm, when a panel makes almost nothing.

Base Services Charge — SCE's fixed monthly charge, around $24.15 for non-CARE customers, payable regardless of usage. Solar doesn't touch it.

CARE — California Alternate Rates for Energy, a discount for lower-income households. Worth checking if you haven't.

CCA — Community Choice Aggregator, a local body that buys your electricity while the utility still delivers it. Orange County Power Authority is one. It changes the generation part of your bill, not the wires.

IOU — investor-owned utility. SCE, SDG&E, PG&E. POU — publicly owned utility, like LADWP or SMUD. SB 868 covers both.

UL 1741 — the older safety standard for grid-interactive inverters. Real, but not the plug-in standard.

UL 3700 — the standard written specifically for plug-in photovoltaic equipment, launched January 2026. This is the one SB 868 effectively requires.

NRTL — nationally recognised testing laboratory. UL, CSA and Intertek (whose mark is ETL) are all NRTLs. A listing from any of them counts.

NEC / CEC — the National Electrical Code and the California Electrical Code. The rulebooks for wiring. SB 868 requires compliance with the current versions.

Solar Rights Act — California law (Civil Code §714, §714.1, §4746) limiting how much an HOA can restrict solar. Written around roof-mounted systems; its application to balcony devices is untested.

Davis-Stirling Act — the law governing California HOAs, including architectural review.

Irradiance — how much solar energy falls on a surface. NREL publishes it. It's the starting number in every savings calculation.

Tilt — the angle a panel is set at. Vertical on a railing is the worst common case and costs you nearly 40 percent.

Balkonkraftwerk — German for balcony power plant. Worth knowing because most of the useful data about this category is German.