Solar, Batteries & Renewable Energy

How home solar and batteries work

Solar panels turn sunlight into direct current (DC) electricity (DOE). An inverter turns that into the alternating current (AC) your home and the grid use (DOE). Your home uses the solar power first; extra can charge a battery or flow out to the grid through a two-way meter. At night you draw from the battery or the grid.

Inverters: string, micro and hybrid

The inverter is one of the most important parts of a solar system. Here are the common types for homes:

Battery systems that keep power on in an outage rely on inverters designed to run without the grid. Grid-tied solar alone normally shuts down when the grid does.

California net billing (NEM 3.0) and why batteries matter

For PG&E customers, new solar interconnection applications since April 15, 2023 go on the Net Billing Tariff, which PG&E calls the Solar Billing Plan. In plain words:

• Your own use comes first. Solar power serves your home before anything goes to the grid.
• Exports earn hourly values. Energy you send out is credited at values set from the CPUC’s avoided cost calculator. They change by month and hour, are usually below the retail price, and can be higher on some late-summer evenings (CPUC).
• Batteries add value. The CPUC notes that storing solar and using or exporting it at high-value hours helps get the most from a system.
• Electrification rate. Net billing customers go on an electrification time-of-use rate (E-ELEC for PG&E residential customers, per Schedule NBT).
• Monthly bills, yearly true-up. You pay charges monthly and settle energy at an annual true-up.
• Lock-ins. Per the CPUC, residential customers applying through the end of 2027 lock in their export value schedule for nine years, and PG&E and SCE residential customers applying before the end of 2027 get an extra export adder (not for solar required by the building code).

Already on an older plan? Be careful before adding panels: per PG&E, increasing system size by 1 kW or 10% can move you to the Solar Billing Plan. Repairs and like-for-like replacements are a different story; ask before you change anything. More in our net billing guide.

Sizing basics: kW vs. kWh

Two units cover almost everything. kW (kilowatts) is power: how much you’re using or making right now. kWh (kilowatt-hours) is energy: how much over time. A 1 kW load running for 10 hours uses 10 kWh.

For backup, a simple estimate is usable kWh divided by the average kW you’ll draw. A battery with 10 kWh usable running about 1 kW of essentials lasts roughly 10 hours, before any solar recharge. Try our battery backup calculator for your own numbers. For solar production, the national lab’s free PVWatts tool can estimate what panels would make at your address; real proposals should show their assumptions.

Main panel upgrades and the 120% rule

When solar back-feeds a panel through a breaker, the code limits how much can go onto the busbar. Paraphrasing NEC 705.12: 125% of the inverter’s output current plus the main breaker rating shouldn’t exceed 120% of the busbar rating, with the solar breaker at the opposite end from the main.

Example: a 200 A busbar with a 200 A main leaves 40 A of room (240 − 200). Divided by 1.25, that’s about 32 A of continuous inverter output. Larger systems or a battery can push past that.

If you’re over, the options include a smaller main breaker (only if a load calculation says the home can live with it), a connection on the supply side of the main, a panel with a larger busbar, or a listed power control system. Older or problem panels are often worth replacing anyway. More in our panel readiness guide, the solar code article with a 120% calculator, and panel upgrades.

Rapid shutdown and safety labels

Rooftop solar keeps making voltage whenever the sun is up. Rapid shutdown (NEC 690.12, paraphrased) requires roof-mounted systems to be able to drop the voltage in conductors on and near the array quickly when a shutdown switch is used, to protect firefighters. It’s why you’ll see a labeled switch and signs near the service. When an inverter or panel-level device is replaced, we make sure rapid shutdown still works with the new equipment.

Solar repair and inverter replacement

Solar should mostly take care of itself, so when production drops it’s easy not to notice. Signs something’s wrong:

• The app or monitoring shows zero or much lower production on sunny days, or has stopped reporting.
• An inverter light shows red, orange or an error code.
• A solar breaker or disconnect is off or keeps tripping.
• Your bill went up and nothing else changed.

We check the simple things first: breakers, disconnects and the monitoring connection. Then connectors, wiring, ground faults and the inverter itself. If the inverter has failed, we look for compatible replacement equipment, keep rapid shutdown working, and handle the permit and any utility paperwork. Inverters and panel-level electronics often have warranties, so dig out your paperwork, and we’ll help you figure out what’s covered.

Re-roofing? Panels usually need to come off and go back on. We can remove, store if needed, and reinstall them, and check the wiring while it’s exposed.

Adding a battery to existing solar

Batteries can be added later in two main ways. AC-coupled batteries have their own inverter and connect on the AC side, so they work with most existing systems. DC-coupled batteries share a hybrid inverter with the panels. As DOE puts it, solar can charge a battery directly over DC or after conversion to AC.

• Backed-up loads panel or whole home? Many systems back up a separate panel with essentials; whole-home backup needs more battery and planning.
• Panel room. Another back-fed breaker can run into the 120% rule.
• Location. Fire and building codes limit where and how much battery can go in a home; see NEC 706 and NFPA 855 basics.
• Utility plan. Adding storage needs a PG&E interconnection application, and older-plan customers should ask how it affects their plan.

EVs and solar

An EV is one of the bigger loads a home can add, and a natural match for solar. Charging at midday when the sun is strong, or at the cheapest time-of-use hours, gets the most from your system. Load management or power-sharing chargers can often avoid a panel upgrade. Some newer cars and chargers can send power back to a home in an outage; that only works with equipment made and approved for it and the same safe disconnect from the grid as any backup source. See EV charger installation and can my panel handle an EV charger?.

PSPS and wildfire outages

In the foothills we all know the drill. Public Safety Power Shutoffs can turn power off ahead of high fire-risk weather, sometimes for more than a day. A few honest thoughts from us:

• Battery plus solar is quiet, needs no fuel and recharges when the sun is out, but a few cloudy days or big loads can drain it.
• A generator runs as long as it has fuel, which suits long outages. Some homes use both.
• Pick your essentials: fridge, lights, internet, well pump, medical equipment. That decides the size.
• Never back-feed a home with a generator through an outlet. Use a transfer switch or interlock.

More on generators and battery backup and standby generator vs battery.

Simple maintenance

Renewable energy basics: sun, wind, water and storage

• Solar. Photovoltaic panels turn sunlight straight into electricity (DOE).
• Wind. Wind turns turbine blades around a rotor, which spins a generator (DOE).
• Hydro. Flowing water spins turbines connected to generators (DOE). This one is part of our region’s story: per PG&E, its hydroelectric system traces back to the Gold Rush, draws on more than 100 reservoirs mostly high in the Sierra Nevada, and has 67 powerhouses. Long-distance power in California started with Sierra water, which we cover in our history of electricity.
• Storage. Batteries, at home and at grid scale, save energy for when the sun is down and the wind is still.

Incentives: where things stand (Nov 2026)

We want to be straight with you, because a lot of older articles are now out of date:

• Federal credit. According to the IRS, the Residential Clean Energy Credit doesn’t apply to expenditures made after December 31, 2025, and an expenditure counts as made when installation is completed.
• SGIP. As of early November 2026, the SGIP program metrics showed the general-market residential storage budget closed, with income-qualified equity funding limited and waitlisted in some areas, including PG&E.

Please check those official sites, or a tax professional, before counting on any incentive. We don’t sell incentives, and we never build a quote around one that may not exist.

What working with us looks like

• Honest numbersNo invented savings. We show our assumptions and point you to the official sources.
• Safety firstRapid shutdown, labels, proper disconnects and a safe way to back up your home.
• Permits and PG&E handledPermit, inspection, interconnection and PTO, start to finish.
• A phone that gets answeredWalter answers his own phone nearly all the time, 24/7.