PG&E blackouts and solar panels: what you need to know

Pacific Gas and Electric (PG&E) has been doing planned blackouts through the wildfire season in 2019 as an emergency measure to avoid deadly wirefires like the Camp Fire of 2018 that killed 85 people and burned over 150,000 acres. Today’s planned blackout will be largest yet: over 800,000 customers will be affected.

The Camp Fire of 2018 was caused by a faulty PG&E power transmission line in Butte County. A fallen PG&E power line sparked a fire on the morning of November 8, and within two days more than 6,700 structures had already been burned.

By de-energizing power lines during times when the wirefire risk is extremely high - a combination of dry conditions and high winds - PG&E hopes to avoid a repeat of the deadly Camp Fire.

Today’s planned blackout is the largest yet, but PG&E customers should expect that this is the new norm. Upgrading energy infrastructure to prevent the kind of failures that caused the Camp Fire will be expensive and take time. If you’re a PG&E customer, you might be wondering if you can do anything to protect yourself from reoccurring blackouts in the future - like adding solar panels to your home.

How solar panels work in blackouts

Unless you have batteries, your solar home will also go dark in a blackout. Here’s why.

The vast majority of solar homeowners are connected to the grid. This means that the home uses solar electricity when it’s available, and grid power when it’s not. When the solar panels generate more electricity than the home needs, the excess power is sent into the grid where it can be used by neighboring homes.

The key piece of equipment to make this system work is the home’s solar inverter. The inverter takes the direct current (DC) power generated by the solar panels and converts it into alternating current (AC) that the home can use.

In North America, AC power operates at a frequency of 60 hertz. This means that the power cycles between positive and negative on a precise interval of 60 times per second. If a solar inverter is grid-tied, it must synchronize exactly with this 60hz frequency.

It does this by “listening” to the frequency from the grid and matching its timing to it. If there is no grid frequency detected, the inverter will shut down. This is a code requirement because it would be dangerous for a solar home to send electricity into power lines that utility workers expect to be de-energized.

Adding batteries to your home solar system

If you want your home to remain powered during a grid blackout, you’ll need to add batteries to your system.

With batteries, your excess solar electricity will be first used to charge the batteries. Only when they’re full will your power go into the grid.

When a blackout happens, a battery-backed solar energy system will automatically use the stored electricity to power your home. If it’s still sunny, the solar panels will continue to generate electricity to power your home and charge the batteries. After the sun goes down, your home will be fully powered by the stored electricity until the battery runs out.

This means that you’ll need a large enough system to power your home through the evening until the sun comes up again. The average home uses around 30 kWh of electricity in a day.

One Tesla Powerwall battery will store 13.5 kWh of electricity, so two Powerwalls should be able to power the average home in sunny conditions, especially if the home curtails its normal electricity usage to help get through the blackout.

Is the cost of a battery system worth it?

The Powerwall costs about $6,500 each, or $0.48 per watt. In 2019, this is the most inexpensive lithium-ion solar battery on the market, but there are some competitors. If you’re lucky, you might be able to take advantage of discounts.

For most homeowners, the cost of a battery system isn’t worth it, especially if they have net metering. However, with PG&E planned blackouts becoming a regular part of life in California, the inconvenience of repeated power outages might make it worth it for some, especially if they have sick or elderly people at home.

Also, new PG&E solar customers are required to have a time-of-use (TOU) plan. This provides an added incentive to add batteries, because peak hour rates are between 3 pm and 8 pm on weekends. Solar energy generation starts to fall off during this period, which means using more expensive grid power. With batteries, you can use stored energy to get you through the peak period without using grid power at all.

How to prepare for a planned blackout with solar batteries

Fortunately, PG&E issues warnings ahead of planned blackouts. This gives a solar homeowner time to prepare.

Smart solar batteries, like the Tesla Powerwall, can be programmed from a smartphone to operate in different modes. For example, there is a backup-only mode that reserves 100% of the electricity for emergency use.

Tesla Powerwall

If you know that a planned blackout is coming, switch your Powerwall to backup-only mode. This will ensure that you have the maximum amount of power available to get you through the blackout.

Other smart lithium-ion batteries may have similiar functionality, but if you have lead acid batteries, you’re most likely not using them on a daily basis, but reserving them for backup power. Read our guide on solar batteries to learn more.

Financial incentives for solar batteries

The recent wildfires in California have made apparent the value of distributed energy resources such as home solar. By bypassing the need for long distance generation, not only does the grid become more resilient, but safer for everybody as well.

This is one reason why California is offering incentives for battery storage paired with self-generation (such as solar and wind). Read more about the SGIP program at the California Public Utility Commission website.

In addition, the federal tax credit of 30% (in 2019) applies to solar batteries as well. That takes a significant chunk out of the price of your system. Read more about solar rebates or use our solar pricing calculator to quickly estimate your costs.

Distributed solar is the future in California

With PG&E struggling under bankruptcy while facing billions of dollars worth of legacy infrastructure that needs to be upgraded to be made safer, it’s apparent that rolling blackouts are going to be the norm for the foreseeable future.

Along with the obvious clean energy benefits of solar, situations like this make it clear that the distributed nature of home solar is an another important benefit.

If you’re thinking of going solar, use the links below to quick check your costs or to get multiple quotes from qualified solar installers in your area.