Reliability is a core mission of electric utilities. Utilities are typically so effective at providing reliable service that customers are accustomed to having power available whenever they want it. As might be expected, when power is unavailable, customers become impatient, particularly when the outage lasts for several days. Many are considering backup power options.

An example of this is the recent experience in Northern California. Over a three-week period, residents experienced three extreme wind events accompanied by three, multi-day, public safety power shutoffs. Major sections of Northern California lost power for several days starting October 8, 2019. Nearly a million customers lost power less than three weeks later on October 26. Another half-a-million customers lost power three days later on October 29.

This loss of power sent people scrambling to adapt to the power outages. Some people stayed with friends. Others started eating in the dark and barbecuing their food outside. Others pretended like they were camping. And some with financial resources went to the hardware store to purchase a backup generator.

Coming out of the recent blackouts, we can now see the value in building customer resiliency. I recently wrote a blog about how distributed solar + storage could be combined with emergency load reduction to result in a more resilient electric grid. But how could utilities help prepare their customers for a loss of power in other ways? Is there a role for the utility to help build customer resiliency?

While the criticality of the utility to modern life is not in question, utilities can greatly reduce their customer power outage shock by building customer resiliency, or—put another way—encourage self-reliance. I see this this as a two-pronged strategy:

  1. educate customers on minimizing energy usage; and
  2. promote solutions that serve as a temporary source of emergency power.

Utilities as educators: good energy decisions in a crisis

The first part of the strategy is to educate consumers on minimizing energy usage during an outage. This can be accomplished by helping customers understand how to prioritize consumption based on the value of power and the cost of meeting that power. The cost of power is approximately linearly related to the amount of energy consumed. That is, the cost scales with the amount of energy produced. The same thing, however, is not true with the value of power. The initial fraction of energy consumption will provide the largest percentage of value.

For example, suppose the average residential Pacific Gas and Electric (PG&E) customer consumes 6,500 kWh per year. This translates to 18 kWh per day. While every home is different, consumption is allocated to uses such as lighting, refrigeration, charging electronic devices, base loads, HVAC, heating air circulation, cooking, dishwashing and laundry.

Suppose if during a blackout, a consumer decides they would get half of the value of a typical day’s power if they had just enough energy to power a refrigerator, basic lights and a few electronic devices:

  • Refrigerator: A typical residential refrigerator that is less than 10 years would use around 500 kWh per year or 1.4 kWh per day.
  • Lights: Five LED lights that have a 7-Watt power rating and are operated 6 hours a day translates to 0.2 kWh per day (i.e., 0.007 kW per light * 5 lights * 6 hours per day).
  • Electronics: Finally, assume that two phones and a laptop computer use 0.2 kWh per day.

This home would consume less than 2 kWh per day. This is a reduction of 90% over typical operating conditions. In this situation, the initial fraction of energy consumed is the most valuable because it’s powering critical/key functions.

The second part of the strategy is to promote the adoption of solutions that serve as a temporary source of backup power.

Solar + storage: great solution, not applicable to all

An obvious solution that advances self-reliance is to install solar + storage. In this scenario, solar power is combined with a dedicated battery designed to meet the consumer’s needs during outage conditions. Such a system would provide outage protection under a variety of different situations when power from the grid is unavailable.

This solution is attractive in a variety of ways:

  • most or all loads could be backed up,
  • backup power comes on automatically, and
  • this solution provides long-term protection.

In addition to being costly, this approach may not be feasible for people that rent a home or live in multi-family housing (e.g., apartments or condominiums). At the time of this writing, Tesla, for example, states that one Powerwall costs more than $10,000 before incentives.

An alternative solution is for utilities to encourage the adoption of an electric vehicle (EV). Not only does EV adoption make sense for all of the traditional reasons (e.g., less pollution vs. a combustion engine), but an EV can also be a source of short-term self-reliance during an acute power outage.

Using an EV and inverter to provide backup power for select loads

When there are only a few small loads, consumers could use their car battery to run critical loads in their homes. Some people demonstrated that this is feasible with a traditional internal combustion engine (ICE) car in the recent power outages. One drawback of this approach is that vehicles must be left idling for long periods of time, not to mention the obvious contribution to lower air quality.

Alternatively, the idea of using a car battery as an energy source is particularly attractive when the car is an EV rather than an ICE vehicle. While full vehicle-to-grid (V2G) capability is not yet available in the U.S., some consumers have demonstrated how to meet critical loads.

One can attach a 12V DC-to-110V AC inverter to the car’s 12V battery. When properly configured and operated, the 12V battery will power specific loads and the main traction battery will replenish the 12V auxiliary battery as the charge is depleted. One blogger has a video of an actual implementation of this approach. One could refer to this as the vehicle-to-home (V2H) approach.

This is not just a hypothetical concept. In a recent inverter product review found on a popular e-commerce site, one California customer stated:

“Our electricity is down due to California winds…By attaching an inverter to the 12V battery, turning on the [EV]…and running extension cords into the house, I’ve powered key functions for 20 hours. It’s only drained energy from the [EV] at the rate of a mile for each hour of house use, which means in theory that I could keep my minimum functions going for over 200 hours.”

The disadvantages of this approach are:

  • only key loads are backed up,
  • it is not automated,
  • people need to be educated to safely take such an approach, and
  • it only provides as much power resilience as there is energy in the EV.

The big advantage is cost. A search for “dc to ac inverter for car” on an e-commerce website will show that the cost of this approach could be less than a few hundred dollars. Note that inverters capable of powering refrigerators will be more costly because refrigerators have a high initial power draw for a second or two as their compressors start.

Clean Power Research can help utilities educate their customers using a service called WattPlan®. WattPlan enables energy customers to make the best solar power and EV choices based on multiple variables. WattPlan can be configured for a variety of scenarios, such as allowing customers to evaluate the costs and benefits of a solar + storage system, an EV purchase, or both solar + storage and EV options.


Utilities provide highly reliable service. They are not, however, perfect. It is in the utility’s best interest to have customers that are prepared to have some level of backup power in the case of an outage. EVs represent a particularly interesting and cost-effective way to provide this backup. This is yet another way utilities can benefit from increased EV adoption.