No Power? No Problem.

How to achieve energy independence at home (or at least freedom from PSPS)

In 1962, the physicist and philosopher Thomas Kuhn coined the term “paradigm shift” in his landmark book The Structure of Scientific Revolutions. Originally used to contrast emerging, breakthrough scientific ideas with their incumbent counterparts, the term has grown to become synonymous with disruptive technologies that threaten the status quo. The recent Public Safety Power Shutoffs (PSPS) that have plagued Sonoma Valley are symptomatic of a vulnerable and aged energy infrastructure, whereas advanced technologies such as solar, home battery backup, and controllable smart breaker panels hint at the opportunity for a consumer-driven paradigm shift.

The Evolution from Solar Power to Energy Storage Systems

Conventional solar-energy systems provide a financial benefit to home-owners by generating clean, renewable energy during the day that is traded with the utility for a profit. With massive price declines and strong financing options, residential solar has been installed on more than 10 percent of California households. But looming changes to Northern California power conglomerate PG&E will shift the solar-value-proposition to include the need for energy storage. By adding a battery to their solar systems, homeowners gain two critical features. The first is the capability to store energy produced by a solar system to trade with the utility at ideal time periods—often later in the day when solar production is diminished but the value of energy remains high. The second key feature of a battery is more obvious—the ability to provide reliable backup power to a home during a grid outage.

Basic Battery Types and Chemistry

Home battery systems come in multiple shapes and sizes and can range widely in the features available via the battery management system used. Most stationary home batteries utilize lithium-ion cells, the same chemistry found in phones, laptops, and electric vehicles. Lithium-ion batteries tend to be more cost-effective with longer lifespans than traditional lead-acid batteries (the type that starts your car). Within the lithium-ion battery family, the two most prevalent options are lithium NMC and lithium-iron-phosphate (LFP). NMC batteries are more cost effective, and LFP batteries are safer. All commercially available home batteries are subjected to vigorous standards and certified by Underwriter Laboratories.

Determining Ideal Size and Backup Capability

Energy use within the home varies widely among customers, with the primary drivers being square footage, number and type of appliances, and day-to-day usage patterns. Similar to generators, batteries are rated by the amount of continuous power they can provide at any given instant (measured in watts). Smaller batteries provide around 5,000 watts, whereas a medium-sized unit can provide around 8,000 watts. In addition to a continuous power level, battery ratings are also gauged by their energy storage capacity, measured in kilowatt-hours. Higher wattage equals more power available, whereas more kilowatt hours equals a longer backup duration. Determining the right battery for your application can be achieved by taking an inventory of which “dedicated loads” would be powered during a grid outage, estimating the amount of usage of each load throughout the day, and summarizing this into a table. The easiest method for doing this is to contact a solar and battery backup professional, who can prepare a spreadsheet to review different usage scenarios and select the right size battery for your application.

Connecting the Battery With Your Home Electrical System

Unlike standby generators, a home battery system can work in parallel with the grid when it’s operational and revert to backup power when the grid fails. To achieve this, the battery is hard-wired into your electrical service panel through a dedicated load sub-panel, a select set of circuit breakers that become isolated in an outage event. The benefit to this approach is that these loads are isolated and powered during a blackout. The drawback is that homeowners are required to pre-select which loads are protected during an outage, which can be a challenge.

A new class of breakers known as “smart breakers” offers to solve this dilemma. Smart breakers operate much like a traditional circuit breaker, but can be operated remotely via a relay. By using smart breakers, homeowners can elect to back up all circuits in their home and choose which circuits to power in an outage based on their available energy storage. Advanced smart breakers come with control software and user interfaces that allow homeowners to select devices intelligently from any browser, iPad, or even their mobile phone.

Upfront Costs, Financing Options, and Return on Investment

Depending on the battery size chosen, combined solar/battery installations can range from around $20,000 to upward of $35,000 gross, before eligible tax credits and cash incentives from PG&E. If installed in 2020, both the battery and solar panels are eligible for a 26 percent federal tax credit. After all subsidies, the net cost of a solar/battery system can fall below $12,000, which is directly comparable to the cost of an installed stationary generator. But unlike a stationary gas generator, batteries can be financed through the Property Assessed Clean Energy (PACE) program from Sonoma County, which offers financing periods of 10 and 20 years. The PACE program is not a loan; instead it acts as a tax-assessment on the property, which can loan up to 10 percent of the appraised value of the home. For most homeowners, the monthly financing cost of a solar and battery system is comparable to, or lower than, their existing PG&E bill and not subject to escalation.

These financial assumptions are based on a continuously evolving financial and political landscape as governments and energy companies respond with subsidies and pricing incentives to consumer demand and improving technology for renewable energy systems.

If there is one immediate benefit to the catastrophic wildfires raging across California the past three years—and the subsequent precautionary power outages that have followed—it is the urgent incentive to reduce vulnerability to public safety power shutoffs while simultaneously reducing the threat of fires spawned by the inherently unsafe infrastructure of the massive power grid.

As is so often the case in human history, it sometimes takes a fire to inspire the creation of a hose. 

Story by Andrew Krause