Battery Backup Vs. Generator for Solar Array
Updated: Oct 20
Nearly 1 million customers of California’s largest electrical utility were left without power this month following an intentional grid shut down by Pacific Gas & Electric. This shutdown came in response to heavy winds and dry weather conditions to prevent wildfires from starting. With most of central California left without power, attention has been drawn from around the country. As lines begin to pile up at fuel stations for those running gas powered generators, some homeowners experienced little to no change during the blackout, running their homes off of solar power with battery. If you were affected by the outage or are taking preventive measures for future power outages, read on to learn the benefits of a solar-powered battery backup system compared to a diesel generator below.
Battery vs. Generator | Which is best for me?
Comparing generators to batteries is a case of apples and oranges. To make the right decision, first establish what your energy goals are. Both applications will be a considerable investment, so if price and payback is your top priority, a battery might be your best option. “ROI” is a common word in renewable energy, and rightfully so. It is a common misconception that there is no ROI on a battery. I disagree. Your battery can be configured so that it is used daily, unlike a diesel generator that only runs during a grid failure. What this means, is that you have the ability to take electricity from your battery every day before taking electricity from the grid.
I like to think of a battery as an “external hard drive” that is always ready to go and keep you backed up. When the grid is up and running, it acts as “cloud storage” providing you power when you have maxed out your “hard drive”. However, using a battery on a daily basis comes at a risk. If your battery is configured to the maximum DOD (Depth of Discharge), you run the risk of the battery dying and the grid failing overnight. If there is no solar attached to the battery or no sunlight during the outage, the battery may not be able to recharge itself. If ROI is not your primary goal, then configuring a battery to remain at 100% and only work in the event of an outage is your best option.
A traditional generator has it’s advantages too. It will run day or night, sunny or cloudy. As long as you have the ability to refuel, you don’t have to worry about running out of power during an outage. If ROI is your primary goal, then this is not the option for you. The only time you will ever generate a return is during a grid failure. A power outage is like all bad things in life; it feels like it lasts a lot longer than it actually does. In the United States, there is an average of 2.5 grid failures per month averaging less than 48 hours (Inside Energy). It isn’t until we have no power that we realize truly how much our day-to-day life depends on it. But realistically, it is not that much time. That means you only will get a return on a diesel generator an average of 2 days out of the year. With prices within the same range, the scale leans heavily towards installing a battery in nearly all categories.
Do I need solar to have a battery?
Solar energy is not required to install a battery at your home. The key difference is that you cannot “refuel” a battery without sunlight during a grid failure like you can refuel a diesel generator (assuming you have access to fuel). A battery can be charged from grid power, but you are always at the mercy of your utility pricing by going this route. With solar, you can charge and recharge, maintenance-free. There is a common misconception that solar only works in the sunny “hotspots” in the United States. As you can see in the image to the side, there are still enough quality sun hours a day to provide anyone in the United States with enough energy to fully charge a battery.
LG CHEM Resu 10H
This lithium-ion battery is our first choice for a home energy storage solution because it can be paired with a solar panel system. When paired with a SolarEdge inverter and optimizers, users can track their power consumption, solar production, and battery levels at any time of the day. This battery requires a critical panel load to be installed, with a simultaneous 25A capacity. For the typical American home, this would still allow you to power the essentials to get by during an outage (refrigerator, bathroom, furnace, etc.).
Generac 20kW 6244
This whole house generator has an air-cooled aluminum enclosure along with technology that allows it to safely and efficiently power any household item. A 200A auto transfer switch provides you with the ability to power an entire home, as opposed to only critical loads as a battery would.
To conclude, I believe that the future is bright for solar with energy storage. With costs continuing to decline it is becoming more and more affordable for homeowners to transition to a renewable option. With competitive pricing and no sounds or smells, solar with battery is my unanimous winner.