• It was a hot summer in San Diego. In the first few weeks of September 2020, San Diego had a few days of record breaking heat, which meant that a lot of San Diegans were blasting their A/C. As a result of this power demand, SDG&E issued flex alerts, which encouraged San Diegans to keep their thermostats higher and to conserve energy however else they could in order to relieve the immense stress on the grid that was occurring during these hot times. Fortunately, San Diegans heeded the call, and as a result there were minimal outages.

    The events of this Summer have shown that the stability of our electric grid, which many of us San Diegans take for granted, is clearly not as solid as we assume. Many residents are likely wondering how this could happen and what the solution may be. One answer now being suggested in many local news publications is for more homeowners in the area to install solar + battery storage; this can reduce the amount of demand on the grid in times of high heat and thereby stabilize the grid.

    In this way, every homeowner in San Diego can be part of the solution to grid stability. By installing solar panels and adding battery storage, homeowners can use the sun to power their home during the day and store extra power in their battery for use during the evening hours, when peak demand for power is at an all-time high. In effect, every home with battery storage becomes its own self-sustaining power plant, and during times of strain on the grid, the home will be able to power itself and not put more load on the grid. 

    Let’s look more closely at how this works so we can better understand how a home with solar + battery storage can power itself and thereby reduce strain on the grid.

    How Installing Solar + Battery Storage Relieves Strain on the Grid

    The very simple idea behind installing solar + battery storage to lessen strain on the grid is that the solar panels allow homeowners to meet all of their power needs (plus fill up the battery) from 10am-4pm (or so); then from 4pm-9pm, when the solar production starts to "sunset," the home relies on the battery for power (instead of the grid). Most of the flex alerts take place from 12 noon to 9pm when grid demand is the highest, so solar + battery lowers this demand.

  • The graph above provides a visual example of how home solar production and battery charging can be utilized to offset usage.

    The purple curve represents the home's usage, or how much it is pulling from the grid. You can see first that in the 12:00am to 6:00am time slot, usage is obviously low, as most people are asleep. Then, in the 6:00am to 4:00pm slot, you can see that usage actually goes down as the Sun rises and provides enough power to offset the current usage, charge the battery (yellow) and earn extra solar credits for use at night, all at once. 

    In the 4:00pm to 9:00pm slot, you can see that, as usage goes up and solar production goes down, the power that was stored in the battery earlier is discharged and used during the peak power times. This not only saves the homeowner money by using the cheap solar power instead of the expensive On-peak power from the grid, it makes it so they are not pulling from the grid, and therefore putting more stress on it. 

    Real Life Example of Solar + Battery Use

    Let’s take a look at a real life example of how solar and battery storage work together to relieve stress on the grid. The graph below is from the solar monitoring of Stellar Solar Co-Founder Michael Powers’ home solar system. Here is a direct explanation from Michael of how his system works:

  • “At midnight on Sept 1st, the battery recharged (light green) so the state of charge was back to 100% (purple line). During the day, there is not much activity on the battery side because the solar is powering the house and selling back to SDGE.  But at 16:00 (4pm), you can see the consumption (blue) is met by the battery discharging that much (red). This continues from 4pm to 9pm and then the battery shuts off (although I could program it to continue discharging until midnight or whenever).

    The net result (see below) is that on that Sept. 1, I was selling power back to SDGE during the day (below the line) and then from 4pm to 9pm, my net purchases from SDGE (above the line) were zero. After 9pm, the battery stopped discharging and so my SDGE purchases came back:”

  • In this chart above, you can see that on September 1, Michael’s usage of power from the grid was limited to 9:00pm to 9:00am in the morning. That means that he was pulling power only when most households were starting to use less, so it not only decreases his home’s demand but shifts it until later, after the peak. So not only does Michael save money by not using power in the On-peak, more expensive time period, but he also is making it so he doesn’t pull power from the grid in that time. It’s a win-win situation for both the individual homeowner and the community.

    Solar and Battery Incentives

    Luckily for homeowners considering solar + battery storage, there are government incentives out there that make them more affordable now than ever. These incentives combined with the fact that electricity rates will only continue to go up, and we are undoubtedly going to have more fires and blackouts in the future, and there has never been a better time to install solar + battery storage than now. Let’s take a look at these incentives to see how homeowners can take advantage of the best deal possible.

    The Federal Solar Tax Credit

    The main government incentive for installing solar is the Solar Investment Tax Credit, a federal tax credit will pay for 26% of your solar installation. The Federal Solar Tax Credit has been around for many years, but started phasing out last year from its original level at 30%. It phased out by 4% to 26% this year, and will phase out another 4% next year to 22%, until it will completely go away for residential installations starting in 2022. It will remain at 10% for commercial installations indefinitely. 

    So if you’re looking to install solar, the next two years are the last that you will be able to receive a substantial tax credit. Considering that the average solar installation is around $20,000, that means that you could save around $5,000 if you go solar this year. With numbers like that, it’s no wonder the Solar ITC has been extremely successful promoting solar deployment nationwide since its inception.

    Self Generation Incentive Program

    The Self Generation Incentive Program (SGIP) is the main incentive for installing battery storage in the United States. Started by the California Public Utility Commission (CPUC), the SGIP program provides financial incentives to support the implementation of distributed energy storage systems. Technologies that qualify for SGIP incentives include wind  pressure reduction turbines, microturbines, waste heat to power technologies, internal combustion engines, gas turbines, fuel cells, and battery storage systems.

    In SDG&E territory, thousands of homeowners have already taken advantage of the SGIP program. $1,316,400 in incentives have already been distributed in the territory, and much, much more is already allocated. Incentive rates change based on how much of the funds are allocated, but as they stand right now, homeowners can get up to $0.25/Wh for installing small residential energy storage. That amounts to a few thousand dollars homeowners can save if they take advantage of the SGIP incentives.

    If you’re a homeowner in San Diego and you haven’t considered installing solar + battery storage, you can now see that there are benefits to both yourself and your community that are undeniable. The savings on Time of Use rates, the incentives, the solar savings themselves, and the benefit to the grid are all really good reasons to consider installing solar + battery storage this year, in 2020 in particular. If you’d like to get a quote on installing solar + battery storage, contact us today and we will put you in touch with one of our energy consultants.

  • About the Author

    Michael Powers


    Michael is one of the founding partners of Stellar Solar. In 2001, he helped launch The Home Depot’s national solar energy program which is now offering home solar through hundreds of stores in nearly a dozen states. He is a writer and marketing professional with over 30 years’ experience in the fields of energy, market intelligence and leadership training. He currently serves as treasurer and board member of Global Energy Network Institute (GENI), a San Diego-based non-governmental organization that advocates linking renewable energy resources around the world using electricity transmission.