• Why You Don't Need A Solar Battery

    Watch the video above to learn about San Diego's new Time of Use Rate Structure for solar homeowners.

    We at SunPower by Stellar Solar have batteries, and we will sell you a battery, but you don't need one.  Here's why:

    A couple of weeks ago, a new rule went into effect with SDG&E where everyone who goes solar has to use a Time of Use rate structure.  The default rate structure that everyone goes on when they go solar is called DR-SES.  DR-SES only counts for five months out of the year, June through October, so in the seven months that are considered Winter, these rates are fairly flat.  What you're going to notice is that there are three rates during the course of the day: the super off-peak rates which are basically 23¢, off-peak (middle of the day) which is 28.5¢, and On-Peak which is 53.8¢.  
    A typical homes usage is such that there is a little power used in the morning, usage goes down during the day when everyone goes off to school and work, and then it peaks from 4-9PM when most people return home from work and are using appliances.  The utility understands these usage rates, which is why they are charging very expensive rates, (53.8¢ kWh) at these times.
    Your solar panels start to produce in the morning, they peak midday, then they go down in the afternoon.  They won't be producing as much power in the peak rate time (4PM - 9PM) so you will be barely offsetting the high-peak rate.  The strategy is to earn enough credits from your solar panels from when your panels are producing more than your house is using to offset the power being used at the high rate time.  
    Many companies are selling batteries to offset the high rate period.  Instead of that, you can opt for using TOU-DR rates instead of DR-SES.  TOU-DR is for the same 5 months, but the rates are much flatter.  The most important rate is the middle of the day solar credits at 27.1¢, while the middle of the day rate, which was very high in the TOU-DR structure, is now only at 32.9¢, so you need much less of the solar credits to offset that rate period.  The differential here is only 6¢ per Kilowatt Hour, while the differential in DR-SES is 28¢ per kilowatt hour.  
    So SunPower by Stellar Solar's strategy is that when we put a proposal together, we figure out your usage by looking at your electric bill, and then we add a couple of panels.  We then add one or two panels into the mix, which allows you to generate enough solar credits in the off-peak times at 27¢ to fully offset the amount of energy you'd be using at 33¢ a kilowatt.  
    The only caveat is that under TOU-DR, is that, if you look at your electric bill on page 3 under the electric section, it will tell you what your baseline allowance is.  You multiply the baseline allowance by 130%, and that's how you reach your cushion.  As long as you keep the difference between your home's usage and your solar production less than your cushion (typically around 400 kWh), then you're good to go with the TOU-DR rate structure.  
    For example:
    If your home uses 1,000 kWh a month
    You subtract 800 kWh 
    And end up with 200 kWh a month.  That is less than your 130% cushion, so you're good to go with the TOU-DR rates.  
    This strategy works much better, as you've purchased more solar panels instead of a battery to do what you need to do.  What you'll also notice is that a battery only has a 10-year warranty, and the inverter only has a 12 year warranty, so you're replacing a good portion of your system every 10-12 years where a better strategy is to go TOU-DR, add a couple of panels, and you've accomplished the same goal.  
    If you'd like to learn more about how this works, contact for a free solar quote today.  
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