• When homeowners in San Diego County start doing their solar research, a common question they have is: What is the average sized solar system in their area?  This is a complex question, as the average size of a solar installation in any given community is based on a number of factors including: median home value in that area, distance from the coast, density of homes in the area, etc. Despite the complexity of this question, we wanted to attempt to address it. But instead of looking at San Diego in general, we looked at 20 of the top solar municipalities in San Diego County, and, by tapping into our database of over 10,000 installations, we calculated the average system size (in kW not number of panels) for each of the communities. We also looked at how average home values and distance from the coast correlated with system sizes, to see how influential those factors were. 

    What determines the size of a solar system?

    Before we begin, we have to define the term “size” when it comes to solar systems. When we talk about the “size” of a solar system, we are not speaking about literal physical size - we are talking about electrical rating or output in kilowatts; however, sometimes a higher output system will also be physically bigger. But since modern panels produce more kW per panel than older ones, a physically smaller system (in square feet or  number of panels) can now create the same amount of electricity (in kW) as older systems that simply take up more space. So just because a solar system is physically “bigger”, doesn’t mean it has a larger electrical rating in output.

    Our Methodology

    Our methodology for this study was simple: we took our database of thousands of installations throughout Southern California and sorted them by the number of installations we have completed in that area. We then calculated the average of all the installations in the area.We also used data from Zillow on the average value of homes in each of these areas, and sorted them by that number.

    So, as a disclaimer, this data is based on our own customer data, not data from all solar installers in the area. For this reason,  the data may not be completely universal.

    Our Assumptions

    Many critics of solar energy say that solar panels, due to their cost, are only a good solution for wealthy homeowners. If these critics are correct, you would expect that the higher the home value, the larger the solar energy system. However, we've sold a lot of solar to all areas of San Diego County and to all demographic groups. What we ourselves would expect (based on our experience) is that the farther the community is from the coast, the higher the electric bill and therefore, the larger the system size. Let’s take a look at the data to see if it backs up those assumptions.

    Our Findings

    Our findings somewhat surprised us and defied some of our expectations - but when you look at the different factors at play, mostly make sense. We ordered the cities in ascending order by home values, to get an idea of any correlations that exist in size as home values go up.

  • CityMedian Home Value ($)Size in kWMiles from Coast
    El Cajon5124007.5822.2
    Escondido5172006.919.3
    Santee5195005.721
    Ramona5256008.2527.8
    Oceanside5327006.020
    Chula Vista5383006.047
    Vista5405006.988.7
    La Mesa5706006.5414
    Fallbrook5789008.319.5
    San Marcos5900006.9512.5
    City of San Diego6341006.19
    Jamul67720010.0630
    Poway7423008.4317
    Carlsbad852006.690
    Encinitas10795006.910
    Solana Beach13744006.810
    La Jolla16112007.90
    Coronado17833006.330
    Del Mar24844007.210
    Rancho Santa Fe248610014.295.8
  • The average system size in San Diego County is 7.49kW, or 23.4 panels. The range is large between municipalities like Santee and Rancho Santa Fe, but you can see that most cities have an average of around 6 - 8.5 kW and 20-25 panels. 

  • So as you can see, there isn’t a very strong correlation between system size and median home value, that is until you get to the $2,000,000+ range, where both the system size in kW and home value spike. There is a little bit of a correlation when it comes to inland cities like Poway and Jamul that lie in the $600,000 - $700,000 range but other than that, system sizes are mostly consistent, between 6 and 8.5kW. You can see with high value real estate cities like La Jolla and Coronado, that are close to the ocean, that home values do not really correlate with bigger systems.

    Average System Size in kW vs. Distance from Coast

    The other assumption we had going into this study was that distance from coast and system size would correlate. Let’s take a look to see if that assumption was correct. 

  • So, as you can see, there does appear to be a correlation between distance from coast and system size, especially as home values go up. In Poway and Jamul, which both are in the medium-high range of average home value, and are also over 15 miles from the coast, you see the strongest correlation. You can also see the correlation in the Ramona and Santee areas although they are on the lower end of average home value. The only oddity here is the spike at 5.8 miles, but that is because that distance represents Rancho Santa Fe, which has the highest home values of all the municipalities.

    Takeaways

    Clearly, very large homes have big energy footprints no matter where they are located (La Jolla or Rancho Santa Fe) and very large homes usually cost more. However, because land is cheaper further from the coast, such as in Jamul, people tend to build larger homes there and also have added land to build larger ground-mounted systems. It makes sense then that, as we saw from the data, that system sizes spike in areas where the home values are higher, as well as being further from the coast. There isn’t much of a correlation with just home values because homes near the coast that aren’t as large and don’t use as much energy as the inland large homes may be just as or more expensive than those large homes with big energy demands. The point being that solar can work for everyone, but is especially beneficial to those with larger homes that live inland.

    What should be noted as well is that these are averages, and the range of system sizes within each of the municipalities is relatively wide. Just because there is an “average” system size for any given municipality, these averages should not serve as an indicator as to what your system on your home will be - as every home is different and there is a wide range of home sizes in every municipality. To know for sure what your system size will be, you need an energy consultant to work up a quote for you. If you’re interested in what size system you will need for your home - contact us today and one of our energy consultants will reach out.

     

  • About the Author

    Michael Powers

    http://www.terrawatts.com/

    Michael is one of the founding partners of SunPower by 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 is a certified practitioner and coach for TED* (*The Empowerment Dynamic). 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.