California to add 650 MW of residential solar over 4 yrs thanks to new rule

California’s move to require new homes in the state to have solar panels from 2020 will have a positive net impact on residential solar installations of nearly 650 MW from 2020 through 2023.

GTM Research lifted its base-case forecasts for the California residential solar market by 14% for the four-year period after the solar mandate was approved on May 9.

Between 2020 and 2023, new residential buildings will add over 900 MW of solar capacity. Some of that had been included in GTM’s earlier forecast, because even without the mandate a certain percentage of California homes go solar from the start.

Multi-family housing units, many of which will also have to have solar panels under the new rule, are not included in the forecast. GTM puts these in the non-residential category.

Currently the average residential solar system size in the state stands at 6.8 kW. GTM’s calculations assume a size of 3 kW for new-build residential solar because they are more efficient. According to the California Energy Commission (CEC), 74,154 new single-family homes would be built in 2020, which could translate into the addition of 222 MW of solar capacity at a size of 3 kW per home for that year.

GTM assumes a flat 2% escalator of new residential housing beginning from 2020-2023.

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