Mandatory solar for new construction – housing killer or PV boom?


St. Petersburg, Fla., became the latest city to propose requiring solar photovoltaic systems on new residential construction and not yet fully defined extensive remodeling and additions. It would join South Miami in implementing mandatory solar where major building permits are sought.   

Actions like these have long-term policy implications as cities move to incorporate renewable energy and other sustainability standards. But what kind of a tangible impact will requiring solar on new construction and extensive remodeling have on St Petersburg housing stock? If history is any guide, it won’t be dramatic.

According to 2014 statistics, St. Petersburg issued 177 building permits for single family new construction, about 0.1% of the 129,401 housing units in the Florida city. New construction rates in built up cities like St Petersburg are considerably lower than in more rapidly growing areas.

The numbers could be higher for existing building permits that would require solar installations. According to 2016 U.S. Census housing data, 17,752 building permits were issued for the Tampa-St Petersburg-Clearwater metropolitan area. As an estimate, if one pro-rated the 129,000 St Petersburg housing units by the 1.39 million units in the metro area, that would be about 1,600 building permits in the city.

The 1,600 or fewer building permits in a year represent about a 1% annual impact on the housing stock. But the number of retrofit and remodeling permits that would require solar installations is probably lower than that if they don’t involve roof work or additions. Furthermore, there could be limitations to how much solar could actually be installed, due to shading from other buildings or aesthetic complaints from neighbors.

This modest output has been indicated in one of the first cities (2014) to require mandatory solar on new residential construction, Lancaster, Calif. Like St. Petersburg, Lancaster has similar housing statistics. Using, Lancaster’s population is about 160,000, somewhat larger than St Petersburg. The California city’s average cost of new construction housing of $278,000 is a couple of thousand less than the Florida city. New construction, however, is about 100 units a year in Lancaster, considerably less than St. Petersburg, and nearly all have had solar installed on them.

As cooling needs in terms of degree days, if not humidity, are similar between the two cities, St. Petersburg would require about an 8 kW (AC) system to accommodate a state average 13,692 kWh per year of electric consumption. A price tag of $20,000 to $25,000 before incentives would be a significant cost factor to absorb, on the order of adding a new bathroom or bedroom.

The theme is that mandating solar energy systems on new construction is neither a housing market killer nor the be-all end-all for addressing clean power or environmental issues. Properly done, it can address supplying solar power to a specific market that mainstreams PV. Except for high growth areas, potential impact rates for mandatory localities appear to be around 1% or less per year of potential single family housing stock.

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