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San Francisco to require rooftop solar on all new buildings

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PV Magazine

The new legislation requires solar PV systems, solar water heating systems or a combination of the two. San Francisco has set a goal to use 100% renewable energy by 2025 in addition to other ambitious environmental targets.

New commercial and residential buildings of up to 10 stories in San Francisco will have to install rooftop solar systems. Powertree Services/California Energy Commissi

New commercial and residential buildings of up to 10 stories in San Francisco will have to install rooftop solar systems.
Powertree Services/California Energy Commissi

San Francisco on Tuesday became California’s first major city to mandate solar installations on new buildings.

The move, which goes into effect in January, follows similar mandates passed by smaller municipalities Lancaster and Sebastopol in 2013, according to the San Francisco Examiner.

New commercial and residential buildings of up to 10 stories in height will have to install rooftop solar systems for heat or electricity under legislation that was unanimously approved by the city’s Board of Supervisors.

“In an era when we are reminded daily of our rapidly changing climate, it is so important that we continue our strong push to alternative, non-fossil fuel energies,” said Supervisor Scott Wiener, who introduced the legislation.

San Francisco has set a goal to use 100% renewable energy by 2025 in addition to other ambitious environmental targets.

The San Francisco Examiner quoted Barry Hooper, the Department of Environment Green Building Coordinator, who said last week that 100% renewable energy depended “on both development of renewable energy resources and continued improvement in energy efficiency.” He added that the ordinance represented another “straightforward and pragmatic step” toward that goal.

The legislation requires solar PV systems, solar water heating systems or a combination of the two.

California state law already requires most new buildings to have 15% of the rooftop “solar ready” in order to facilitate the installation of PV systems, the newspaper said.

The legislation adds to San Francisco’s environmental efforts, which also includes a new renewable energy program, known as CleanPowerSF, set to launch later this year.

Source: PV Magazine. Reproduced with permission.

  

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  • Brunel

    Does it mandate solar hot water?

    I think now it is better to get solar PV + heat pump instead.

    As the heat pump can be operated by a Powerwall at night.

    • solarguy

      A good solar water heater won’t need electricity at night or most days in fact, where a HP will use power every single day! A Powerwall will not do much for a HP at night anyway especially considering other loads it would need to run.
      Sorry, but back to the drawing board old chap.

      • Brunel

        The heat pump would be powered by solar PV during the day.

        If 4 people live in a house and they all have a shower before the sun comes up, the tank will run out of hot water.

        • solarguy

          Sorry mate still not thinking. If the tank could run out of hot water before dawn, then if your PV is of the right capacity for all day time loads, then run HP during the day, plus what you need for night time loads in storage. But look, HP’s are energy suckers, that can’t compete with a good SHW, simple, as they do for the most part produce hot water without electricity.

          • Brunel

            Will the tank keep the water hot for 12 hours – 6pm till 6am.

          • solarguy

            Well of course, providing there is water left over to keep hot. A lot of HP’s have only 180 Lt capacity, not much for 4 people.

          • Our house has solar hot water which is used every day, including showers and the occasional large bath and so far we have never run out of hot water. Obviously the system needs to be sized and insulated properly.

      • Doug Hendren MD

        If you have a cellar space that needs dehumidifying, it makes an HP water heater very sensible.

        • solarguy

          Ventilation would be a cheaper and more simple solution,now that would be more sensible.

          • Doug Hendren MD

            Yes, if the underside of my home were insulated. A few years back, after getting multiple opinions to do so from engineers and architects, I insulated the crawl space. It has made a big difference on heating bills and general comfort, but the 15×15 concrete floor of the utility room was enough to over-humidify the space. Ventilation would have defeated the purpose of insulating the crawl space. The heat pump water heater proved a reasonable solution. And it was 1/4 of the cost of installing solar hot water for 2 retired people. I couldn’t justify the $8k estimate.

          • solarguy

            I’m trying to visualize things here Doug. Firstly, what was the $8k estimate for?
            2) Is the utility room connected to the crawl space that is insulated?
            3) I can’t understand why you think ventilating the crawl space would defeat the purpose of insulation?
            4) Is the heat pump in the utility room?

          • Doug Hendren MD

            Two separate estimates came in at $8k for solar hot water. We live in rural Virginia, not a lot of suppliers. Our home is on a limestone ridge with a lot of radon exposure. When I tightened up the house, I thought it best to in some way prevent radon exposure via the crawl space. There is one utility room with cement floor, connected to the crawl space under the rest of the house. As you know, the cement floor is basically a 100% humidity condition, but it’s not intuitively obvious to most of us until we experience it. Rather than spray the whole underside of the house with closed cell foam, I elected to insulate the crawl space. That made the crawl space 55 degrees summer or winter (confirmed by remote temp. sensor) which made the house a lot more comfortable. I believe that ventilating the whole space would have reduced moisture in winter, but would not prevent condensation in summer (very humid here).
            My point was simply that the heat pump water heater also functions as a dehumidifier.

  • nakedChimp

    Way to go!

  • john

    At least some good policy in place not happening in other areas.
    Not going to happen when the regulations are in place that restrict PV to 5 Kw as is common in some places.
    It is pathetic that shopping centers have no PV on the roof let alone the car parking areas.