San Francisco Department of the Environment

Solar Water Heating Consumer Guide

Today, San Franciscans are searching for more information about renewable energy options, and while solar electric has received a good deal of attention, solar water heating has been largely overlooked. Water heating accounts for more than 4% of San Francisco's total CO2 emissions. The majority of water heaters in the City are fueled by natural gas and typical household spends almost $1,000 a year on gas bills. With the federal tax credits and California solar water heating incentives available, solar water heating is becoming an increasingly attractive option. 

After personal vehicles, gas water heaters and furnaces are the biggest source of on-site greenhouse gas emissions in our homes, along with other harmful nose-level pollutants like carbon monoxide and particulates. Choosing to install a solar water heating system can help reduce pollution right in your neighborhood, while bringing your utility costs down, providing new green jobs, and ensuring a secure, local energy supply.

How Solar Water Heating Works

A solar water heating system is a simple and reliable energy source for your home. Generally, solar collectors are mounted on a south facing sloped or flat roof. Fluid (water or glycol) flows through the panel and is heated by the sun. It then runs to a solar storage tank connected to your existing water heater. Your water heater only turns on if the solar-heated water still needs a temperature boost. Hot water flows out of your taps just like it always has, but your water heating bill could be cut 60-80%. You will also reduce greenhouse gas and other air polluting emissions from your home! There are two basic types of rooftop solar collectors:

  • Flat-plate collectors contain a working fluid (water or a waterglycol mix) that flows through tubes in the collector, is heated directly by the sun, and carries that heat to the hot water storage tank. The dark glass covering and insulated backing are specially designed to collect heat and prevent it from being radiated back out of the collector.
  • Evacuated tube collectors have a set of long dark glass tubes with metal absorbers in their cores, which are heated by the sun. Cool working fluid flows past the top of the metal absorbers, is heated, and carries that heat to the hot water storage tank. The glass tubes are vacuum-sealed, making them very efficient heat collectors. The round tubes also help to capture solar energy even when the sun is lower in the sky.

Incentives Are Available!

The State of California and the federal government are offering financial incentives for solar water heating systems. Combined, they can decrease system cost by 50-75 percent! For a complete list of solar water heating incentives, click here.

Solar Water Heating Installers in SF

SF Environment recommends obtaining at least three bids from different solar installers prior to proceeding on your solar project. It's important to ensure that your solar contractor holds all appropriate licenses, certifications, and insurance policies for your project. For a list of solar water heating installers that serve San Francisco, click here.

Financing Your Solar Water Heating Project

Installing a solar water heating system on your property allows you to decrease your natural gas bills and reliance on fossil fuels. In addition to the economic and environmental benefits provided by solar energy, it can also increase your property value, decrease your carbon footprint, and help hedge against future utility rate increases. Click here for information on the various financing mechanisms available for solar.

Related Content

Residential Solar Water Heating Guide
Commercial Solar Water Heating Guide
Multi-Family Solar Water Heating Guide
NREL SWH Consumer Guide