How much hot water do you use, and what do you use to heat it?

A solar water heater will heat up to 70% of your home's hot water. The payback of a solar water heater varies based on what you are currently using to heat your water and how much hot water you use every day.

16% of the average Massachusetts home’s annual energy use comes from water heating alone—two-thirds as much energy as used for all electronics, appliances, and lighting! As a result, the amount of money you can save depends on how much hot water you use on a daily basis and what fuel you use to heat it.

A solar water heater will provide 50-70% of the average home’s hot water needs, replacing fuel that would otherwise be consumed in a conventional water heater. If you live in one of the 40% of homes in Massachusetts that use electricity, fuel oil, or propane to heat water, you’ll be able to save a lot of money on your energy bill from installing solar water heaters.

The average family of four can expect the following energy savings from installing a solar water heater:

Solar Water Heater Expected Savings*

Fuel Type Oil Electricity Propane Natural Gas
Fuel Cost $3.13/gallon $0.157/kWh $3.35/gallon $1.38/therm
Annual Savings $360 $830 $570 $75
Lifetime Savings $7,200 $16,600 $11,350 $1,500
Years to Payback 9.6 6.1 6.8 16.1

Your actual savings are likely to be different from the table above. In general, if you use more hot water than the average family, you will save more money with a solar water heater.

Don’t forget: energy prices are constantly fluctuating. While gas, oil, and electricity prices go up and down, sunlight is always free. The water heated by a solar water heater is virtually cost-free, with low maintenance costs over the system’s 20-30 year lifetime. As a result, solar water heating is a great way to lock in energy prices today and avoid the price swings associated with fossil fuels.

*Annual savings are average expected savings over 20-year lifetime. Assumptions for expected savings include: fuel prices of $3.13/gallon for oil, $3.09/gallon for propane (Massachusetts winter 2014/15 average, MA DOER), 15.72 cents/kWh for electricity, and $1.38/therm for gas (Massachusetts averages from 2011-2014, EIA) and escalators ranging from 0.8% to 2.1% EIA Annual Energy Outlook 2015, Reference Case for New England); solar fraction of 70%; three collectors installed at $12,000 (average from MassCEC Commonwealth Solar Hot Water Rebate database); and use of all available incentives, including a 0% interest Mass Save Heat Loan (see here for more information on SHW incentives).