Profile: A Solar Hot Water System in Wayland

DSCF9749_500This is Kaat again. Our solar PV system came online in 2011 (you can read more about that here). We had purposely left the shadiest part of our roof for solar hot water (SHW). That system was put on in 2013, when our  old water storage tank (plugged into our oil-furnace) broke.

We knew we wanted to heat our water with the sun, and we knew that the room we had left on our roof would not have sufficed to add extra PV and then an electrical method of heating our water. Solar thermal Hot Water it was then.

But our first problem was that there were too many estimates and too many configurations. Knowledge is power, and we sure did learn a lot, and met some wonderful people, but it was quite a time investment. Lucky for you, selecting a good Installer is already done by Solarize LSWNew England Solar Hot Water (NESHW for short).

Back Up system

Figuring out what to use as backup was a big factor. We had reserved the shadiest part of the roof for the SHW because those collectors are a lot more forgiving of shade than PV panels. For comparison, our solar fraction on the sunnier, PV part was 81% on average, that more eastern location was 73.1%. “Solar fraction” means that SHW there will provide that portion of your hot water on an annual basis, calculated on the average hot water usage in New England.

But how then to heat the other 26.9%?

We looked into electrical backup alternatives, which involved an (electrical) heat pump, a second, electrical water tank, possibly on-demand, etc. We didn’t, however, have enough room on our roof for additional PV panels to cover that extra electrical load. Also, we heat our home with oil (no gas on our street) and had recently invested in a super-efficient oil furnace.

You can see that it gets complicated… Lucky for you, figuring out what sort of system the particular home calls for, will be done by SolarFlair and New England Solar Hot Water. They will work together to advise you on the efficiency, financial and environmental implications of the choices for your home.

In the end we went with the most straightforward system, which was to run two heat exchangers through a super-efficient new hot water tank: one to the solar heat collectors on the roof, and one to our super-efficient oil furnace, which became the back-up heater for when this happens:


Remember that winter?

Our system (2013)

The system (collectors, plumbing and the new water storage tank with its two heat exchangers) was installed in February 2013. The installation process was much quicker (it only took them seven hours), and there was no wait for the utilities to turn it on.

Since then, our oil furnace doesn’t come on, at all, for the four warmest months in the year. During those months, the SHW system supplies enough hot water for five people.


The system comes with a sensor system, which generates a monthly report. The latest one (August 2017) reported we have generated:

28,559,617 BTUs
2,863 lbs Coal
3,550 lbs CO2
4,598 miles Driven

Costs (in 2013!)

  • $8000 – $2000 (State rebate: 25% of the cost up to $3500) – $1800 (30% Federal tax credit) = $4200.
  • Because we’re frugal users of hot water it’ll take an estimated 14 years for the system to have paid for itself (shorter, obviously, if oil prices or if our consumption go up).

Costs have come down and incentives have gone up since then!

Exclusively for our Solarize program, New England Solar Hot Water offers:

  • a two-collector, 80 gallon storage tank systems for approx. $2,183
  • a three-collector, 80 gallon storage tank systems for approx. $2,389
  • (these numbers are for typical situations. Yours may vary.)


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