Solar hot water panels need to face South but can tolerate a little shading. 40 degrees is the optimum angle for yearly production. They should be mounted on the roof or close to the building. If on the roof, there needs to be a way to get 2 insulated pipes from the basement up to the roof.

How They Work
Solar Hot Water Systems take advantage of the fact that the Sun provides 1000 watts of energy on every square meter of the temperate zones of Earth at midday. Solar water heaters collect and store some of this energy. The most common kind of collector is called a "flat plate" collector. Basically an insulated black box with glass on top of it, the collectors have tubing that a water/antifreeze mix is pumped through. The heat gained by the liquid is then transferred to a solar storage tank by means of a heat exchanger. In the summer, this tank can provide all the hot water you need. In the winter, it can serve as a preheat to your regular hot water heater.

Larger solar hot water systems can also be used to make heat for houses. More collectors and storage is needed and ways to use or dump the excess heat in the summer need to be considered.

A Number of Reasons to Do Solar Hot Water

• Supplementing hot water heating with solar panels is a very effective way to help the Environment and save money as well, particularly when used year-round.
• A solar hot water system can provide all the hot water you need in the summer and, serve as a preheat to your hot water supply in the winter. On a clear, blue sky January day, the water in your solar hot water tank may get as hot as 100 degrees. It then goes to your regular water heater where it is boosted up to 120 degrees for your use. Since water comes out of your well at about 50 degrees, this is a significant fuel savings even in the wintertime.
• Solar Hot Water reduces dependence on our island’s imported fuels and provides a hedge against rising fuel costs.
• When supplementing an electric hot water heater that is used year-round, there is less than a 10 year payback.
• 2 solar hot water panels will reduces carbon dioxide emissions by about
  7100 lbs./year if supplementing electric water heating,
  3100 lbs/year if propane, 3760 lbs/year if oil.

Costs
A 2 panel solar hot water system costs approximately $5000-8000 installed depending on how complex it is to connect to your existing hot water heater. If new, certified components are used, the system may be eligible for both the State and Federal tax-credits.

Simpler summer systems are less expensive.

System Considerations
Solar hot water systems can overheat, and need to be designed according to your needs.

If you are interested in a system just for summer months, you might choose a batch heater or thermosiphon system. These systems are cheaper, but need to be drained at the end of the season.

For a year-round system, a closed loop design is best. The liquid in the system is either a non-toxic antifreeze/water mix or water. Temperature sensors at the collectors and at the solar tank regulate when the solar pump needs to run.

• Closed loop antifreeze systems have extra freeze protection, but overheating and stagnation can be issues if the water is not used on a daily basis.

• Drainback systems with either antifreeze or water tend to be simpler. In drain-back systems, the piping is continuously sloped so that the liquid drains back to the solar tank. When the pump shuts off, all the water drains out of the collectors. This is particularly important if your use of hot water is more intermittent.

Energy Efficiency is the most cost-effective way to reduce your contribution to Climate Change. Once this is done, installing solar at your house is a good, next step.

How to Get Started

The first step is to have your site checked to be sure it has good solar access- either on the building or, on the ground close to the building so that you don’t lose the heat you have generated to the ground. If the system is on the building, a route needs to be found that allows you to bring 2 insulated pipes, about 2” in diameter, from the roof down to the basement or wherever your solar tank might be located.

Fill out the Site Survey and send it back with the deposit, to have your site evaluated by Under the Sun, OR contact one of the solar hot water installers to evaluate your site.

A system then needs to be designed for you and equipment ordered by the solar hot water contractor.  A licensed plumber is required to do the necessary plumbing to connect to the building's hot water system.

Paperwork:
Permit application and inspection by Town Plumbing Inspector may be required.