Solar Hot Water (Solar Thermal)
Save Money With Free Hot Water from the Sun
Most homes in Maine, New Hampshire, and Massachusetts heat their water using high-mass oil boilers. All summer these boilers must stay on, sporadically firing to heat domestic hot water.
Solar hot water counters this situation by providing solar-heated water during the summer months, allowing you to:
- Shut down your home's boiler from May through October
- Save 100s of gallons of oil
- Have reliable hot water throughout your home
Not only do homes with solar hot water save money and C02 emissions, most customers report that showers with solar hot water just feel better!
Professional System Design and Installation
After 10 years installing and servicing solar hot water systems in the harsh climates of Maine and New Hampshire, we've distilled our knowledge into a design we believe to have the highest efficiency and longevity, with the lowest installation costs. Our designs are proven in the field with over 1,000 happy customers in Northern New England.
ReVision Energy's solar thermal systems are compatible with any existing water heating system, whether it's electric, gas, or oil-fired. During our free solar site evaluation one of our highly trained, experienced solar designers will visit your home and evaluate whether a solar energy investment makes sense for you.
Our systems featured a 'closed-loop' design, meaning that we use nontoxic antifreeze that never comes in contact with your drinking water to exchange heat. Our systems operate trouble-free throughout the winter, and are designed for automatic overheat protection so that you can leave the system unattended in summer without issues.
How Solar Hot Water Works
- Collectors on the roof (collect heat)
- Storage tank in basement (stores heat)
- Pipe run from basement to roof (moves heat down from roof)
- Pump station/sensors on tank (turns on pump when there is heat available on roof)
Non-toxic antifreeze is pumped from the basement to the collectors; after being heated by the sun the antifreeze is pumped back down to the basement and circulated through a heat exchange coil located in the bottom of the solar storage tank. As the antifreeze passes through the heat exchanger, is transfer the solar heat to your domestic hot water supply. When you run a shower, or wash your hands, the hot water from the solar storage tank flows up and into the tap in your house.
ReVision Energy builds automatic backup into all solar domestic hot water systems so that when the sun can't get the job done, you don't have to worry about cold showers. We can tie into an existing oil boiler with a dual-coil tank, preheat another water tank, or install a solar tank with an electric element for backup.
Am I a Good Candidate for Solar Hot Water?
Solar hot water makes the most sense for:
- Homes inefficiently heating water now (i.e. using an oil boiler or old electric tank)
- Primary homes or homes used year-round
- Homes with high hot water loads (families of 4+, apartments)
Use our interactive solar hot water calculator to see what kind of system might work for your home:
Solar Thermal Calculator
Your SHW System
Welcome to the Solar Calculator
This version of our solar calculator lets you size a solar hot water system to meet your home's needs. Systems are sized based on hot water need - a product of the number of a home's occupants and relative water use.
What Goes In a Solar Hot Water Job?
ReVision Energy borrows from leading European solar thermal system designs for robust, resilient systems designed to sustain decades of New England winters. Our solar hot water systems are a closed loop design, meaning that the fluid that passes through the solar hot water collectors never comes in contact with your drinking water supply (and thus can be winterized), and feature the industry-accepted best practice of steamback design for overheating.
There is much more in a solar hot water quote from ReVision Energy than the quotes by most other dealers. Here is a brief summary of the major components and how/why we select them.
Solar Hot Water Collectors
There are two major designs of solar hot water collectors - evacuated tube collectors and flat plate collectors. We are unbiased in our choice of collectors and choose the collector best matched for the application. Both designs are productive and efficient, but they offer unique characteristics that determine in which situations they are best suited.
Evacuated tube solar collectors tend to offer the best year-round performance, as they feature incredible vacuum insulation that prevents system heat losses in Maine's relatively cold climate. The cylindrical shape of the tubes enables them to better harvest low-angle wintertime sun at our northern latitude. They do not shed snow as well as flat plate collectors, but overall they are better winter performers which makes them a preferred choice for most residential installations.
Historically, flat plate solar hot water collectors have offered superior summer performance, making them a better choice for homes with higher summertime hot water loads. However, this is changing with our adoption of the incredible Wagner Euro C-20 flat plate collector. Wagner is known as a solar pioneer in Germany and started designing, producing, and improving collector design 32 years ago. The Wagner C20 collector is the most efficient flat plate collector that is available in the United States according to SRCC ratings.
Factors such as roof pitch, roof layout, expected hot water load (and seasonal demand), expected snow load, aesthetics and cost are all factors in determining whether evacuated tubes or flat plate solar hot water collectors are better for you.
The Solar Storage Tank
A purpose-built storage tank is critical to the success of a solar hot water system. It's critical that a solar storage tank be:
- Built out of rugged materials to perform well for the span of the system's life (20+ years)
- Well-insulated, with 2-3 inches of foam insulation to ensure minimal heat loss overnight from solar heated-water
- Properly sized for your household's needs; it should neither be too small, so that it stressed to keep up with demand, or too large, so that solar is never effective at provided a significant fraction of the home's domestic hot water needs
For installations with an oil boiler as backup, we choose Stiebel Eltron tanks as they manufacture the best dual coil solar storage tank on the market. Stiebel's purpose-built tanks are super-insulated with 3 inches of urethane foam to store precious BTUs harvested from the sun and its two internal heat exchange coils allow for easy integration with almost any boiler-based heating system. This porcelain-lined steel tank comes with a built-in sacrificial anode rod with a wear indicator that is easy to view and replace if necessary.
For systems requiring electric backup, we typically will install an 80 or 119 gallon Caleffi solar tank, and 2" of non-CFC rigid foam insulation which offer R16 insulating value.
The "brains" of the solar hot water system is the pump station. Ours feature a high-quality 3-speed circulator, check valve/ball valve, pressure relief valve, fill and drain ports, flow meter and sight glass, temperature gauge and pressure gauge. System operation is governed by a variable speed differential temperature solar controller that is able to harvest more solar energy than DC-based systems. Our smarter RESOL controllers will harvest more thermal energy than a solar-panel + pump system during low-light situations such as early in the morning and in overcast conditions.