Solar Hot Water heating
What is Solar Hot Water (SHW)?
Who hasn’t returned to their locked car on a summer day to find the interior scorching hot? Solar domestic hot water (SHW) systems use the same “greenhouse effect” to heat water for use in homes and businesses.
An SHW system works in tandem with your existing water heater. This means you get hot water from the solar system when the sun is shining, and never need to worry about not having hot water when it's not.
How does it work?
Open or Closed-loop SHW systems trap the sun’s energy inside an array of box-like collectors or glass tubes to heat a freeze-resistant, food-grade propylene glycol liquid in a series of copper tubes or heat pipes. A pump circulates the potable water in an oen loop system or heated glycol in a closed loop system from the collector to the water tank where it passes into the cylinder with open loop or through a coil for glycol systems and transfers its heat to replenish the hot water supply.
SHW collectors are weather proof, heavily insulated and designed to absorb the maximum amount of available heat. Tempered solar glass allows solar radiation to enter but prevents approximately 95 percent of the heat from escaping. A specially treated copper absorber plate is placed next to the copper tubing to transfer even more of the sun’s radiated energy to the heat transfer fluid. Then the liquid glycol in the copper tubing circulates through a heat exchanger coil inside a well-insulated holding tank, not unlike the tank used in your conventional water heater.
The heated wwater or glycol transfers its heat to the water in the tank before returning to the collector where it’s heated again and the cycle repeats.
- Solar energy arrives at the collector mounted on the roof
- The heated water or glycol arrives to heat the hot water cylinder, this is pumped by the controller on the hot water cylinder
- Solar hot water is used in the house supply and backed up mostly by electricity.
How does it save money?
SHW uses energy from the sun to offset the cost of the natural gas, propane, heating oil or conventional electricity normally used to heat your water. Over the year a SHW system can provide as much as 60%-75% of all water heating needs. During the summer months the system operates at its maximum usually 100% with little extra heating from conventional sources required.
What is the payback time?
About 40 percent of the average family's energy use comes from the cost of operating a domestic water heater. The savings garnered from an SHW system, and the corresponding increase in home resale value, will usually pay the cost of installation within 6-8 years, the fastest payback of any renewable energy system. And, over the next 40+ years of its life expectancy, your SHW system is actually putting money back in your pocket!