|
Passive and Active
With solar, hot water can be produced in a number of different ways and systems are generally categorized as either passive or active, direct or indirect. Passive systems are those that rely on natural convection to circulate water through the system while active systems employ the use of pumps and valves to circulate their liquid.
Direct and Indirect
All systems regardless of whether they are active or passive are always further categorized as direct or indirect. Direct systems commonly known as “open loop” systems are those Systems that heat potable water (fit for bathing and drinking) and deliver that water directly to the faucet or appliance. Indirect or “closed loop” systems use a non-freezing liquid instead of potable water which is circulated through a coil in a storage tank or heat exchanger to heat the potable water for use.
Components to Solar Hot Water Systems
Most solar hot water systems consist of either Flat plate collectors or Evacuated gas tubes to capture the sun's energy. That heat energy is then transferred directly or indirectly to potable water and delivered for immediate use or held for later use in storage tanks.
These storage tanks may sometimes have a backup heating element in them (like a conventional hot water heater). This is called a “one-tank” system. Another common system uses a separate tank that has no element that feeds into the tank of a conventional hot water heater. This is called a “two–tank” system.
Whether or not one or two tanks are used, the solar energy captured by the collectors preheats the home's water and can produce water up to 140°F on sunny days. At night and on cloudy days, the conventional heater acts as a booster heater to bring the stored water up to household temperature otherwise it remains off and is not used saving you form spending huge amounts of money on oil, electric or natural gas
|
