Types of Solar Hot Water Systems

Domestic Hot Water

The heart of a solar hot water system is the solar collector. These devices transfer the sun's energy into a fluid (usually water or a glycol mixture). There are several types of collectors, each having their own advantages and disadvantages. The fluid that is heated in the collector flows into a storage tank. In a glycol system (a.k.a. closed system) the heat is transferred to the potable water through a heat exchanger. In a water system (a.k.a. open system), the water typically goes directly into the potable system. An open system is typically designed to 'drain-back' the water that is in the collector when the temperature falls to prevent freezing. These systems are less expensive; however, they are typically used in warmer climates or only in seasonal applications in the Berkshires.

Solar Space Heating

There are two different classifications of solar space heating, passive and active. Passive heating can be as simple as having many windows on the south facing side of a home. These can be augmented by careful selection of building materials that have a large thermal storage mass. These materials act as heat 'banks' which store the energy during the day and then release it during the evening.

Active systems have the ability to generate even more heat. The heart of a system is the solar collector. These devices transfer the suns energy into a fluid (usually water or a glycol mixture, but sometimes even air is used). There are several types of collectors, each having their own advantages and disadvantages. The fluid that is heated in the collector is pumped into the home and into radiant heating units or it is pumped into large storage tanks for use later in the day when heating is needed. These systems can be integrated to produce domestic hot water or other specialized heating needs. Often this type of system works well with radiant floor heating.

Pool Heating

Pool heating systems work much the same way an active space heating system works (link to 'active systems). There are large solar collectors that capture the suns energy and transfer it to a fluid, in this case the pool water. These systems are very simple in that they often use the existing pool circulator pump to push the water through the collectors. They also have simpler collector designs that consist of a myriad of tiny black tubes. These systems can't be run in very cold weather, as they typically are not equipped with freeze protection. These systems can also be put in series with a conventional pool heater to act as 'economizers'. This arrangement allows for assured heating regardless of weather and season. A solar pool cover ("bubble pack") is still often used in either application as it serves to insulated the pool and reduces the heat losses at night.