Solar Hot Water - Flat-Plate Collector Facts Solar Hot Water - Flat-Plate Collector Facts

Flat plate collectors are the most common means of harnessing the sun’s energy to power a solar hot water heater. Depending on the circulation system employed, flat plate collectors work well both in cold and warm climates, making them the most adaptable alternative for solar hot water heaters.

Solar Hot Water Alternatives

When you decide to install a solar hot water heater to replace your traditional model, you have several choices to make. The first is whether to install an active or a passive system—that is, one with powered pumps or one without. Next, you must choose a circulation system. Direct circulation systems move the home’s potable water directly through the solar collector to absorb the heat while indirect systems move a heat transfer liquid through and transfer the heat to the potable water in the storage tank. Lastly, you have to decide which type of solar collector you want. As stated, flat plate collectors are the most universally adaptable. If, however, you live in a warmer climate, an integral collector storage or “batch” system is possible. Flat plate collection systems have costs and benefits, so before you decide, it helps to understand the facts.

Flat Plate Collector Facts

ICS or “batch” systems are less expensive that flat plate solar collectors. They typically have fewer parts and require less maintenance, but they are less efficient and unsuitable in cold weather climates. Flat plate collectors, on the other hand, involve a series of copper pipe, either S-shaped or in parallel that run through the collector box. The components are contained within an insulated metal box with a translucent cover or glazing over the front. The plate itself is made of copper or aluminum and is painted with a dark coating to increase solar absorption.

Flat Plate Direct Systems

This type of circulation system pumps the potable water directly into the solar collector to absorb the heat energy from the sun. As the dark metal plate absorbs the sunlight, it speeds up the molecules in the water, thereby heating it and then pumps it back out and into the storage tank for use. This type of system is suitable in warm climates where freezing rarely occurs. Due to the serpentine shape of the pipes within the collector, water is prone to collect there and freeze if temperatures drop. A direct drain back system using a flat plate collector is possible in colder climates. Water, once heated automatically drains back into the storage tank, leaving nothing to freeze.

Flat Plate Indirect Systems

An indirect system pumps a heat transfer liquid through the flat plate collector. Rather than circulate the potable water directly, a different liquid is heated in the plate and pumped into the tank where a heat exchanger transfers the heat energy to the potable water. The heat transfer liquid can be water (for drain back systems), hydrocarbon oil or a refrigerant of some kind.

Flat plate solar collectors usually involve more cost because of their somewhat complicated makeup. Their conception is fairly easy to understand, but after all of the parts are taken into account, they are quite involved. Flat plate collectors are, however, the most common form of solar collection device, so if you are considering installing a solar hot water heater, the facts are necessary to make an informed choice.

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