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Home > Research > Photovoltaics > Virgin Islands Energy Office > Solar Hot Water Systems - St. Thomas

Stylized Text: VIEO: Solar Hot Water Systems - St. Thomas.

As part of the US Virgin Island Energy Office (http://www.vienergy.org/) solar water heating program, the following systems were installed on the island of St. Thomas in March and April 2002. The system were installed by West Indies Solar (http://www.westindiessolair.com/). Other specifics on the systems cane be acquired from the Site Listings web site.

1. Breunlin

The system installed at this site uses solar energy to power a direct current (dc) pump using a photovoltaic (PV) panel. The PV panel converts sunlight into electricity, which in turn drives the dc pump. In this way, water flows through the collector only when the sun is shining. The dc pump and PV panel are suitably matched to ensure proper system performance. The pump starts when there is sufficient solar radiation available to heat the solar collector. It shuts off later in the day when the available solar energy diminishes.

Picture of a solar thermal collector.

Once the collector and photovoltaic module was installed, the client constructed an aluminum structure enclosing the collector. During hurricanes, the client will detach the photovoltaic module, place it in the site built enclosure and close the enclosure. (Note that the yellow rope shown in the picture below was used by the installer during the inspection - it is not part of the system.)

Picture of a solar thermal collector.

2. Williams

This site uses what is referred to as an Integral Collector Storage (ICS) System. In the integral collector storage solar system , the hot water storage system is the collector. Cold water flows progressively through the collector where it is heated by the sun. Hot water is drawn from the top, which is the hottest, and replacement water flows into the bottom. This system is simple because pumps and controllers are not required. On demand, cold water from the house flows into the collector and hot water from the collector flows to a standard hot water auxiliary tank within the house. Due to logistics of the two story residence, it was decided that a ground mount was the most feasible installation option.

Picture of solar thermal collector on a mountain top.

3. VIEO Sun Power Display

Two solar water heating systems are displayed at this site.

In the integral collector storage solar system , the hot water storage system is the collector. Cold water flows progressively through the collector where it is heated by the sun. Hot water is drawn from the top, which is the hottest, and replacement water flows into the bottom. This system is simple because pumps and controllers are not required. On demand, cold water from the house flows into the collector and hot water from the collector flows to a standard hot water auxiliary tank within the house.

The other is a thermosiphon system. As the sun shines on the collector, the water inside the collector flow-tubes is heated. As it heats, this water expands slightly and becomes lighter than the cold water in the solar storage tank mounted above the collector. Gravity then pulls heavier, cold water down from the tank and into the collector inlet. The cold water pushes the heated water through the collector outlet and into the top of the tank, thus heating the water in the tank. A thermosiphon system requires neither pump nor controller. (Because of this, the thermosiphon and ICS systems are often referred to as passive system.) Cold water from the city water line flows directly to the tank on the roof. Solar heated water flows from the rooftop tank to the auxiliary tank installed at ground level whenever water is used within the residence.

Picture of a solar thermal collector.

4. Hachette

This site also uses what is referred to as an Integral Collector Storage (ICS) System. In the integral collector storage solar system , the hot water storage system is the collector. Cold water flows progressively through the collector where it is heated by the sun. Hot water is drawn from the top, which is the hottest, and replacement water flows into the bottom. This system is simple because pumps and controllers are not required. On demand, cold water from the house flows into the collector and hot water from the collector flows to a standard hot water auxiliary tank within the house.

This system was not mounted on the roof, the traditional location for solar collectors, but instead adjacent to the sough facing wall of the residence.

Picture of solar thermal collector and several installers.