Solar Water Heater

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Green Real Estate, marin county homes, money savings ideas, solar water heaters, sustainable living

Technology Snapshot & Benefits:

Solar water heating systems utilize the sun’s energy to heat water for use within a household or commercial property. Typically, solar water heaters are made up of a storage tank, a solar collector, and a series of tubes, valves, pumps and fluids that allow for water circulation. While certain systems may function at higher capacities in warmer locations with greater sun exposure, they do work in all climates. Different models are available for the home, pools, and commercial properties.

There are two types of solar water heating systems – active and passive. The former have circulating heat pumps while the latter do not. Active systems are either direct (circulates water directly from collectors to the home) or indirect (circulates non-freezing heat transfer liquid from the collector through tubes in the storage tanks to heat the surrounding water). Passive systems, which are generally cheaper, but less efficient, are typically either integral-collector systems or thermosyphon systems. Integral-collector systems are best in warmer climates where temperatures rarely drop below 32 degrees. Thermosyphon systems use basic water principles for circulation by placing the outlet that goes to the home at the top and the outlet that goes to the solar collector at the bottom. This allows for the hot water (which rises) to go to the home and the cold water (which sinks) to be circulated through the solar heater.

Storage tanks should be well-insulated to prevent heat loss. There are two main types of storage tanks: two-tank systems and one-tank systems. Two-tank systems have an additional conventional water heater attached for back-up while one-tank systems have the conventional heater and solar heater integrated into the same tank. Both systems provide back-ups in case the solar heat is insufficient on any given day.

There are many different types of solar collectors and system set-ups. Consult a local specialist and the online resources listed at the bottom of this page to determine which type is right for you.

For a basic overview of the different types, visit http://www.fsec.ucf.edu/en/consumer/solar_hot_water/homes/system_types.htm,.

Estimated Cost Savings:

While solar water heating systems are more expensive than conventional heating systems, they can save you up to 50-80% on your water heating bills. The amount of money you save depends on several factors, including the amount of water, geographic location, fuel costs, financing incentives available, and the system’s performance. Installation and maintenance costs create additional expenses, but these are still minimal when compared to overall savings.

To determine your estimated savings, visit http://www.energysavers.gov/your_home/water_heating/index.cfm/mytopic=12910.

For information on financial incentives in your state, visit the Database of State Incentives for Renewables and Efficiency (http://www.dsireusa.org/).

Issues: As solar heating systems rely on the sun’s energy to heat your household’s water, weather can sometimes create an issue by preventing adequate sunlight from reaching the collector. However, the storage tanks often store enough hot water to compensate for lapses in sunlight. Also, a conventional water heater is attached to most systems to provide back-up in case there is not enough solar heat.

These systems require a decent amount of maintenance to ensure they are working properly. Check annually for problems like obstructions shading the collector, failing pipe and storage tank insulation, and visual signs of wear or corrosion on pipes and tanks. Consult a technician for routine qualified inspections. For a complete list of recommended inspections, visit http://www.energysavers.gov/your_home/water_heating/index.cfm/mytopic=12950.

Regional Issues:

It is important to take into account local temperatures when choosing a solar water heater. While the heaters generally work for any climate, certain types will not work in colder climates where temperatures frequently drop below freezing because the outdoor components may freeze. Dry climates may also require extra maintenance including cleaning the collector glazing as there is no natural rainwater to cleanse it.

As solar water heaters use the sun as a source of energy, items blocking direct sunlight may inhibit their proper function. Be sure to trim branches and trees that may block sunlight.

Check local codes and regulations before installing a solar water heater. Some areas require permits or special permissions before installation. See the U.S. Department of Energy’s Building Codes, Covenants, and Regulations for Solar Water Heating Systems for more information and to find the requirements in your area (http://www.energysavers.gov/your_home/water_heating/index.cfm/mytopic=12920).

Installation (Getting It Done):

Most solar water heaters require professional installation. For a list of solar water heater companies,visit http://www.fsec.ucf.edu/en/consumer/solar_hot_water/homes/installation/index.htm. If you decide to install your system yourself, visit Florida Solar Energy Center for a series of articles to help guide you through the process (http://www.fsec.ucf.edu/en/consumer/solar_hot_water/homes/installation/index.htm).

Before installing a solar water heater, make sure there is enough sunlight to create noticeable energy savings. In the northern hemisphere, this typically means installing the solar collector on a south-facing roof. In some cases, they can be installed on roofs facing up to 90 degrees east or west and still provide adequate heat. Consult a professional to find out what type of solar water heater best suits your needs before purchasing. Also, remove any obstructions that could potentially block sunlight from reaching the collector. These include branches, satellites, tall trees, etc. Collectors should usually be installed flat on the roof or according to the guidance of your installation professional.

As a rule of thumb, solar collectors should be at least 20 square feet for each of the first two family members in the house. For any additional family members, add 8 square feet if you live in the Sunbelt region (south and southwest U.S.) and 12-14 square feet if you live in more northern regions. For example, if you live in the Sunbelt region and there are five people in your house, your solar collector should be at least 64 square feet (20 + 20 + 8 + 8 + 8) to ensure adequate hot water supplies.

The size of the storage tank also correlates to the number of people in the house.

Small – 1-2 people

Medium – 3-4 people

Large – 4-6 people

It is important to purchase the right size solar collector and storage tank for your system to properly heat enough water for every member of the household.