How they work is not that complicated:

• A solar collector — the device through which pool water is circulated to be heated by the sun
• A filter — removes debris before water is pumped through the collector
• A pump — circulates water through the filter and collector and back to the pool
• A flow control valve — automatic or manual device that diverts pool water through the solar collector.

Talk to a contractor and see what they can offer.

Source: Department of Energy

Solar water heating systems use both direct and diffuse solar radiation. Ideally, if you live in a sunny, dry, and warm climate, it’ll be great to install one. However, northern climate might still have enough solar resources. The most important is where your home is built. If it’s built in a heavily wooded area, then it’ll not work.

The best way for you to find out if not through guessing, but consulting a solar system supplier or installer. They’re trained professionals who can conduct a solar site analysis.

Source: EERE

How does a solar water heater work? Solar water heating systems come with storage tanks and solar collectors. The storage tank is well-insulated and has an additional outlet and inlet connected to/from the solar collector. In a 2 tank system, the heater preheats water before it enters the conventional water heater. In 1 tank system, the backup heater and the solar storage are in one tank. The cost of a solar water heater usually is around $1,100.

Don’t rely on a collector’s and the piping’s (collector loop’s) insulation to keep them from freezing. The main purpose of the insulation is to reduce heat loss and increase performance. For protecting the collector and piping from damage due to freezing temperatures, you basically have two options:

• Use an antifreeze solution as the heat-transfer fluid.
• Drain the collector(s) and piping (collector loop), either manually or automatically, when there’s a chance the temperature might drop below the liquid’s freezing point.

Source: EERE, US Department of Energy

You might be able to handle some of the inspections and maintenance tasks on your own, but others may require a qualified technician.

For help finding a qualified technician, see the Learn More resources listed on the right side of this page (or below if you’ve printed out this page). Ask for a cost estimate in writing before having any work done. For some systems, it may be more cost effective to replace, shut off, or remove the solar system than to have it repaired.

Periodic Inspection List

Here are some suggested inspections of solar system components. Also read your owner’s manual for a suggested maintenance schedule.

• Collector shading

  Visually check for shading of the collectors during the day (mid-morning, noon, and mid-afternoon) on an annual basis. Shading can greatly affect the performance of solar collectors. Vegetation growth over time or new construction on your house or your neighbor’s property may produce shading that wasn’t there when the collectors were installed.

• Collector soiling

  Dusty or soiled collectors will perform poorly. Periodic cleaning may be necessary in dry, dusty climates.

• Collector glazing and seals

  Look for cracks in the collector glazing, and check to see if seals are in good condition. Plastic glazing, if excessively yellowed, may need to be replaced.

• Plumbing, ductwork, and wiring connections

  Look for fluid leaks at pipe connections. Check duct connections and seals. Ducts should be sealed with a mastic compound. All wiring connections should be tight.

• Piping, duct, and wiring insulation

  Look for damage or degradation of insulation covering pipes, ducts, and wiring.

• Roof penetrations

  Flashing and sealant around roof penetrations should be in good condition.

• Support structures

  Check all nuts and bolts attaching the collectors to any support structures for tightness.

• Pressure relief valve (on liquid solar heating collectors)

  Make sure the valve is not stuck open or closed.

• Dampers (in solar air heating systems)

  If possible, make sure the dampers open and close properly.

• Pumps or blowers

  Verify that distribution pumps or blowers (fans) are operating. Listen to see if they come on when the sun is shining on the collectors after mid-morning. If you can’t hear a pump or blower operating, then either the controller has malfunctioned or the pump or blower has.

• Heat transfer fluids

  Antifreeze solutions in liquid (hydronic) solar heating collectors need to be replaced periodically. It’s a task best left to a qualified technician. If water with a high mineral content (i.e., hard water) is circulated in the collectors, mineral buildup in the piping may need to be removed by adding a de-scaling or mild acidic solution to the water every few years.

• Storage systems

  Check storage tanks, etc., for cracks, leaks, rust, or other signs of corrosion.

Source: EERE, U.S. Department of Energy

How much money you save depends on the following:

* The amount of hot water you use
* Your system’s performance
* Your geographic location and solar resource
* Available financing and incentives
* The cost of conventional fuels (natural gas, oil, and electricity)
* The cost of the fuel you use for your backup water heating system, if you have one.

On average, if you install a solar water heater, your water heating bills should drop 50%–80%. Also, because the sun is free, you’re protected from future fuel shortages and price hikes.

If you’re building a new home or refinancing, the economics are even more attractive. Including the price of a solar water heater in a new 30-year mortgage usually amounts to between $13 and $20 per month. The federal income tax deduction for mortgage interest attributable to the solar system reduces that by about $3–$5 per month. So if your fuel savings are more than $15 per month, the solar investment is profitable immediately. On a monthly basis, you’re saving more than you’re paying.

Source: EERE, U.S. Department of Energy

* Does your company have experience installing and maintaining solar water heating systems?
Choose a company that has experience installing the type of system you want and servicing the applications you select.

* How many years of experience does your company have with solar heating installation and maintenance?
The more experience the better. Request a list of past customers who can provide references.

* Is your company licensed or certified?
Having a valid plumber’s and/or solar contractor’s license is required in some states. Contact your city and county for more information. Confirm licensing with your state’s contractor licensing board. The licensing board can also tell you about any complaints against state-licensed contractors.

Source: EERE, U.S. Department of Energy

After installation, properly maintaining your system will keep it running smoothly. Passive systems don’t require much maintenance. For active systems, discuss the maintenance requirements with your system provider, and consult the system’s owner’s manual. Plumbing and other conventional water heating components require the same maintenance as conventional systems. Glazing may need to be cleaned in dry climates where rainwater doesn’t provide a natural rinse.

Regular maintenance on simple systems can be as infrequent as every 3–5 years, preferably by a solar contractor. Systems with electrical components usually require a replacement part after or two after 10 years.

Source: EERE, U.S. Department of Energy

* Consider the economics of a solar water heating system
* Evaluate your site’s solar resource
* Determine the correct system size
* Determine the system’s energy efficiency
* Estimate and compare system costs
* Investigate local codes, covenants, and regulations.

Source: EERE, U.S. Department of Energy

Pumps circulate household water through the collectors and into the home. They work well in climates where it rarely freezes.

* Indirect circulation systems

Pumps circulate a non-freezing, heat-transfer fluid through the collectors and a heat exchanger. This heats the water that then flows into the home. They are popular in climates prone to freezing temperatures.

Illustration of an active, closed loop solar water heater. A large, flat panel called a flat plate collector is connected to a tank called a solar storage/backup water heater by two pipes. One of these pipes is runs through a cylindrical pump into the bottom of the tank, where it becomes a coil called a double-wall heat exchanger. This coil runs up through the tank and out again to the flat plate collector. Antifreeze fluid runs only through this collector loop. Two pipes run out the top of the water heater tank; one is a cold water supply into the tank, and the other sends hot water to the house.

Passive solar water heating systems are typically less expensive than active systems, but they’re usually not as efficient. However, passive systems can be more reliable and may last longer. There are two basic types of passive systems:

* Integral collector-storage passive systems

These work best in areas where temperatures rarely fall below freezing. They also work well in households with significant daytime and evening hot-water needs.

* Thermosyphon systems

Water flows through the system when warm water rises as cooler water sinks. The collector must be installed below the storage tank so that warm water will rise into the tank. These systems are reliable, but contractors must pay careful attention to the roof design because of the heavy storage tank. They are usually more expensive than integral collector-storage passive systems.

Illustration of a passive, batch solar water heater. Cold water enters a pipe and can either enter a solar storage/backup water heater tank or the batch collector, depending on which bypass valve is opened. If the valve to the batch collector is open, a vertical pipe (which also has a spigot drain valve for cold climates) carries the water up into the batch collector. The batch collector is a large box holding a tank and covered with a glaze that faces the sun. Water is heated in this tank, and another pipe takes the heated water from the batch collector into the solar storage/backup water heater, where it is then carried to the house.

Solar water heating systems almost always require a backup system for cloudy days and times of increased demand. Conventional storage water heaters usually provide backup and may already be part of the solar system package. A backup system may also be part of the solar collector, such as rooftop tanks with thermosyphon systems. Since an integral-collector storage system already stores hot water in addition to collecting solar heat, it may be packaged with a demand (tankless or instantaneous) water heater for backup.

Source: EERE, U.S. Department of Energy