Solar Water Heating System Maintenance

[Abstract]

Solar energy systems require periodic inspections and routine maintenance to keep them operating efficiently. Also, from time to time, components may need repair or replacement. You should also take steps to prevent scaling, corrosion, and freezing.

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

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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.

• 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.

• Support structures

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

• Heat transfer fluids

Antifreeze solutions in liquid (hydronic) solar heating collectors need to be replaced periodically. 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

Avoid Water Scaling

Domestic water that is high in mineral content (or "hard water") may cause the buildup or scaling of mineral (calcium) deposits in hydronic solar heating systems. Scale buildup reduces system performance in a number of ways. If your system uses water as the heat-transfer fluid, scaling can occur in the collector, distribution piping, and heat exchanger. In systems that use other types of heat-transfer fluids (such as glycol, an anti-freeze), scaling can occur on the surface of the heat exchanger that transfers heat from the solar collector to the domestic water. Scaling may also cause valve and pump failures on the potable water loop.

You can avoid scaling by using water softeners or by circulating a mild acidic solution (such as vinegar) through the collector or domestic hot water loop every 3–5 years, or as necessary depending on water conditions.

Freeze Protection

Solar water heating systems, which use liquids as heat-transfer fluids, need protection from freezing in climates where temperatures fall below zero degrees C

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.

【Conclusion】

It is easy to detect most of the common solar water heater problems on your own. Regular inspection, freezing protection etc can be controlled at home, but serious maintenance work like replacements should be done by a technician. To be safe, always have a certified solar technician inspect the system regularly ensure that everything is working well.