External maintenance

External maintenance of your solar energy system should be performed twice a year. The entire outside surface of the collecting devices needs inspection and cleaning. Inspect the outside of all parts of the system. Remove, inspect, and clean the glazing, if the glazing is plastic it’ll need replacing every few years. While the glazing is off check the absorbing surfaces for rust, leaks, paint checking, or any other evidences of weakness or deterioration. Scrape, sand, repair and/or replace as needed, and repaint. Check the insulation, whatever kind, for any breach. Follow all lines through, checking for evidence of liquid, air, or heat leaks. If there’s a reflective surface, check it for focus. shine, and protective coating. You may contact Sydney solar for professional advice and solution.

During reassembly, use fresh sealer and caulk. Double-check the supporting framework. If you have a focusing system, check that the moving parts are free and lubricated; clean and repaint any checked or rusted spots. This is a good time to run tests on all of your safety circuits, using a continuity tester or a VOM for current, and resistance.

Open the union at the solar energy collector outlet if you’re using an auto thermostat for outlet temperature control. Remove it and place it in a pan of water, with a thermometer, to check its accuracy. If you’re using differential thermometers, check their circuitry, per manufacturer’s instructions. If you’re using a Heat/Vap method of collecting, drain out some fluid and measure its boiling temperature; it may become altered—diluted, or concentrated—during a year’s use. Check thermistors, wherever you’re using them; see the manufacturer’s material for testing procedures. Use a silicon lubricant on all solenoids as you reassemble them.

Internal Maintenance

Internal Maintenance is critical if you have a water-based solar system. (An air system check is complete when the above items are covered.) It’s necessary to empty and acid wash a water system periodically, depending on several factors. These include the operating temperature, the higher, the more frequently, the quality of the water, and chemicals used to maintain it. Each year take out a sample of the liquid and test it, better yet, have it tested at a commercial laboratory. It should be checked for copper ion concentration, and for iron ion, at the minimum; this is also a good time to have the raw water analyzed, to be sure you’re using the best possible additives. The year you see a significant jump in the copper or iron ion content, it should be acid washed. “Jump” means many things; in no case exceed 0.01% increase.

If your system has a drum for liquid storage, open and inspect it every six months. It should look clean; if you’re using the proper treatment, it will. If it doesn’t look clean, it must be acid washed, or hand cleaned, depending upon its size. If there’s a lot of scale, you’re using water of too high a hardness. You need a water softener or a de-ionizer, or possibly different chemicals. The proper amount and kinds of sequestering agents and buffering agents for pH will prevent the deposit of scale. The lines and tubes in the collecting and transfer systems are harder to inspect; they’re also the more likely areas to contain deposits. Even if the drum is clean the tubes should be acid washed when the copper or iron ion concentration jumps. If you’re using a solid material for the heat exchanger/storage vessel base, the tubes there may need acid-cleaning every two or two and a half years.

Acid Cleaning is a technical, dangerous job, proceed carefully; use professional help if you can get it. First, before anything else, mask the entire collecting system from all sunlight. Acid washing is done by circulating a weakly acid solution through the collecting, transfer, and heat exchanger and storage components. Commercially, a six or seven per cent Hydrochloric acid (6 to 7% HC1.) solution is circulated, at 1600 to 1700F, not over 1700F, for two hours. A professional acid cleaner would also add 1% Hydrofluoric (HF) acid, but do not use HF at home. It’s extremely dangerous to handle. (HF is the acid that will etch glass–and a drop will destroy an eye.)