Solar water heater care in Malta

Two kinds of system

Many Maltese roofs have a solar water heater as well as, or instead of, photovoltaic panels. They look similar from the street but do a different job: they heat water directly, rather than making electricity. Most are one of two types:

• Flat-plate collectors: a flat, glass-covered panel, often with a tank mounted above or beside it on the roof.
• Evacuated tube collectors: a row of glass tubes on a frame, usually feeding a tank.

Knowing which you have helps when cleaning, because tubes are cleaned one by one and can be fragile.

Why the glass matters

The collector works by letting sunlight through the glass to heat what is inside. Anything that blocks the light reduces how much heat it collects. On a Maltese roof, that means:

• dust from months without summer rain,
• Saharan dust and red rain, which leave a muddy film. See red rain and Saharan dust,
• salt near the coast. See protecting your home from sea salt,
• bird droppings, which also stain and etch glass if left. See bird droppings on solar panels.

Roof safety first

Solar water heaters often sit on the highest part of the roof, sometimes on the washroom roof or a raised stand next to the water tanks. Before you go near one:

• only go up if the roof has safe access and a solid parapet,
• never stand on the collector, the tubes, the tank or its frame,
• keep away from unprotected edges,
• do not go up alone, and avoid wet or windy days.

If it is only reachable by ladder or from the washroom roof, leave it to a professional.

How to clean the collector

1. Pick a cool time. Early morning or late afternoon. The glass on a working collector gets very hot in the sun.
2. Brush off loose dust with a soft brush on a pole.
3. Soak droppings with water before brushing gently. Never scrape.
4. Wash with water and a soft brush, top to bottom. Use purified water if you can. Malta’s tap water leaves mineral spots as it dries.
5. Tubes: clean each one gently along its length. They are glass and can crack.
6. No pressure washers, abrasive pads or harsh chemicals. Check the manufacturer’s instructions for anything else.

What to look for while you are there

A clean is a good chance to spot problems:

• cracked glass or broken tubes,
• drips or wet patches under fittings, pipes or the tank,
• rust or white corrosion on the frame, brackets and pipe fittings, especially near the sea,
• damaged pipe insulation, which sun and birds pick at,
• loose brackets or a frame that moves in the wind,
• nests under the tank or frame.

Do not try to repair any of these yourself. Take photos and call a plumber or the installer.

Hard water and scale

Malta’s hard water can build up scale inside water heating systems over time, as it does in kettles and electric water heaters. How a system should be descaled or serviced depends on its design, so this is a job for a plumber or the installer, following the manufacturer’s instructions. Do not flush chemicals through the system yourself.

When to call a plumber or installer

Call a professional if you notice:

• less hot water than usual on sunny days,
• water dripping from a valve or the tank,
• leaks, damp patches on the ceiling below or water on the roof that should not be there,
• noises, steam or unusual pressure readings,
• cracked glass, broken tubes or damaged pipework.

We clean the collector glass and tubes. We do not service or repair the plumbing, tank or valves.

Alongside your solar panels

If you also have photovoltaic panels, it makes sense to clean both at the same visit: after the summer in September or October, and in spring. See the best time of year to clean solar panels. A clean roof around them helps too. See looking after a flat roof in Malta.

Booking

We arrange solar panel cleaning across Malta and Gozo and clean solar water heater glass and tubes at the same visit. Get a quote and mention the water heater when you book.