Solar water heaters

I bought my solar heater in June 1982 for Lm575 (first quote was Lm650). This consisted of a 130-litre stainless steel tank located inside the washroom with a 1.2 kw element booster, a two-square metre solar panel on the roof made of copper serpentine tubes and aluminium fins and a circulating pump for the transfer medium (i.e. a closed system).

I was advised that a closed system was much better than an open system, due to the hardness of our water and was also told that the payback period for a family of four would be about five years.

The result was:

(a) about Lm12-15 maintenance every one or two years to hold the pressure of the circulating pump.

(b) obtained real hot water at 60ºC+ in July/August when hot water is not required since the cold water tap will also be hot.

(c) The only months that one obtained hot water that was required and without the help of electric booster were May/June/September.

(d) For the rest of the remaining seven months, the electric booster was heating up 130 litres of water (although for a smaller temperature difference than if it was fed cold water) when one often required say only 15 litres to take a shower!

The end result was that instead of a payback I overspent grossly on my electricity bills (I estimate Lm60 a year) and hence added to, instead of relieved, Enemalta's load!

The solar heater I bought 20 years ago was a very good model, and is still in very good working condition. The first step I had to take when I realised my predicament was to install a seven-day timer to control the heating hours. Later I removed the electric booster and just fed the water heated by the solar heater to small electric water heaters (30-50 litres) to be used with timers as necessary.

Although I made considerable financial losses from this experience I do not wish that others make the same mistake. Some actions that, in my opinion, should be taken to obtain optimum results are:

1. An authoritative body (MRA) should educate the public how these solar heaters are to be installed to obtain optimum results. There is no point in saying that Pembroke housing are being supplied with solar heaters unless they are installed to function efficiently since if not, the reverse will happen.

2. Minimum specifications and efficiency figures for solar panels need be established and be published.

3. The pros and cons of a closed system versus an open system are to be evaluated. An open system should be more efficient and maintenance-free compared to a closed system, which has a circulating pump. But then one needs to control the salt deposits from our hard water possibly using displacement systems, which today are available.

4. Control experiments for households over a whole year to compare hot water cost from a solar water heater versus an electric water heater should be set up to quantify exactly the efficiency of such systems. Statements by suppliers of such heaters, that they are 80 per cent efficient with a payback period of three years, I would not accept. Only from such experiments can one really determine the real payback period, cost saving for the user and the load saving for Enemalta.

5. These heaters should not be worth purchasing, I feel, if their price is above Lm250. This is the price I had quoted when I wrote a similar article in this newspaper about ten years ago. This is the price (and lower) that these items are sold in Israel and Cyprus and that is why all their rooftops have such a heater (besides being compulsory by law in Israel).

In conclusion, it is very sad that after 20 years that such units have been introduced in Malta, we are still talking along the lines outlined above and still do not have a definite plan which can be implemented to use our abundant source of energy, the sun, effectively, efficiently and competitively. Will this take another 10 years to happen?