cannot install a solar panel in the roof or a cupboard.
Solar panel life expectancy is anything from 10-30 years, but how long are the systems given?  Geezer

solar water heaters

The estimated payback time for SWH was worked out when electricity was 16cents per kw/hr. Because I have seen the 5 to 7 year figure for years now. It is now 87 cents per kilowatt hr. What will the estimate be when Eskom, in order to give ever increasing bonuses to an incompetant political management, changes the priuces up to R1.50 per kw hour by next year? Can some electrical engineer comment please.

If one uses the tubes instead of the panels, they cab be replaced almost for ever. The rest of the system is just pipes, fittings and a storage tank. That changes the picture about the longevity of that particular solar system.

The challenge with tubes instead of panels is that the tube system generates higher temperatures which cause higher pressures when you do not regularly use hot water throughout the day and that causes leaks. Perhaps someone knows about a steady pressure relief valve that will steam off during the day so the conventional geyser pressure release valve will not burst and have to be replaced all the time.
I would really appreciate a scientific response to this as we haqve sufficient annecdotal evidence.  Case

Heat pumps

One of the disadvantages of solar not mentioned is that if you bath at night, the geyser cannot be heated by sunlight during the night, and thus an electrical heater has to kick in to ensure hot water in the morning, which reduces overall electricity savings. I understand that Eskom are supporting Heat Pumps and are apparently about to announce a subsidy soon.  Doug

Solar vs Heat pumps

When building our new house we installed gas geyseys - they supply hot water on demand with no need for hot water storage tanks. Low capital cost and low running cost.  Bill Richards

Read more: http://www.iafrica.com/iafrica/706318.html