Solar Panel heater Project help!

[Guest]

Hi there,

First things first, I’d like to say this looks to be a great forum. There are some very interesting topics on here, and some very clued up people giving out priceless advice. Hopefully I’ve come to the write place.

I am currently in my final year at Manchester Metropolitan University studying for a degree in mechanical engineering. For my final year project, I have been given the task of coming up with some kind of back up system for a household immersion heater. This system must “green” powered using an array of solar powered photovoltaics (PV).

In the aim of getting a good mark, I’ve decided to look into installing a small DIY system to my home for testing purposes. But have come across a major stumbling block as I can’t seem to find a heating element or device that can be powered using such a low wattage give off from a small solar panel. I’ve searched high and low but have had no luck. I was wondering if any of the geniuses on here could point me in the direction.

Any help would be very helpful and much appreciated,

Thank you,
Stuart
.

[vtech]

While no authority on solar panel by any means, from what I have gathered, the "current" capability has been a major drawback so far. No doubt every practical approch still requires some sort of a battery back up which obviously makes it a non-green.

As you have already discovered, there are various Low-current devices that can be operated from solar panels ( LED's...etc) or even used as battery chargers. I am not aware of any resistive heating element that can be direct driven by solar panel(s) alone?

Did not think it is practical/economical with current tecnnology?

[minnie]

http://www.solarhome.org/

[torbjorn]

When using solar energy for heating of water, it is very inefficient to use photovoltaic cells and electricity as a intermediate step, due to the high price and low efficiency of the photovoltaic cells. It is much better to use the solar heat directly by circulating the water through heat exchanger panels on the roof. If the system is to be implemented in areas where frost is likely to occur in winter, then it should be filled with an anti-freeze compound (i.e. water + ethylene glycol) and this passed through another heat exchanger to heat the tap water. Provisions should be taken to stop circulation through the heat exchanger when there is no sun, in order not to cool down the hot water unnecessarily. Also, some kind of emergency cooling should be implemented to avoid boiling.
It is a good idea to use solar heated water for heating a big, well insulated accumulator tank (i.e. some m³), in order to have hot water on hand also at night. If the temperature of the tank water is not suifficient, then it is anyway good as input to a heat pump.