Solar Panel heater Project help!

[Solar_Stu]

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
.

[mike95490]

Sounds like the assignement is inherently due to fail. Using PV panel electric, to heat water, is nonsense. What you want is Solar heat collectors made for water. What you wrote is "assignment is to use PV electric to heat water".

[niel]

stu,
i am surprised they would ask you to do this with pvs as thermal panels are much more efficient at producing heat and much cheaper too. it can be done with pvs though, but will depend on how much heated liquid you'll need and how fast. at best you will get 3.14 btus of heat per watt. you will need to have a resistive load that can be submerged and there are some at this address: http://www.hydrogenappliances.com/hotwater.html
be sure to match up the wattages so that the load is rated higher than the pvs best output rating. of course observe the voltages too as a 12v element goes with 12v pvs. even as small systems go you will pay quite a bit for the pvs. does this help? let us know if you actually do this, what grade you get, and the layout of the system you tried.
oh, and don't forget you will need a container to hold your liquid in with insulation for efficiency, although i deem this a toatally inefficient way to heat a liquid.

do note that one posting is sufficient on asking a question and i eliminated the other. when posting a question pick the best catagory you think it'll fit, even if it would fit more than one, and only post it once.

[Roderick]

...
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).
...

Thank you,
Stuart
.

Hi,

The others have already mentioned what is taken for granted today with PV - that it's a really inefficient way to heat.

I'd encourage you to speak with your professor. Perhaps you misunderstood the green requirement, or it wasn't stated clearly. A solar thermal panel would definitely be considered green by nearly everyone.

If this were not the final project, or if it was for a Ph.D., I would ask whether I might have been thrown a set of invalid requirements, which I was expected to question.

I've always been impressed, often to tears, when a student sees the big picture and delivers a solution to the underlying problem, not just an answer meeting the specifications.

Maybe you could flow water over or under the PV panel, and use the electricity just or pumping? Or something similarly creative. The sun is really good at heating water. Without any concentration, you can put a black container filled with water in a well-insulated box, with glass over the top, and BOIL the water.

Good luck,
Roderick.