Rick Thomas on solar

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Rick Thomas <rick@wirecomms.com> reply-to rick@wirecomms.com to joseph.dolittle@gmail.com date Fri, Sep 5, 2008 at 2:00 PM subject Your Solar Generator, a few thoughts.

hide details Sep 5 (3 days ago)


Hi I recently came across your site. Your ideas on solar power generation closely match mine. In the near future (I hope) I will be moving to the East coast of Spain. I therefore thought that a solar generator would be economically viable (Not so in the UK).

My idea is to build a Compact Linear Fresnel Reflector array. About 20 square meters in size (total size depends on power needed). Using this to generate steam to power a small steam engine coupled to a generator, any power that we don't use will be sold back to the Grid generating extra income. Waste heat will be used to heat the house and pool in winter.

Building the array will be simple, however doing something useful with all the heat generated is a little more tricky (for me at least).

Here are my first thoughts...

Use oil in the primary collector loop, this will reduce the need for high pressure pipes to be used. As a guess the temperature of the oil will go up to between 400 to 600 C depending on the mirror area and the amount of insulation I use.

Maybe use a thermal store, i.e. a BIG block of insulated concrete.

Use a heat exchanger built into the boiler to generate the steam. Use a steam engine, in particular one of these http://www.greensteamengine.com/index.html coupled to an alternator to generate the electricity.

The above is just the bare bones idea. Obviously it will need filling out.

The main idea came from the reading about the Liddell site in Australia See http://solarheatpower.veritel.com.au/mainmenu.html go to projects. The research section is interesting as well.

I built a small unit, about 1 meter square (6 mirror rows) this summer to experiment with the concept and play with the tracking System. I used a satellite actuator to provide the motive power, it worked well at 12V, plenty of torque. I started by using a LDR based tracker, although it worked, it didn't seem to be sensitive enough. I then played with a green LED based tracker, much more sensitive it tracked perfectly, almost too sensitive.

I also came up with a way of individually adjusting each mirror row so that one actuator would move them all in sync, unfortunately I didn't take any photos of it.

Anyway, enough about my ideas.

My thoughts.. Using oil in the collector probably works out cheaper than installing pressure pipe. A steam engine rather than a turbine, as you don't have to gear it down and it has higher torque. Probably easier to regulate the speed as well.

All the best with your project, I hope it all goes to plan and to budget <Grin>

By the way, have you seen this stuff.. http://www.reflectechsolar.com/pricing.html