Hi

About £35. See redrok.com. Payback is quite practical with such a
tracker.

That's a good website. Although making it windproof would be fun.
Maybe a mylar lined parabolic mirror directing extra sun into the
house would be worthwhile. Directing extra light into the bathroom
which is on the north side of the hosue would be good.

Yup. You would have glare to deal with: you'd need to direct the light
up towards the ceiling. And I'd be a bit cautious about focussing the
sun into one small spot, a deliberately not-really-parabola might be
preferable. But I think this is basically a good way to go, you get
heat and light very cheaply.

I did something similar using a flat plate mirror, just mounted it apx
horizontal under the window on the outside. Doubled the light level in
the room. Direct sun mainly hits carpet and furnishings, whereas
reflected sun mainly hits the white ceiling, so such large light
increases are quite practical. Plus you get the birds landing on it,
and the cats sunbathing on it.


There are a lot of different technologies, a lot of different designs
with each one, and a lot of differnet takes on them all. I definnitely
wouldn't assume active solar heat is no-go - tho most systems are.

Lets have a think. Oil heating costs about 1.4 pence / kwh.

Are you sure? I dont know, its just that gas is more than that.

If my 8sqm freestanding DIY collector cost me 200 quid, it would have
to produce a total of 14284 kw to pay me back. If it averages 1kw from
autumn through to spring, an average of 7 hours a day, call it 250
days... that's 1750 kwh a year. That's 8 years!! Oh well, I'd just
have to be thinking of the greenhouse gasses saved.

I havent done the maths here, but ave of 1/8 kW per sqm sounds much
too low.
I dont know what kind of collector youre considering, all I can say is
big trackers can pay back according to previous calcs. But it does
depend how you design them. Somewhere I've got detailed figures on
this one: want me to mail them? Might be of interest.


As an aside - remember my solar coil for the pool? I was forced to do
as you suggested and divide it into seperate circuits because the
bearings in my pump are starting to go, it sounds very noisy now. I
bought 6 T-pieces and made it into 4 seperate circuits and now the
water gushes out the other end instead of trickling. I shall replace
the pump with a less powerful one - a 1/4 horsepower one to save
leccy.

Right. I'd be tempted to just run it slower, by using a series
impedance or transformer. Sounds pretty lousy tho if its crapping out
already.

Now if you turn your coil into 112 parallelled one foot long sections,
you'd only need 5w of pumping

I've also bought some polythene, 36sqm for 15 quid, trouble is it's
not as clear as I hoped and I may not use it, hmmm.

I reckon if you get more than 50% through it should gain you. Youre
really losing a lot with an open collector. It wont matter that theres
light scattering.

Wish I had the time to actually do what you are.


Regards, NT