Hi Rob,

I use a 12V, 15W photovoltaic panel to drive four cheap 120mm
fans (the type used in PCs), two at the top to exhaust hot air
and two at floor level to blow cold air in from under the obs,
where the air is coolest.
Works great - the stronger the sun, the faster the fans spin.
The PV panel is also connected (in parallel) to a charge controller
so any excess energy is used to charge my 12V gel batteries.
The fan circuit is switched off in Winter, or when weather is
lousy, so all of the energy from the PV is used to charge the
batteries.
You might need a higher rated panel and more fans of course -
I'm based in the UK..

HTH,
--
Rob (~52N, ~1W)

>-----Original Message-----
>From: Flip_Top_and_Clamshell_Observatories@yahoogroups.com
>[mailto:Flip_Top_and_Clamshell_Observatories@yahoogroups.com] On Behalf
>Of robridens
>Sent: 22 June 2009 04:46
>To: Flip_Top_and_Clamshell_Observatories@yahoogroups.com
>Subject: [Flip_Top_and_Clamshell_Observatories] heat
>
>So how are you guys dealing with the heat buildup inside these
>things?seems like the plastic on the telescopes would melt.any advice
>would be helpful. Rob Ridens Evansville,In
>
>
>
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