That's an interesting idea.  I know house roofs can be insulated from the
outside as well as from the inside.

Reflectix <http://www.reflectixinc.com/basepage.asp?PageIndex=565> is thin,
light weight, and easy to handle.  I was thinking along the lines that
there might be some way to attach it to the ceiling of the poptop, and then
cover it with some kind of auto ceiling upholstery material to hide the
"tin look,"......I guess it could be glued, but I wouldn't want to try
anything permanent unless I was sure it would work and look good.  I
wood-paneled another van (not a VW), and used Reflectix behind the panels,
but that was simple because I had metal beams to hold the screws.

Just brainstorming...photovoltaic sounds good, and very useful, too!
Patti

On Thu, Jun 11, 2015 at 8:15 PM, PSD <psdooley@verizon.net> wrote:

> Sounds like a principle similar to a double pane window.  The air gap acts
> an insulator.
>
> -----Original Message-----
> From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of
> Richard Smith
> Sent: Thursday, June 11, 2015 11:01 PM
> To: vanagon@GERRY.VANAGON.COM
> Subject: Re: how to cool a poptop?
>
> They have mainly disappeared now, but for many years the taxis in Hong
> Kong (Toyota Crowns) had a dual roof. On top of the regular roof, and
> separated by about an inch, was another roof. The idea was that the flow
> of air between the two roofs, as well as the shade, I guess, would make
> for a cooler car. Perhaps this was because there was no air conditioning,
> or to ease the burden on the air conditioner.
>

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