[RE-wrenches] Tube solar collectors

[Joel Davidson]

Hello Kelly,

Thanks for the feedback. Does anyone know if the Solyndra CIGS modules 
collect light from the backside?

Joel Davidson

----- Original Message ----- 
From: "Kelly Keilwitz, Whidbey Sun & Wind" <kelly at whidbeysunwind.com>
To: "RE Wrenches listserve" <re-wrenches at lists.re-wrenches.org>
Sent: Monday, July 20, 2009 11:15 PM
Subject: Re: [RE-wrenches] Tube solar collectors


> Joel,
>
> We frequently will orient tube collectors on east or west facing roofs 
> with
> very good results. However, pointing a solar collector toward the south 
> will
> always produce more energy, as we all know that the greatest solar energy 
> is
> concentrated around noon.
>
> The choice of whether to tilt comes down to efficiency, cost, and 
> aesthetics
> - and sometimes overheating issues. With a tube system care must be taken
> not to oversize the collector in proportion to the tank. If a customer 
> wants
> to maximize heating throughout the year I recommend a larger collector
> tilted steeply toward the winter sun angle. This not only maximizes winter
> production but, more importantly, attenuates summer heat gain.
>
> It's interesting to note that, as Apricus tubes have the collector surface
> circumferentially, they will collect heat from the backside (a significant
> factor during northern summers).
>
> Another design factor is that the heat pipes must always maintain a slope
> for heat transfer. Thus, tilting up on the east or west-facing roof is
> necessary if the tubes are to be oriented N-S.
>
> -Kelly
> Kelly Keilwitz, P.E.
> Whidbey Sun & Wind, LLC
> Renewable Energy Systems
> NABCEP Certified PV Installer
> 987 Wanamaker Rd,
> Coupeville, WA 98239
> PH & FAX 360-678-7131
> sunwind at whidbeysunwind.com
>
>
> On 7/20/09 8:09 AM, "Joel  Davidson" <joel.davidson at sbcglobal.net> wrote:
>
>> Hello Kelly,
>>
>> I saw your website photos (nice work). Do you think that tubes oriented 
>> (1)
>> east-west would and (2) flat would perform as well as your tilted
>> north-south tubes?
>>
>> Joel Davidson
>>
>> ----- Original Message -----
>> From: "Kelly Keilwitz, Whidbey Sun & Wind" <kelly at whidbeysunwind.com>
>> To: "RE Wrenches listserve" <re-wrenches at lists.re-wrenches.org>
>> Sent: Monday, July 20, 2009 12:12 AM
>> Subject: Re: [RE-wrenches] Tube solar collectors
>>
>>
>> All,
>> Apricus ET's have a cylindrical absorber surface, which are significantly
>> better at capturing low angle of incidence energy. I have both a 
>> Thermomax
>> (with flat collector plate internal to the tube) and Apricus collector in
>> parallel on my own home and see significantly better temperatures early 
>> and
>> late in the day on the Apricus collector.
>>
>> IMO, ET's have a distinct advantage in our cool, windy, and low-snow
>> environment (northern Puget Sound).
>>
>> Kelly Keilwitz, P.E.
>> Whidbey Sun & Wind, LLC
>> Renewable Energy Systems
>> NABCEP Certified PV Installer
>> 987 Wanamaker Rd,
>> Coupeville, WA 98239
>> PH & FAX 360-678-7131
>> sunwind at whidbeysunwind.com
>>
>>
>
>
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