Re: [TRNSYS-users] Theoretical flat-plate collector

["Jeff Thornton" <thornton@tess-inc.com>]

<I'm using Type 73 to model a flat plate solar cllector for domestic
hot water. What mostly surprise me is that the efficiency of the
panel, which is calculated as (useful energy) / (incident solar
radiation),  is lower than expected (30%-40% as a maximum, instead of
80%-90%) even if I maximise all the parametres that affect the
efficiency. is it a common>

Un-glazed collectors can reach 90% efficiency at low temperatures,
single-glazed collectors are typically in the 80% range at low
temperatures and double-glazed collectors are in the 70% range.  With
elevated temperatures, the efficiency drops rapidly and 30-40% is not at
all unusual.  You can easily pre-calculate the expected efficiency using
the efficiency equation:

Efficiency = FrTan - FrUl*(Tcollector-Tambient)/Incident Solar

Jeff



Jeff Thornton
President - TESS, LLC

22 North Carroll Street - Suite 370
Madison WI 53703 USA

Phone: 608-274-2577
Fax: 608-278-1475
E-mail: thornton@tess-inc.com
Web: www.tess-inc.com