[TRNSYS-users] Question about a simple solar water heating system

[Jeff Thornton]

Solar fraction; the fraction of energy supplied by solar energy, increases with collector area and asymptotically approaches one as you increase the area.  That statement assumes that the solar collector system is allowed/controlled to meet the entirety of the load.  For example, if the collector pumps are controlled to turn off at 50 C and the load needs to be delivered at 65 C then you’ll have some auxiliary energy usage and the solar fraction will asymptote to something less than 1.  The other thing that may reduce solar fraction is a small load on two tank systems.  If you have a period where the load/draw is small, you can’t pull enough energy into the auxiliary tank from the water draw through the preheat tank and the auxiliary heater may turn on in the second tank to overcome the thermal losses from the tank.

Jeff

> On Mar 26, 2022, at 1:05 AM, Arian Bahrami via TRNSYS-users <trnsys-users at lists.onebuilding.org> wrote:
> 
>  Hi, everyone
> 
> I really appreciate your feedback regarding this question . I would like to know if there is a specific area collector where the annual solar fraction is at maximum value for a simple solar water heating system like the trnsys example or the solar fraction always increases with the area collector increase (no maximum point), Does it depend on location of the heater to be inside or outside the tank? 
> 
> Arian
> 
> 
> Sent from Yahoo Mail for iPhone
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