Thermal load does not change when changing different heat transfer integration mode and PV area

asked 2018-11-15 21:55:54 -0600

camille
23 ●2

updated 2018-11-16 07:32:47 -0600

11931 ●203 ●9 https://www.nrel.gov/b...

In the documentation of EnergyPlus, it is said that "If the integration mode is selected as ‘DECOUPLED’ then no adjustments are made to account for energy extracted in the form of electricity. If the integration mode is selected as ‘INTEGRATED’ then the energy extracted in the form of electricity is removed from surface heat transfer calculations using a sink term."

However, the heating and cooling load do not change when I change the heat transfer integration mode from 'decoupled' to 'Integration'. In addition, the heating and cooling load do not change with the PV area when I set the integration mode as 'IntegratedSurfaceOutsideFace'.

Is there any problem with my settings or just EnergyPlus actually can not handle this issue?

Can anyone help me with this problem? I will really appreciate it!

P.S: the version of EnergyPlus I use is V8.7.0

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answered 2018-11-16 04:22:28 -0600

adambgnr

759 ●1 ●2 ●7 http://www.linkedin.co...

If you have a decent amount of insulation, the effect of this on the thermal load of the zone is very small. Especially if not the whole building surface is covered with PV, just some part of it.

The effect of the reduced heat gain due to the removed energy in form of electricity is similar to changing the albedo of the surface. As an example, if your PV is 18% efficient, then taking into account the surface "cooling effect" of the drained electricity is roughly equivalent with reducing the surface albedo during daytime by 0.18 (e.g. from 0.9 to 0.72), which might not affect your cooling loads that much.

The removed heat is more interesting for the PV itself (if the Integrated Surface Outside Face option is used to calculate its temperature), as the efficiency if the PV is dependent on its temperature.

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Thank you so much! I think you are right! The impacts of PV on building thermal load is ignorable as there is no air gap between the roof and PV panel in my model.