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Study of pump control in residential grid-tied solar domestic hot water photovoltaic-thermal (PV-T) systems
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Orientador(es)
Resumo(s)
A study of pump control focusing on active residential grid-connected solar domestic
hot water (SDHW) photovoltaic-thermal (PV-T) systems was conducted. The
main goal was to determine how the two main pump controls for this segment compare,
namely the differential temperature static two-level hysteretic control (DTSTLHC)
and the differential temperature static saturated hysteretic-proportional
control (DTSSHPC), given the dual outputs of PV-T technology: heat and electricity.
In order to do so, a dynamic PV-T collector model was developed for use in
transient simulations and incorporated into a SDHW PV-T system model. A substantial
number of annual simulations for each of the various locations selected were
conducted to encompass the best performances using each control, with emphasis
on multiple combinations of controller setpoints and mass flow rates. The results
show PV-T systems using DTSSHPC and optimised for maximum auxiliary energy
savings consistently outperforming those using DTSTLHC and optimised using the
same criterion, though the opposite was true when seeking to optimise the electrical
efficiency, with those using DTSTLHC performing best. However, the advantages at
best correspond to single-digit percentages of the annual thermal energy demand,
and less than 0.1% of the annual electrical efficiency. Similarly low performance
advantages were reached from the standpoint of primary energy efficiency and load
provision cost-effectiveness by using DTSSHPC, though not consistently due to the
inability to reconcile electrical, thermal and parasitic performance advantages over
DTSTLHC. Moreover, the advantages presented by DTSSHPC are low enough to
be offset by one additional maintenance operation, which systems using this control
are likelier to require first due to its complexity and higher switching frequencies.
Finally, a study on setpoint selection for differential temperature controllers,
namely DTSSHPC and DTSTLHC, for use in PV-T systems was also conducted
using steady-state methods, which revealed marginal differences between setpoint
selection for hybrid and non-hybrid systems.
Descrição
Palavras-chave
photovoltaic thermal pump control setpoint proportional