Energy Efficiency: Power Puzzle or Perfect Sense ?
So, it's about time to get some of those decision making neurons firing with a seemingly impossible equation regarding energy efficiency as posed earlier today.
Yes, I know the initial reaction - "surely 1600+970+850 > 1250 ?", well yes, that would be correct in an arithmetical sense, but that doesn't necessarily mean that the above isn't mathematically correct too, else I'd be spending money on importing electricity, which I'm definitely not !
Well, there's no trick to it - here's the explanation - A domestic solar PV system (typical UK installation of 16 panels/4kWp) in overcast conditions is generating ~1.25kW, of which ~400W is being used locally to power the house, leaving ~850W spare for export to the grid. Of the ~400W being consumed, ~130W is meeting the home's baseload demand and feeding a low power electric pump which forms part of a solar thermal system feeding 970W of heat into the Domestic Hot Water (DHW) store. The remaining 270W is being consumed by a high efficiency split unit air to air heat pump which in current ambient conditions (16.5C) is actively delivering around 6x more heat per kWh of electrical energy consumed than a standard resistance heater (COP6), therefore ~1620W.
Seemingly impossible? - no, just the application of the same joined-up thinking which questions the relevant capacity of grid-connected domestic battery storage systems.
Decisions, decisions, decisions ... ? .... Vriconian, using joined-up thinking to help spark a route forward ....
Still as puzzled?, or perfect sense ?
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