RENEWABLES


www.heatingandventilating.net


Clearing the path to renewable power


With gas boiler installations banned from newbuilds from 2025 and potentially phased out from all homes ten years after that, many more people will turn to heat pumps as the most efficient low-carbon alternative. Viessmann director Darren McMahon elaborates


T


his, combined with the rapid transition to electric vehicles, means our domestic power consumption is growing, at a time


when electricity prices are higher than they’ve ever been. As well as impacting already tightly squeezed household budgets, this risks putting the national grid under pressure, raising the unpleasant prospect of power outages in future. Small wonder then that more and more people


are now thinking about self-generation. But is going off grid realistic, and how should homeowners approach it if their electricity demands are going up not down?


Use, don’t sell


It is indeed possible to create a fully autonomous low-carbon heat and power ecosystem in the home


Vitovolt 300 PV system


Vitovolt 300 PV system + BYD battery


Vitovolt 300 PV system + BYD battery + electric vehicle


Vitovolt 300 PV system + BYD battery + electric vehicle + heat pump


Table illustrating different scenarios for the utilisation of self-generated electricity, for a typical Vitovolt 300 solar PV domestic installation


PV system size kWp 4 4 4 4


Total annual generation


kWh p.a. 3800 3800 3800 3800 Self


consumption %


30% 50% 80% 100% Self


consumption kWh


1140 1900 3040 3800 Grid feed kWh 2660 1900 760 0


Electricity unit cost


£/kWh £0.30 £0.30 £0.30 £0.30 Smart Export


Guarantee (SEG) tariff £/kWh


£0.03 £0.03 £0.03 £0.03 PV saving £ p.a. £421.80 £627.00 £934.80 £1,140.00


Above: Darren McMahon, director at Viessmann


for heating, power and hot water, but it requires investment and intelligent system management. Solar power has a central role to play here of


course, but we need to change how we look at it. Most PV systems are set up to export a large proportion of the (unused) generated power to the grid, whereas, in fact you should aim to use as much as possible – ideally all of it – within the household. That means thinking about it in the context of


other electrical demands and appliances. For example, if PV is combined with battery storage and an energy optimisation system, a gas boiler can be replaced by a heat pump to cover the heat demand, saving the gas energy used for heating completely and with only a minimal increase in electric consumption (<10%). If you think about the electric demand for a residential home with both a heat pump and electric vehicle, adding solar PV


26 July 2023


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