Solar PV plus air source heat pumps: a case study of Donyatt village hall
Posted by Cathy Debenham on 5 August 2011 at 9:34 am
South east facing solar PV panels on a nearby roof got David Willis thinking that they might be an option for Donyatt Village Hall in Somerset.
"They were facing a bit east of south east, and yet the performance is better than my solar pv panels on a south facing roof with slight shade first thing in the morning," he says.
This gave Willis the idea to have two arrays of solar panels installed on the village hall. One facing south east and one south west. There are two inverters, as the different arrays perform best at different times. The former array starts up earlier, and the latter goes on generating longer in the evening.
The solar panels are part of a major village hall improvement, that had Willis fundraising non-stop for several years. In addition, there is a new highly-insulated extension, four air source heat pump units for heating, a safe children's play area, insulation and draught proofing, new loos with light sensors, and more still to be done.
Heating was a big expense for the village hall, with very inefficient radiant heaters up near the ceiling. "They heated the hall quickly, but were very inefficient moneywise," says Willis. His feeling that air source heat pumps would be the most cost efficient way to heat it was confirmed by an energy survey, which covered all aspects of energy saving options.
The hall is now heated by four air source heat pump units, each connected to a blower unit in the ceiling of the hall, and initially it took a while to learn how to get the best out of it it.
"It heats quite fast and very quietly, but initially unevenly, which causes a bit of a draught. But that settles as it warms up.
"Getting used to the controls was difficult. There are so many things you can do, so people new to the hall would press all the wrong buttons. People are used to it now, and in the second half of the winter complaints dried up."
As the heat pump hasn't been in a year, Willis hasn't done a cost comparison yet. As the hall was heated solely by electricity previously, he expects cost to have fallen significantly.
The solar PV panels cost £28,000 with funding from the Low Carbon Building Programme and the Community Sustainable Energy Programme (both now closed). The main tranche of the £9,000 funding for the air source heat pumps was Making it Local.
As a by product of all the village hall improvements, Willis has become a bit of an expert at raising funds. His tip is to prove that what you are doing will be "wonderful for old people, wonderful for young people, and wonderful for racial mix; that you have good policies and activities in place for all; and that it will be good for community cohesion".By Cathy Debenham
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