Oundle Transition Town Group

Hot water solar panels at Victoria Road, Oundle

Hot water solar panels at 1Victoria Road, Oundle

Our two solar panels were installed in October 2008 at a net cost of about £4000 and after the correction of some mistakes have been working well. The roof work was poor and some commissioning settings were not readjusted after completion of commissioning. The collectors are evacuated glass tubes made by Riomay.

The roof is east-west and therefore there are 2 panels, or collectors, one east and one west. There is a pump associated with each collector and these are started when there is a temperature difference of 6° C between the temperature of the water in the bottom of the tank and the collector(s). At this time of year on average the pumps together are on between 90 and 100 hours for a week and in the shortest days between 10 and 20 hours. A controller enables us to know water & collector temperatures, pumping speeds and whether the system is in “stagnation”. The system goes into stagnation when the water in the tank reaches 60° C. When this occurs the collectors can reach 140° C without any damage occurring.

The liquid (which includes antifreeze) passes through the collectors is separate from tank water and heats up the water when it is pumped through a coil in the tank. There are therefore 2 coils, one from the conventional boiler and one from the panels. The tank is of 210 litres and well insulated so there is very little loss of heat. The airing cupboard still works because we asked that the pipes should not be too well insulated.

We turn the boiler off in May and on again in September. We are saving about £10 to £12 per month in gas charges over a year.

Jeremy Rusher

The picture is of the westerly panel.