Tuesday, 26 March 2013
It's been just over a year since the solar energy photo voltaic panel (PV) system has adorned this house and has provided me with another distraction - I do love my stats! Additionally it has provided many surprises along the way, anyway, let's start at the very beginning...
On Mersea Island it is apparent there has been a substantial take up of the electricity micro-generation using solar panels as they are clearly visible on many homes. Indeed, there are a handful of proactive installers based on this relatively tiny patch which would contribute towards the prevalence.
One of the first things I discovered when having decided to embark on having an installation was to invite quotes from the local teams as well as further afield. In total I contacted six, all but two visited and quoted for different configurations, that was the first puzzle. I settled on a fairly local off-Island company, Igloo Environmental, who already had happy customers on the Island.
This property does not have a South facing roof, the pitch roof is East - West with additional flat roofs, one which is fairly large. An initial proposal was for brackets to angle panels on that flat roof, but the first surprise was that panels can either be laid flat with only ~10% reduction in output OR be installed on an East - West roof with a similar reduction. Igloo eventually came up with an optimised solution with panels on the flat roof, on the East side of the property, positioned as far East as legally permitted and panels on the West facing pitch. In fact the West roof is slightly inclined toward South, even better!
The outcome of this is that the flat panels receive sunlight much longer than if they were on the East facing pitch, so overall we get a really good result, only marginally less than an ideally aligned house with a South facing pitched roof.
Igloo were up against a bit of a deadline, only partly my fault, principally due to interest and take up peaking as deadlines approached. This resulted in a dearth of components, mainly the panels themselves. However, all parties were delighted that deadlines were met and everything worked first time. Since the original installation they have been back just once and then only to address a couple of minor, aesthetic matters.
Another major surprise was that when everything was connected and tested I noticed that it was immediately started generating electricity even though it was overcast. It intrigued me that none of the sales pitches had ever mentioned that the generation depends on the level of light rather than sunlight. A good selling point, surely?!
Another key point that only really has any clarity when it is explained is what the Feed In Tariff (FiT) really is. In a way FiT is a bit of a misnomer, because the main income is from the total electricity units the system generates whereas the Feed back to the grid bit is estimated at half the generated units and paid at something like 3p. I managed to scrape in when the rates were higher, around 43.3p per kWh unit generated, even though it is now around 20p/kWh the sums still work out very favourably.
All the companies provide detailed graphs and figures of expected generation, in this case Igloo predicted that in the first year we could expect to generate 2954kWh whereas the system actually provided 3432kWh, a 16% excess, result! Furthermore when the system is generating more than you use, that is when the surplus is fed back into the grid. A light on the main electricity meter indicates when this is the case. It is quite hard to accurately calculate how much is returned but my billed usage has dropped from around 5000kWh to 3000kWh per annum. So roughly the system has made up that 2000kWh therefore an estimate for the surplus would be 1432kWh which the provider can resell at around 17p per unit.
Having the system does make one much more aware of daily usage, early on I would go round the house looking for lights I could switch off to trigger full parity for 'free' electricity. Now I am careful not to switch two power hungry devices on simultaneously, so kettle followed by toaster and only slightly less obsessed about switching devices off. However, I am still a bit crestfallen every night when the light finally goes!
As an investment it is brilliant, to receive tax free 'interest' of around 25% pa is incredible, the cost was under £8.8k and well worth borrowing for. I know there is criticism that this is only financially accessible to some but it is reducing energy usage. In an earlier post I relate how we had bees in the roof space and their re-deployment. That renovation also included serious extra insulation along with further upgrades to the main roofspace insulation. This is just part of a cunning plan to reduce costs and energy consumption and, despite a certain amount of ignorance, I embarked on the solar energy journey to be environmentally responsible rather than to make any money back. That's a rather pleasing by-product of being a bit naïve, a somewhat green Green!