In 'Powering ahead 1: the journey begins', Dr Mark Everard outlined the journey towards investment in a photovoltaic array on his family's house in North Wiltshire. Here he gives an account of the 'warts and all' experience of installation and the first months of operation.
Installation of our photovoltaic (PV) system was pretty painless, spanning about a day-and-a-half with time either side to erect and dismantle scaffolding. Some roof tiles were lifted to allow support brackets to be bolted to the rafters (no additional reinforcement was necessary) then replaced to maintain weather-proofing.
The monocrystalline PV panels were then bolted to rails connected to the brackets. Wires from each were fed into an inverter unit bolted to the inside end-wall of the loft.
This converted the panels' DC output into AC, which was routed to a switch and control box and fed into a spare gangway in our existing fuse box. From there, power could flow into our appliances or outwards into the grid. It was that simple!
Turning on
My daughter phoned me after school on the second day to tell me that we were currently generating just over 2kW of electricity. Although there is not the same artistry involved in bought-in technology, the sense of moving from consumer to producer was as satisfying as eating runner beans planted and nurtured by your own hand.
A portable device, powered (naturally) by an integral solar panel, receives a radio feed from the meter. It sits on our living room window sill and informs us about our momentary, daily and cumulative power production. It does a whole lot more things besides, but these are accessible only by the more technologically-gifted members of my household!
Empowered
The juice is flowing as I write some five months later. Some is powering my computer, fish tanks and stereo. The excess on this bright morning is being exported through the meter to power other homes in the village. It feels good, like sharing a glut of courgettes from the allotment. And, just as we buy vegetables from the supermarket out-of-season, so we will buy energy back from the grid in the dark or when the kettle or cooker exceed our own generation.
It will not surprise weather-obsessed British readers that generation varies dramatically with sun orientation, cloud and haze. Peak output during the first month (late May to late June) varied from just over 3kW under full sunshine (theoretical peak generation is 3.145kW) down to 0kW (every night).
Daily variation was dramatic, from 21.29kWhr on a day of blue skies down to a less impressive 3.5kWhr under persistent heavy cloud and torrential rain. Nevertheless, total generation during the first month, admittedly straddling mid-summer with long days and generally bright weather, was 441.5kWhr (or nearly half a megawatt hour which sounds bigger!) After five months, total generation has exceeded 1.7MWhr.
Though the clocks have gone back, and days are now a lot shorter with the sun at a lower angle, we'll not necessarily be buying in substantially more energy. Photovoltaics are all about light, unlike solar thermal systems that trap heat.
They are also most efficient at lower temperatures, though of course winter days are shorter and the weather may be duller. However, at this moment on the bright, high-pressure day on which I write, with sunshine beaming down from a clear sky after a -5°C frost, the system is kicking out 2.21kW.
On a charge
Our photovoltaic roof is still the subject of discussion around the village. This is overwhelmingly positive ("Looks nice!", "How much is it saving?", "Wish I could afford it!", "Well done getting one over on the planners!"), with just one in denial ("...but scientists say that climate change has been disproved!")
However, the most important views in the village, in our perhaps less than humble opinion, are our own as it is our money, our roof and our commitment to a principle! Did we make the right decision? Unquestionably.
Fuelling the ‘bottom lines'
So what of the ‘triple bottom line' outcomes for sustainability?
Well, there is a clear environment benefit from lower lifetime emissions. The material inputs to modern monocrystalline PV panels are not too horrendous, and the long and guaranteed design life of these systems amplifies their benefits.
Economic benefits to us are favourable. Perversely, this saw me looking forward to our first full quarterly electricity bill. When it arrived, a glitch in the paperwork meant that payments back to us had been omitted; instead of credits we had a bill of £83.44! Our supply company was quick to remedy this with a cheque for the missing credits. This helped clarify two of the three strands of benefit: the Feed-in Tariff (FIT) and our payment for exported energy.
FITs, you may know, are set in this first year of registration at 41.3p for 50 per cent of output and 44.3p for the other 50 per cent (FIT plus 3p for a ‘deemed' export to the grid of half the energy generated). FIT payments are index-linked and contracted for 25 years, though the tariff is planned to decline in successive years as renewable technologies become mainstream.
Our FITs payment, including ‘deemed' exported energy, totalled a very respectable £683.94, dwarfing the energy bill and providing us with real income from our substantial capital outlay.
The third strand of benefit, energy costing just shy of 12p per unit displaced by ‘home grown' generation, was revealed by comparison of our post-PV bill (£83.44) with that for the same summer quarter the previous year (£238.15 which was an estimate so let's assume the ‘real' bill would have been £200). This yielded an additional benefit of £116.56.
This net return to us of £800.50 across the three benefit strands (FIT + export + purchase averted) is, of course, a ‘best case' since it covers the mid-summer period of longer and mainly brighter days.
But current performance is well ahead of the theoretical payback of fractionally over 11 years. (This equates to an annual return on investment of a tad over nine per cent, which is handsome compared to current interest rates.) For the full picture, we'll have to wait for another year.
There is the additional personal benefit of a rise in the value of our house, though we have no intention of selling.
There is also the benefit to the nation (and world) of cost savings from damage averted from traditional fossil fuel or nuclear generation, not to mention competitive advantage to the British economy of leading on one of ‘tomorrow's technologies'.
Then there are the social benefits. Less pressure on other people from emissions and resource extraction, and an input to our local grid. We also like our new toy, and for many reasons, significantly including making good a value-based decision.
From the sustainability angle, this is a win-win-win outcome.
Resistance in the circuit
There remain, of course, barriers to the mainstreaming of a technology that could virtually cost-neutrally be embedded in new build and a lot of major refurbishment for the benefit of tenants, national commitments and the global climate.
There are perceptions to be redressed that the technology is anything less than mature, the case to be laid out clearly about lifetime value, and hints and tips to help people navigate the often unenlightened planning system and the minefield of ‘variable' suppliers.
My article in the parish magazine and these in ‘the environmentalist' have already proved helpful to some people in getting over perceived hurdles, aiding just that little bit the ‘mainstreaming' of a transformative technology.
Some institutional obstacles remain to be battered down. A villager was told by the County Council that he couldn't have either PV or solar thermal panels. I sent him home with a note about the 2009 amendment to Part 40 of the General Permitted Development Order; he phoned back an hour later to say that the Council now agreed that he did not need planning permission.
Clearly my own struggle with the same planners some months before had not sunk into departmental consciousness. This reinforces prior advice to do your homework, keep pushing, and don't take ‘no' for an ill-informed answer!
Then there is the threat of government axing FITs - the major contributor to the financial viability of these schemes - as part of its austerity measures. I am all for prudence, but far less in favour of blocking transformative technologies in favour of unsustainable defaults.
Charged up
Our family decision to push ahead with home-scale renewable energy was substantially values-based. However, we're far from big earners and we've got to eat, so the sums had to add up!
From all perspectives, this has been a good decision about which, notwithstanding the time we've had to reflect, we have no regrets. When we're out in the daytime, the house is powering the rest of the village and that's a great feeling.
Every time we walk past the portable display unit, and often just out of curiosity, we take a look at how we're doing. It probably gets watched even more than the fish tanks!
I hope to write again next year to relate our experience across all four seasons. Right now, we have only positive things to say, and also plenty of lessons to share about the importance of homework and persistence and of how to sort the wheat from the chaff amongst suppliers.
With a little perseverance, this should be your experience too of a ‘breakthrough' technology that has now truly broken through.
