SOLAR ELECTRICITY GENERATION AND WATER HEATING: REFLECTIONS ON RENEWABLES
IN A 3 BEDROOM BUNGALOW IN BAILDON
1.1 We were first inspired by the Energy Show at Olympia [in 1970 I think] when we saw a little rotating machine like an anemometer, powered by the sun through a photo-voltaic cell. We thought, 'That is the future.' We saw them working on a considerable scale in Botswana from 1993-7; there, the sun powers telecoms and water-pumps, recharges batteries etc.
1.2 We researched the various options for reducing our carbon footprint. The Energy Saving Trust [EST] www.est.org.uk is the best objective source of information, pointing the way to many others. It has excellent fact sheets on all renewables.
1.3 We saw a small wind turbine at Slaidburn next to Dale Head church, a building which is entirely off-grid. We decided against wind energy for us. Our turbine would be too small, too hedged about with trees [which would cause turbulence] and too close to too many neighbours.
1.4 We have seen ground-source heat-pumps in the new building of Watson Batty architects behind Marks and Spencer in Guiseley, and in St James Church, the White Church , on Otley Road , Baildon. We decided against a ground-source heat-pump for ourselves as it would normally mean taking up the floor and installing under-floor heating.
1.5 To be eligible to receive from the Government Department of Trade and Industry a Low Carbon Buildings Programme grant for renewable energy installations www.lowcarbonbuildings.org.uk , we had to insulate all the walls, put 270mm of insulation into the loft, have double glazing, and install low wattage bulbs wherever practical. The nation-wide amount for grants was increased from 2007 but the amount per grant was greatly reduced.
1.6 We consulted Mervyn Flecknoe < firstname.lastname@example.org > who has solar thermal panels and photovoltaic panels. We visited Gibson's Mill, the National Trust's property at Hardcastle Crags, Hebden Bridge ; this is entirely off-grid.
1.7 We got in writing a statement from the Planning Department of the Council that no planning permission was necessary as long as the solar panels did not project more than 100mm above the existing roof.
2.1 We decided on solar thermal panels for heating our water. Evacuated tubes are said to be slightly more efficient but have, reportedly, a shorter life.
2.2 We decided on photovoltaic [PV] tiles for generating electricity. This seemed sensible because we needed to re-roof the bungalow. Otherwise we would have installed photovoltaic panels.
3 FINDING THE CONTRACTORS
We needed a willing and efficient roofer to cooperate with the solar energy firms. We found one in Turner Bros, Slaters, of Baildon T 01274 584965 and 01274 427531. Bill Pringle of Turners proved to be a superb choice; he did all the work perfectly. We took another quote from a roofing firm recommended from a job they had done in our area: Pickles Bros of Leeds T 0113 2752620. They gave an efficient quote of about £2000 more than Turners.
The Energy Saving Trust has a list of approved contractors for renewable energy work. If a firm is not on this list, no government grant is available. We asked for quotations from On Tap Solar of Huddersfield www.ontapuk.com who were just starting up in the solar business; and from Solar Utilities of Rotherham www.solarutilities.co.uk : they both had the advantage that they said that they could do the PV and solar thermal work. Neither had much experience, however; though they may have now. Ecoheat of Hebden Bridge did not reply to our request for a quote.
We also got a quotation from Sundog of Cumbria www.sundog-energy.co.uk . They are on the EST list of accredited firms. They had done the work at Dale Head on the wind turbine and I had talked to them there. We were impressed by their experience, competence and youthful enthusiasm. Their prices were little different from the others. They do not do solar thermal installations. We asked to see PV tiles and talk to the users; after 3 months we had convinced Sundog that we were serious [they have 40 enquiries for every contract successfully let] and we finally were given details of a place in Barnard Castle to visit. The users said it was trouble free, but had no records of how much electricity the tiles generated: they had inherited them on their building, which they leased. We accepted the Sundog quote for £19128 [incl. VAT at 5%] for a 2.24 KWh system of tiles to use the maximum unshaded space on the south-facing roof.
We had had Sunuser of Leeds [T 0113 262 0261] recommended for supplying solar thermal panels. They are not on the list of EST accredited firms, but the possible grant for solar thermal was only £400 and the lack of such a sum was not significant. We asked to see some of their work; someone in Baildon showed us what they had done 5 years ago; she was perfectly satisfied. Unlike Sundog, who only wanted photos and drawings, they sent an informed Sales Rep.; he was never pushy. We accepted their quote of £7812 [incl. VAT at 5%].
We agreed that the south facing roof would take the PV tiles, since they need all the sun they can get; any shadow on any part reduces their efficiency. The solar thermal panels were arranged for the garage: two on the east facing and three on the west facing roofs.
With three contractors, we were expecting co-ordination problems. There were none. They all came exactly on time. Turners, the roofers, had to put on counter battens under the PV tiles to raise them a little to help dissipate the extra heat generated. Sundog had to arrive when the south facing roof was exposed; they did. Sunuser had to arrive when the garage's east and west facing roofs were finished; they did.
The PV tiles are Mini-stonewold-compatible Redland roofing/BP Solar SRT40's. Each replaces four ordinary tiles. They interlock exactly with the Mini-stonewold concrete tiles. Sadly, Redland now no longer manufacture PV tiles; other firms do so. It would seem better, however, for future purchasers to buy PV panels which can more easily be replaced than matching tiles. Our tiles generate DC current which flows down to a Fronius inverter IG20 in the garage to be made into AC current. This tells us, second by second, how much electricity we are generating: a few hundred watts during all daylight hours on a dull day; up to 2240w on a sunny day. A separate cumulative meter, Elster A110C, keeps an official record of all the electricity we produce, in order to calculate what we are to be paid. There are virtually no moving parts and a service contract is not necessary. Once the system is in place, an electrician has to come to link it into the main electrical system of the house and the grid. [His bill was £228] The grid operators have to be informed; they own the mains cabling system and need to know that a new generating station [!] is supplying current. In this area the usual one is NEDL/YEDL T. 0845 6024453.
The solar thermal panels are filled with pressurised antifreeze which is circulated by pumps positioned in our airing cupboard next to the hot water tank. There is also a pressure gauge, and a bigger tank than is normal in order to accommodate the pipe coil for the solar thermal heated water as well as that from the gas boiler. Moreover, the bigger tank stores a lot of warmed water which can be heated up very quickly by the gas boiler if necessary. In the loft is a small spherical expansion container to take up any excess pressure. As, all the year, water is partially pre-heated by the sun, our gas boiler does not have to work so hard or for so long. In the garage is a very useful meter which shows how much heat each of the west and east panels is producing, what the temperature is at the top and at the bottom of the hot water tank, and how many hours of solar gain there has been on the solar thermal panels. We can see at a glance if we need more hot water to take a bath. 50 degrees C at the top of the tank is enough, we find.
5.1 Normally nothing needs to be done to either system. Neither should ever be turned off. All the systems are actuated by daylight, not sunlight; but they are far more productive when the sun is shining.
5.2 The weight of the heavier tank on the plinth in the airing cupboard meant that the wooden plinth on which the former tank stood needed to be strengthened.
5.3 On the PV system there seems to be no important problem. At night the grid supplies all our electricity; the grid acts as a battery for us.
COSTS AND BENEFITS
'Economy' meant originally 'management of the home or the environment'. It did not simply concern money. By this definition, the systems are very economical, saving emissions of probably more than 600 kg of CO 2 a year.
6.1.1 We used an average of 2572 kWh of electricity from the grid per year June 2004 to June 2007. We generated 1837 kWh from our PV tiles June 2007-June 2008, although the tiles were not installed until July 2007. From July 18 2008 to July 17 2009 we generated 1825kWh. Thus on average about 72% of our annual electricity was home-generated in 2007-9. From 1 October 2008 to 30 September 2009 we generated 1908 kWh, that is, 74% of our historical annual consumption. It is worth noting that we generate electricity every day of the year: PV works by daylight, not just direct sunlight.
6.1.2 We use very little gas from May 1 to September 30: the gas boiler is actuated occasionally for 10 minutes a day, if too little hot water has been provided by the solar thermal system on a very cloudy day. When we turn the gas boiler on, the temperature of this pre-heated water rises by nearly 1 degree C per minute. From October to April we turn the hot water boiler on for 10 minutes every day. The solar thermal system does not, however, supply any hot water for central heating. Before we had solar thermal panels, our average usage of gas June 2004 to June 2007 was 12,928 kWh. From September 2007 to September 2008 it was 11,086 kWh, a 1842 kWh reduction. From July 18 2008 to July 17 2009 we used 10 472 kWh even though the winter of 2008-9 was colder than usual. It is in the summer that major gas savings are made: gas used from April to September 2007, for example, was 2724 kWh, but only 1227 kWh from April to September 2008; thus 1497 kWh was saved in the summer time. We have transferred our gas account to Good Energy who pays us for renewably heating our hot water from the Governments HOTROCS scheme. Their price per kWh is higher than average, but the amount they pay us brings our costs down to the average price for gas.
6.2 In money terms, the situation is more complex. The capital value of our house is, according our insurers, increased by the total cost of purchase. Since we had a £2500 grant, we have gained! And we are certainly saving revenue money; the income from our own electricity generation can be seen as interest on the capital we have invested. It is about 1% p.a. Unlike when capital is invested in, say, a conservatory, we receive increasing income year by year.
6.2.1 All the electricity we use is measured by our main house electricity meter, and our account with Good Energy, our generating firm, is debited with the cost of using this power. We use electricity for cooking. The electricity we generate is measured by a new separate cumulative meter and our account with Good Energy is credited twice a year with 15p for every kWh we produce - even if we have used the power ourselves. When we started in 2007, this figure was 4.5 p per kWh; so it has more than doubled since then! In 2007-8 we earned £153.54. From April 2010 Feed-in Tariffs [FITS] will be introduced by Government fiat: PV generators will be paid at least 35p per kWh. This is funded from the Government's Renewable Obligation Certificates [ROCs] held by Good Energy www.good-energy.co.uk . 'Good Energy' have topped the ethical lists for moral firms and have been open with us; but their domestic electricity costs 5.7% per kWh more than the average in 2009, since it is all generated by renewables. We are officially the 'John D Anderson Solar' generating station!
6.2.2 Gas and electricity prices will go up - and up; as they do so, our system becomes more and more cost effective.
Moreover, the value of our house is increasingly enhanced, since the Home Owners Information Packs now must include details about energy performance. All house adverts now carry graphs showing its Energy Efficiency Rating and its Environmental Impact [CO 2 ] rating. Both Maxwells and Dacres Estate Agents in Baildon have said that they cannot yet estimate the extra value that solar panels and tiles put onto the price of a house since 'there is no demand': the systems are so new that they need to wait until we can show cost savings etc. The systems should be effective for 25 years, but no one knows how much longer than this they may last, since none has been installed that long.
The energy pay-back time is eighteen months for PV tiles: this figure is from an independent German PV expert who came specifically to view our tiles. This represents the energy taken to manufacture the panels calculated against the energy generated by the installation. Solar installations therefore save much more C0 2 than is needed to manufacture them. This is important for combating global heating.
Other energy generating firms pay back different amounts for renewable energy production. In Germany domestic producers are guaranteed four times the standard rate per kWh for 20 years, which dramatically changes the financial basis of all these arrangements. In Germany we would never have to pay an electricity bill!
The Low Carbon Buildings Programme offers grants on the conditions outlined above. We have received £2500 towards the cost of the PV array. I applied electronically at 0900 on the day the grants were offered; by 0930 I had confirmation of the grant.
The Ecology Building Society [and presumably others] would consider lending the money for solar installations as part of a secured loan; i.e. they would treat it as a mortgage, or part of a mortgage, and hold the deeds of the house until the loan was repaid.
We have become more attuned to nature: we notice and care more how much the sun is out; we notice and care more how much electricity we are using. This valuing of natural processes is in the long run perhaps the most important result of installing solar systems.
We feel that there should be as many electricity generating stations as possible: PV, wind, tidal and wave. These will distribute both electrical and, by extension, political, power more democratically. On a big enough scale, renewable generators can lead to the phasing out of all generating stations powered temporarily and dangerously by fossil fuels. Each station, linked by the grid, will back up the others. We could have a truly national electricity supply.
John D Anderson. <email@example.com>