This post has been moved to a page on lighting.
The tariff for a small domestic solar installation will be 16p per kilowatt hour, down from 21p, and will decrease on a three-month basis thereafter, with pauses if the market slows. All tariffs will continue to be index-linked in line with the retail price index (RPI) and the export tariff will be increased from 3.2p to 4.5p. The new tariffs are expected to give a return on investment (ROIs) of more than 6 percent for most installations, and up to 8 percent for the larger bands.
The scheme lifetime will be reduced from 25 years to 20 years for new solar installations.
- Tariffs for solar PV installations from 1 August to be 16p/kWh for household scale solar PV installations. Tariffs for larger installations are also to be reduced
- Multi installation tariff will be increased to 90 percent of standard tariff. Organisations with more than 25 PV installations will get 90 percent of the standard applicable tariff, increased from 80 percent
- Average tariff reductions of 3.5 percent every three months. Reductions will be bigger (up to 28 percent) if there is rapid uptake.
- Tariff cuts will be skipped (for up to two quarters) if uptake is low. Uptake in three different bands (domestic (size 0-10kW), small commercial (10-50kW) and large commercial (above 50kW and standalone installations) will determine the quarterly reductions within those bands.
At yesterdays Green Building Event at the Eden Project the news came through (Tweet feeds) that Greg Barker, the UK government energy and climate change secretary tweeted:
“Having listened carefully to industry, we are looking at scope for pushing back a little the next proposed reduction in the solar tariffs.”
They were due to be cut in July from the current 21p per Kw.
If you have / get solar panels there are several return on investment streams:
- Generation tariff – your energy supplier will pay you a set rate for each unit (or kWh) of electricity you generate. Once your system has been registered, the tariff levels are guaranteed for the period of the tariff (up to 25 years) and are index-linked. For a full list of generation tariffs, see FIT payment rates published by Ofgem
- Export tariff – you will get a further 3.2p/kWh from your energy supplier for each unit you export back to the electricity grid, so you can sell any electricity you generate but don’t use yourself. This rate is the same for all technologies. At some stage smart meters will be installed to measure what you export, but until then it is estimated as being 50% of the electricity you generate (so that if your solar PV system is less than 30kWp you do not need to have an export meter fitted)
- Energy bill savings – you will be making savings on your electricity bills , because generating electricity to power your appliances means you don’t have to buy as much electricity from your energy supplier. The amount you save will vary depending how much of the electricity you use on site.
One of the Eden Project show talks had these figures, that may be high end in terms of them being from a chap that is from a PV installation company.
The Energy Saving Trust has figures of:
A typical domestic solar electricity system with an installation size of 3kWp could earn:
- £530 a year from the Generation Tariff
- £40 a year from the Export Tariff
- £100 a year reduction of current electricity bills
Scaling this up to a 4kWp system that’d be £893.
Being fair to Tony at Cornwall Solar Panels (Tel 01872 562 775) who gave the above figures, his entire talk was centred around there being no such thing as the best solar panel, but the best solar panel configuration for a particular situation. Panel efficiency, shape, size, drop off with heat, drop off with shading, the roof angle and a bunch of other variables (string or per panel inverters) all influence the efficiency and the system cost and so the Return On Investment (ROI). His talk went over about a dozen different installations they’ve done and have figures from. The clear implication / impression is that they are doing installations all over Cornwall.
Siemens have recently brought out a miracle A+++ fridge; the KG36EAW40. It has the best energy rating on the market right now. Annually it costs you £18 a year to run, compared to a more modest A rated model, which costs you approximately £51. That’s a saving of £33.
Get a frost free freezer
Don’t leave cooking appliances such as your microwave on standby. It wastes approximately 7kW of energy per day – annually that’s a huge £84 per appliance.
An induction hob is the most efficient hob you can get: it’s 90% more efficient than gas or electric, mainly because the hob only heats up when it recognises the pan so no energy is wasted when the pan isn’t present.
Another good tip is to use halogen lighting in your oven as they’re 20% more efficient and 36% brighter than standard light.
The Bosch Logixx WAS32461GB washing machine, which has a function that measures the exact amount of water needed depending on the weight of your wash. It means you won’t waste any extra water or energy to get the load washed. It’ll only cost you £22.68 a year to run, which is minuscule compared to other machines.
There may be a problem with the current Silver Spray plans and the angles for the solar panels. The current plan is for the panels to be bolted onto the proposed flat roof at the back.
- Solar panels should be south facing and between 20 and 60 degrees.
- I’ve heard / read that the ideal angle for solar panels in Cornwall is for them to be at 30 degrees (and south facing).
- Below 20 degrees panels don’t self-clean when it rains. Dirty panels are less efficient
- The angle that solar panels are normally mounted on flat roofs is usually low to reduce the amout they can get grabbed by the wind and ripped off the roof !
- It could just be that a framework for the panels is factored into the building so that there is no chance it can be ripped off by the wind.
- Flat roof mounting systems for panels all seem to be at about 10 degrees, so that the gap between panels is around 38 cm, and so that their is reduced possible “wind load”
- Current rear flat roof area is about 4.1 x 8m = approx 32.8 sq m. If panels are all flat, a 4kW system takes about 28 sq m. So will need to see how the space works out.
- See http://www.bauder.co.uk/photovoltaics-and-rooflights/photovoltaic-energy/baudersolar/pv-modules – images below – gap between panels moves up to 1.36m from 0.38m as solar panel angle of tilt changes from 10 to 30 degrees. But see reasons below for wanting 20 degrees or more tilt.
- The Energy Saving Trust matrix for PV angle of tilt and how much south facing, that suggests optimum is south facing and between 20 and 30 degrees tilt.
- More vertical panels do better in the winter, when the sun is lower in the sky. You are more likley to want more hot water in the winter (for space heating) and more electricity generation (to power feed the air source heat pump). BUT only 10% of generation output will be in the winter, so best to angle the panels for max, over the year, output.
I ran figures through the Energy Saving Trust calculator for a few variations at the Silver Spray postcode location:
- South slope, XLarge 4Kw, 90 degrees = 2,688 kWh pa
- South slope, XLarge 4Kw, 60 degrees = 3,499 kWh pa
- South slope, XLarge 4Kw, 50 degrees = 3,643 kWh pa
- South slope, XLarge 4Kw, 40 degrees = 3,716 kWh pa
- South slope, XLarge 4Kw, 30 degrees = 3,715 kWh pa
- South slope, XLarge 4Kw, 20 degrees = 3,640 kWh pa
- South slope, XLarge 4Kw, 10 degrees = 3,492 kWh pa
- South slope, XLarge 4Kw, 0 degrees = 3,274 kWh pa
Photovoltaic Thermal:: EcoBuild Expo Update
At the Ecobuild expo, there were a LOT of companies who had photovoltaic elec or water heating systems. Few were combined PVT (both electricity and heating water). So I started asking why. Speaking to those that make the panesl and installers / advisors the consistent reply was that the reduction in output of both systems was more than 50% down on what you’d get if each was stand alone. One company that produced PV and PT panels said that:
- A PV panel could produce around 280 Watts of elec, a PVT panel about 120 Watts
- A PT panel over 200 (I think degrees) water, but only 40 degrees from PVT.
Yes, it’s still good to cool down PV panels, with ventilation, or even surrounding green roofing. But it seems that cooling them, by linking in pipes to generate hot water doesn’t work. It seems that the temp hot water panels work at is so high to be efficient, that takes out too much electricity production. Or you compromise the amount of hot water production by having the panels at a much lower temp. ie to be efficient they both operate at vastly different temperatures.
So that means looking at seperate systems for electricity production (PV), hot water productin (PT) and something for when the sun isn’t shining for hot water (for taps and heating).
- The debate re PVT versus PV or PT is extensivly thrashed out at http://www.greenbuildingforum.co.uk/forum114/comments.php?DiscussionID=7740&page=1 (the debate rapidly moves on from Thermodynamic Panels.)
Thanks to Simon, I ended up at a great evening at the Eden Project on Wednesday. It was run by the Cornwall Sustainable Building Trust. Some great speakers including Charlie Luxton who covered a lot of items I already knew about (it’s always great to get confirmation from somebody with heaps more experience than yourself thought !), and quite a few I didn’t.
Warm Water into your Washing Machine
For instance, modern washing machines have a single water inlet, for cold water. But what this means is that these modern washing machines are using electricity to heat the water to the desired temp for the selected wash. Eeeeek, we all know that due to (not only) transmission from power stations for most people, the efficiency of heating water by electricity is shocking (see figures below *).
How about making sure that there are mixer taps to give warm water eg 20 degrees into the back of your washing machine.
- Central heating tends to run at 55 to 65 degrees C.
- Under floor heating runs at around 45 degrees C.
- A bath is going to be, 44 to 46 (a VERY hot bath) degrees C.
- BUT need to occasionally boost the water in the tank to kill legionella:
– 66°C Legionella die within 2 minutes
– 60°C Legionella die within 32 minutes
– 55°C Legionella die within 5 to 6 hours
He also mentioned that instead of cement (environmentally horrible stuff) go for GGBS +/or fly ash cement. It seems these are cements made up from the by products of already in place (and here to stay for a while) industries such as blast furnaces and coal burning.
* Energy and Electricity
These figures are taken from an eco building book, the Green Building Bible (Volume 1):
- 100 units of energy in fossil fuel into a typical UK power station, gives
- 38.5 units of energy into the grid, of which a further 3.5 units are lost on transmission & distribution, so you only get
- 35 units to a house, of which 13 lost through inefficient use
So 100 becomes 22 (or 35 if you have 100% efficient use, through good appliances, voltage regulation etc.)