PV Panels, FITs and EPCs

[worms]

Looking into photo-voltaic panels at the moment and only just found out that you only get the full feed in tariff if you can produce a household energy performance certificate showing a grade D or above.

Any idea how easy that is likely to be to achieve? House is single-storey, rubble-construction and gyproc, single-glazed, 3-bedroom, single layer of rock-wool loft insulation (but could do with more) and currently uses 950kWh electricity per annum and roughly 3,000 litres of oil.

How high a hurdle is grade D?

 

[MdB]

You can download SAP calculation software to work out what you need to do. I used sapper http://www.rusfa.com/downloads.htm but be prepared to put in quite a lot of effort to understand it and work out how to use it. It isn't the best bit of software ever - but it is free for evaluation.

My house started out as a band F (3 out of 100) and should end up around band C/D (71 out of 100). This involved changing to a heat pump, insulating properly (100mm celotex) the floors and walls and roof (600mm rockwool equivalent). According to the calcs, the remaining heatloss is split 30% our two old stone walls (uninsulated), 30% windows (poor quality double glazing) and 40% everything else which is insulated.

The heatpump makes the biggest difference in rating as it reduces your fuel usage by a factor of 4 or so (losses in generating electricity doesn't count - which is arguable). Without that, you will need modern double glazing and good insulation in everything including floors. As above, miss a couple of walls (25% of our house??) and the heat wastage is high.

I would also say that as you have missed the boat on the best grants, PV isn't really justified financially unless you know you are going to stay in the house for at least the next 5 years - preferably 10 - I looked into the sums recently. It is doubtful as a green technology also - there is better.

 

[Flyfisher]

As an aside, I can't really understand why FITs should be linked to the energy efficiency of a home. Surely solar PV is a good thing in all cases?

But my real question is about that 950 kWh per year figure. Is that really correct? It's only 2.6 kWh per day and, at a rough cost of 12p per unit, would give you an annual electricity bill of £114.

 

[worms]

As an aside, I can't really understand why FITs should be linked to the energy efficiency of a home. Surely solar PV is a good thing in all cases?

But my real question is about that 950 kWh per year figure. Is that really correct? It's only 2.6 kWh per day and, at a rough cost of 12p per unit, would give you an annual electricity bill of £114.

Well spotted! That should have been 5950 kWh! (Dodgy keyboard is my excuse!) I quite agree that the logic of linking FIT rates to EPC escapes me. I guess, though, it would encourage me to invest first in energy efficiency rather than generating capacity, which may be what the Gov't would rather I do and indeed may be where I end up!

However with 2kW pv systems now around the £3k mark, electricity prices rising rapidly each year and the FIT rate dropping each quarter, I do fear that I will miss the boat if I wait till I get all the energy efficiency side of things sufficiently sorted!

 

[worms]

You can download SAP calculation software to work out what you need to do.
I would also say that as you have missed the boat on the best grants, PV isn't really justified financially unless you know you are going to stay in the house for at least the next 5 years - preferably 10 - I looked into the sums recently. It is doubtful as a green technology also - there is better.

MdB, thanks, I'll try that software when I have longer to work it all out. I agree that solar pv is perhaps not the best of the available options, but it is the easiest option at present. A 2kW wind turbine would probably work here and give me a greater output, but would cost much more and come with greater hurdles.

Perversely, I think I would rather there were no FITs as it skews things and gets in the way of a detached rational approach to the issue.

 

[MdB]

Perversely, I think I would rather there were no FITs as it skews things and gets in the way of a detached rational approach to the issue.

I agree though do see the point in helping get new tech off the ground by creating a market - be it artificial. Solar PV is improving all the time and I can see it becoming a very valid for of energy generation - it just isn't there yet. I've said it before and I'd love to be proved wrong but I have yet to hear of a solar PV factory that uses its own products to generate the energy it uses during manufacture.

 

[plasticpigeon]

Why are these semiconductor things suddenly photovoltaics and not solar panels?

 

[worms]

Why are these semiconductor things suddenly photovoltaics and not solar panels?

I guess because the term "solar panel" doesn't differentiate between something that directly generates electricity from the sun's light energy, something that collects heat from the sun, a mirror array to concentrate the sun's energy in one spot, or a fancy sort of window that makes best use of the available light - all are sometimes described as solar panels!

 

[worms]

Perversely, I think I would rather there were no FITs as it skews things and gets in the way of a detached rational approach to the issue.

I agree though do see the point in helping get new tech off the ground by creating a market - be it artificial..

Perhaps we have reached that point - if the double glazing salesmen are now on the pv bandwagon (and even without FITs pay back is faster than for DG), then QED for market creation! I'm not sure I can see the panel prices dropping much more, so I would argue we are moving into the mature market phase.

As an aside, I am concerned about the increasing loss of tree cover as people remove all the trees to the south of their properties!

 

[biffvernon]

As an aside, I can't really understand why FITs should be linked to the energy efficiency of a home. Surely solar PV is a good thing in all cases?

Indeed. I've come to the general conclusion that we have a government (and civil service) that doesn't really believe in science.

 

[biffvernon]

As an aside, I am concerned about the increasing loss of tree cover as people remove all the trees to the south of their properties!

We cut the top 20 feet off a couple of 50 foot leylandii trees when we fitted our pv system.

 

[biffvernon]

Perversely, I think I would rather there were no FITs as it skews things and gets in the way of a detached rational approach to the issue.

It's a product of the failure of the free market to factor into the cost of fossil fuels a new planet. Environmental costs are treated as externalities.

 

[Flyfisher]

NASA has the 'new planet' thing under control. Curiosity is now trundling around on Mars supposedly looking for past signs of life there, though I reckon it's looking for fossil fuels. We can then establish a base there and burn loads of Martian oil/coal/gas as part of a terra-forming project to heat the planet sufficiently for us to move in. After all, we've changed our own climate over the past hundred years or so, so it shouldn't be too difficult to do the same to another planet. :wink: :lol:

 

[angrybird]

I know PV panels are supposed to save us energy and money but personally I would never have them near my house!imo its a bit like putting the Mona Lisa in a hoody and Reebok trainers!
and ....is it false economy? how much does it cost to manufacture these and what damage is the manufacturing process doing to the environment?
These are up on my top ten hates along with UPVC windows :evil:

 

[plasticpigeon]

I don't think out weather allows us to get the best from solar panels. I've read a paper that looked at the "well to wheel" type energy balance for solar panel and in the UK they have a very long payback time. I can't remember specifics though.

There is an interesting company called Oxford photovoltaics that are developing transparent solar panels that look like coloured glass which would at least mean it could be used in windows instead of being stuck on the roof in an incongruous way. I have a feeling they are also trying to use more abundant materials in their manufacture.

I've done a small amount of work on solar panel array optimisation. It is surprising how much more efficient the arrays could be if they had some sort of strategic control.

 

[biffvernon]

I know PV panels are supposed to save us energy and money but personally I would never have them near my house!imo its a bit like putting the Mona Lisa in a hoody and Reebok trainers!
and ....is it false economy? how much does it cost to manufacture these and what damage is the manufacturing process doing to the environment?
These are up on my top ten hates along with UPVC windows :evil:

I know a couple of people with listed properties who have put their pv systems either on the ground or on an outhouse without a pretty roof. My own roof was particularly undistinguished with concrete tiles. We chose not to use the outhouse roof with old pantiles. That would have been a shame.

Is it a false economy? How do you measure such things. I make money out of mine. The energy payback time is just a couple of years and they should last 30. All manufacturing has an environmental cost so you have to ask is it less than that of the alternative ways of generating electricity - worse than wind in the British Isles but definitely better than all the fossil fuels.