Renewable Heat Incentive.

[harry]

Rep turned up today to see about fitting evacuated tube solar water heater. All more or less as I thought. You get a =A3300 grant/subsidy and =A30.17/Kwh assessed for seven years. It is assessed on the floor area of the house. The latter to start next year.

He had an electric car. (Nissan Leaf) He has a 10Kwp PV panel at home and they have a 25Kwp panel at work. 25Kw is enough to charge the car even when it's cloudy. I had a ride in it. It was as as quite as a limo with lots of sound proofing. Very fast up hills and amazing acceleration.

[Dave Liquorice]

Might start. The RHI scheme has been in and out of consultation, going t= o start, delayed and otherwise generaly messed about with for about 4 year= s maybe longer. I'll believe it when I see it...

I can't quite see how floor area has much to to do with solar thermal hotwater. The heat input is goverened by the collector surface area not =

by how much floor the building has... Floor area would be slightly bette= r for space heating assement.

[The Natural Philosopher]

Harry. That wasn't a rep. that was you We all know you are a solar panel salesman.

[BruceB]

It is because with the RHI (for heat pumps, solar thermal etc) they have the choice of making a payment based on metering the heat output or based on deemed output. With commercial RHI they went for metering. With domestic RHI I think they are going to opt for a deemed output. That output will be based on a well insulated house so by factoring in floor area and an assumed well insulated house to a SAP calculation you can come to a space heating and domestic hot water annual heat load.

[Dave Liquorice]

I still don't see anything but the loosest connection between floor area and hot water load and the load isn't all that relevant either. A correctly installed and sized system will only very rarely stagnate so the heat produced is directly related to the collector area/effciency and latitude of the installation. These figures are all well known.

Mind you if they do go for floor area I could be quids in as the floor area that the thermal store serves with hotwater (and space heating) is quite large.

[Chris J Dixon]

AIUI, the calculation is intended to ensure that the scheme does not end up paying out for equipment which has a heat production capacity out of proportion to the requirements of the building to which it is fitted. A rather broad brush approach.

Chris

[harry]

Well, that's the way it's to be done. At the moment anyway. It's the government, it doesn't have to be logical.

The heat collected/needed is governed by the usage/number of people in the house/how often they bath etc. Which turn governs the size of the DHW store. The collector has to be sized so that it works in bad weather as well as good. So in bad weather it will be working all the time. In good weather only some of the time.

There are a few control issues I hadn't thought about as well, re water temperature in the manifold on the roof on shutdown.

[harry]

True. But you might have one person living in a large house.

You have to have a certain level of insulation before you can get the RHI. However I am well over that level.

[Dave Liquorice]

That makes sense the meters aren't cheap and some one has to read them and the readings checked for fraud if you let the householder do it.

Exactly or a large family in a small one. As I said a correctly sized and installed system the panel performance, site latitude and average insolation for that area will give a fairly accurate annual heat output. Far better than using floor area. As I said this place has a much higher floor area than one would expect.

If I get bored I might look at the consultation document again.

[Dave Liquorice]

And one that misses. Anyway the system also has to be installed to MCS standards which should ensure that it is correctly sized for the hot water demand. My solar thermal system MCS certificate has an "Estimated annual generation" field what's the point of that if they don't use it? As an annual estimate it seems about right for a 30 tube collector.

[Brian Gaff]

Probably a range like that of 10 miles though!

Brian

[Bob Minchin]

Any chance of getting a diy install MCS approved though? I'm planning to install a solar thermal system and new boiler etc next year but plan to DIY and just get the boiler commissioned by a gas safe chap. Bet I can't get an MCS cert too!

Bob

[Onetap]

The manufacturer's guarantee on the batteries is how long? How much do replacement batteries cost?

[harry]

__ ___________________________________

Not at all. We went down the other side of the hill and about three quarters of the power used was recovered and put back into the battery by regeneration. The battery is only there to make up the losses in the motor/generator plus frictiona/drag losses.. It is only 18Kwh.

[harry]

No. But you could become a MCS registered installer, dunno how much it costs.But they have to have their work inspected and go on courses etc. so not cheap I imagine.

[harry]

Battery life is 8-10 years depending on how you look after in (Average mileage) Rapid charging, leaving discharged and "topping up before 80% discaharged" reduces life. New battery around =A38000 but prices expected to fall. Battery guaranteed for five years I think.

[John Williamson]

___________________________________

Errmmmm....

Nissan say the Leaf is 100% electric, no fossil fuel motor at all, not even a range extender.

Unless their website and "What Car" are both lying, of course.

[metric_trade]

If transmission losses are around 20 to 30% each way, round-trip efficiency is

50 to 65%. Are there online references to regeneration efficiency for the Leaf?

[The Natural Philosopher]

No, harry is lying as usual. Its not worth pointing it our by and large, you just take it as read that anything harry the solar panel salesman says, is a simple lie.

[John Williamson]

I suppose you could always fit a portable generator in the boot, and cut a hole for the exhaust. :-)