Renewable Heating Incentive proposals - a guide for domestic solar water heating

Gavin A · Sep 21, 2012

I know it's not electrician specific, but there are enough solar installers on here who also do solar water heating systems, so here's a quick guide I've worked up for the implications of yesterdays 110 page RHI consulation specifically for solar water heating systems.

RHI guide for solar water heating systems

here's the first few bits from it.

RHI for Solar Water Heating systems proposals

Legacy systems (systems installed since 15th July 2009)

In line with the previous plans, all MCS certified solar water heating systems installed since 15th July 2009 should still be eligible for RHI payments once the scheme starts to operate.

How will payments be calculated?

Payments should be based on the original SAP estimates of output from the systems, with no requirement to meter the actual heat output.

What rate will solar water heating payments be made at?

17.3p per kWh of heat generated is the proposed rate to be paid for solar water heating systems.

How long will the payments run for?

7 years is the proposed payment period for solar water heating under RHI.

It's unclear if this is from the start date of the RHI scheme, or the installation date for legacy systems.

solarfred · Sep 21, 2012

So no need to have a heat meter? I have not read the whole document but this was an important criteria I thought? Has it been totally dropped or just for prior installs?

Gavin A · Sep 21, 2012

totally dropped for solar water heating it seems, though there may be the potential for it to be fitted as an option, or not.... depends on the consultation, I think I'd like to have the option, as it encourages higher performance systems instead of systems with just the bear minimum of pipe insulation etc.

Less clear for heat pumps etc but the intention definitely seems to have moved back to using RDSAP or some other method - they've actually passed the buck to MCS, so who knows what they'll come up with on that score.

It seems the metering trials haven't been the overwhelming success decc imagined they would be. Funny that, given that the heat capacity of the solar fluid depends a lot on its glycol concentration, and whether the flow and return temperature is measured within the pipe or via an external stat etc.

solarfred · Sep 21, 2012

Spent time and money trying to secure approved metering with Glycol element for MID approval but once again the government has had me on a wild goose chase. Have they any idea how much time and money is being wasted to try and comply with planned regulations. Jeeez!

Worcester · Sep 22, 2012

@Gavin A
If the customer wants to get the RHI it looks like you need to be a Green Deal Assesor to supply / install Solar Thermal, - from the consultation document:

Consumers would need to have installed those thermal energy efficiency measures identified as ‘green ticks’ through the Green Deal assessment process.

Gavin A · Sep 22, 2012

I read that, but AFAIK they're also shown on the EPC now as green ticked items, so I can't see the need to get green deal stuff involved if we don't want to, just carry the measures out.

The Solar King · Sep 22, 2012

There is a great deal to digest in the consultation.
Still only skimming it. Have a look at point 160-162. This does acknowledge that solar thermal potentially needs to be treated in a different way. We need some innovative proposals on this. The STA Solar Thermal working group are already on the job.

To me the greatest weakness in the whole consultation is the continuing linkage with the ROC for offshore wind. As stated elsewhere DECC need to get their heads out of their backsides over this. It is the position of intellectual pigmies who appear to have neither the capability or motivation to grasp the implications of the opportunity to positively engage the wider community in carbon reduction, energy efficiency and renewable technology. They are not comparing apple with apples. They are not even comparing apples with elephants. The two are not comparable. The arguments are perverse and lead to totally inadequate policy outcomes as shown by the proposals in this consultation.

The new proposals given in the draft of MIS3001 for calculating the output of a solar thermal system mean a 4sqm system is likely to be rated at 2000kWh/a. This would equate to an annual payment of £346.00 or a total of £2422.00 over the life of the tariff. This represents about 55% of the capital cost of the system, hardly enough to incentivise a prospective user. Even worse, it does not even equal the equivalent of the ROC payment for offshore wind if taken over 20 years which would be £3320.00.

There is a deal of work to do to get DECC to see sense. We have to acknowledge there are budget constraints, but when you think they have been shoveling our money into the banks at an interest rate of 0.5%, shoveling it into renewables at the same rate would do far more economic good and create far more jobs.

Gavin A · Sep 22, 2012

ted's pointed out elsewhere that he thinks they're actually proposing to pay RHI for 20 years worth of heat generation, but to pay that over the first 7 years.

This does actually seem to be what they're saying (139,144 and q25), in which case the paybacks will be a lot better, but explaining how this works will be a lot harder. If this is the case, I think it also raises questions about how they treat payments already made for year 15-20 if the system gets ripped out 15 years down the lines - presumably legally this money will need to be repaid, although how they'd know isn't clear.

I had read this stuff before writing our guide, but had assumed that they'd already included these calculations in the per kWh payment figures for the proposed 7 year payback figures.

I think I'm going to seek some clarification on this tbh.

TedM · Sep 23, 2012

I agree it's really unclear and also confused by the fact that the solar tariff has now been capped (let's not even get into a discussion of the abstruse logic behind the cap) which means a comparison of the proposed 17.3p against the previously proposed 18p for 20 years is not necessarily meaningful.

The absence of a worked example in the consultation is a glaring omission - especially compared to other DECC consultations.