Sunday 2 March 2014

Replace or Refurbish?

What to do with older solar heating systems 

It could be so much better

I've been getting correspondence from solar installation businesses asking what the domestic RHI might mean for older solar systems, specifically ones that were never entered onto the Microgeneration Certification Scheme (MCS) when installed.  Is there any way for these to claim the Domestic Renewable Heat Incentive (RHI)?

Can you just inspect that the solar heating system is compliant with the current MCS scheme, re-commission it and register it as if you've just installed it?

Do you have to rip it out and put in a whole new one?  Would even this be allowed on the scheme?

Setting aside the fact that the intent of the dRHI was to stimulate new installations of renewable heating, and that finding a way to register an existing (and potentially working) system is not really in the spirit of things, let's have a look at the regulations and see what they have to say about it. 


A review of the MCS standards (MIS3001 and MCS 004) finds that they are silent on whether the equipment used when installing a solar system must be brand new to be registered with the scheme. The implication is therefore that an installer could go through the standard line by line to ensure that the existing installation is compliant, making changes to components as required and registering the system on the MCS database.  In effect the installer is building a system from ‘second hand’ parts, some of which happen to already be on site and fixed in place.

However, just getting MCS registered does not mean you can get the domestic RHI.  It's also necessary to comply with the eligibility requirements of the RHI scheme itself.

Domestic RHI

The domestic RHI legislation has now been laid in parliament, so it’s possible to see the basis that OFGEM will be using to create the scheme rules.

The relevant section of the domestic RHI regulations is on page 12 in section 9:

Plants used to generate heat before the first commissioning date9.—(1) The requirements referred to in regulation 3(b) are that no part of the plant which generates heat, other than any of the components listed in paragraph (2), was used before the plant’s first commissioning date.(2) The components referred to in paragraph (1) are—(a) immersion heaters and other components which solely generate heat for the purpose of heating domestic hot water;(b) supplementary electric heaters; and(c) circulation pumps.

From the above it seems that so long as the heat generating part of the installation is new, then other parts of the heating system can be re-used.  This makes sense – it would be crazy to insist that a new biomass boiler installation also had to replace all of the connecting pipes, radiators and hot water cylinder in the home.

In relation to a solar thermal system, the parts of the plant that can generate heat are:

  1. Solar Collector
  2. Pump
  3. Immersion heater in cylinder

Items 2 and 3 are specifically excluded in the regulations.  It seems to me that to modify an existing solar thermal installation so that it is eligible to join the domestic RHI scheme, it is necessary to change the solar panels, but that all other components could be re-used.

Have I missed something?