RHI, Solar Thermal & Swimming pools...

[Energetic]

We have a legacy ST system installed in early 2011 in a large family home comprising 120 tubes, 500L thermal store and a heat exchanger to a pool. The loop to the thermal store is metered, installed to the guidance at the time and completely separate to the pool loop yet the system is not eligible for any RHI due to a pool being in the mix.

Given that the RHI payments are deemed by the EPC which won't/can't include any pool heating why is there no provision in the RHI for DHW if a pool is involved? I understand that this may be possible in the future after amendments but not currently.

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[jason121]

My solar thermal payments were calculated from the MCS certificate.

 

[Energetic]

Interesting, my understanding is/was that it was from the EPC and that the MCS calc was noticeably higher but not valid for payments.

 

[jason121]

my ASHP payments calculated from the EPC. That is why I on here to try and make sense of it all

 

[TedM]

Solar thermal RHI is calculated from MCS024 which effectively uses SAP2012. The main basis is the m[SUP]2[/SUP] size of solar panel/tubes so any system sized to heat a pool would be over compensated against a system that was sized just for DHW demand. DECC have simply decided that metering doesn't apply in this situation.

The commercial RHI will pay for heating a pool as long as it is fully enclosed.

 

[Energetic]

I could disconnect the pool side and let the array stagnate for half the year but the array will still be huge.

The customer is likely to be pretty annoyed with this situation, it wasn't a cheap system. We stopped doing thermal shortly after when the first delays to the RHI were announced and i've still not properly looked through all the RHI stuff.

So the payments are calculated differently for the different technologies, that's handy...

What are the chances of a system such as this being admitted after an amendment do you think?

 

[The Solar King]

MCS024 is a great deal more than SAP. It takes from SAP the hot water use calculation and some of the detail of solar thermal panel performance. There is an additional panel performance and other criteria used.

It then overcomes the major failings of SAP as far as retrofit and most other situations are concerned. You have to remember SAP is designed for a specific purpose and works off floor area. From this there is an occupancy calculation that starts from a national average of 3.1 people which simply doesn't work for solar thermal. MCS024 only reverts to floor area if occupancy is unknown. The RHI and MCS standards need to take account of actual occupancy to function in terms of both system sizing and payments.

Because the MCS024 calculation method is directed at domestic hot water supply, it cannot cope with solar water heating for other purposes. It is specifically designed to avoid the need for metering.

There is a review of the RHI in the autumn where other technologies (eg PV-T) may be brought in to scope. There may be provision made for swimming pools. For the reasons given metering would have to be involved if it is included. Best thing would be to lobby for its inclusion or get your customer to do so.

 

[Worcester]

There is a review of the RHI in the autumn where other technologies (eg PV-T) may be brought in to scope. There may be provision made for swimming pools. For the reasons given metering would have to be involved if it is included. Best thing would be to lobby for its inclusion or get your customer to do so.

Metering still shouldn't be nescessary, so long as DHW is prioritised, you can still calculate the contribution to DHW even when all the excess is 'dumped' to a swimming pool.

You also have the situation wehere some manufacturers are paranoid about stagnation and always want some form of heat dump for any excess not used for DHW.

The big anomaly though is that it makes far more sense to be able to put ST into a thermal store than simply a DHW tank if you have one, yet the current RHI doesn't cope with it.