Mike Siebert calls

16 April : In my acknowledgements, I have mentioned Mike Siebert as 'sparking off the idea'. He called round this evening for a look at the system, and to extend discussion of future projects.
   It was a discussion a year ago when he mooted the idea of having pipes from a solar panel feeding into the same mass under a house as the ground loop from a GSHP.
   This is difficult to model theoretically - how big would you make a concrete slab or rock store? 300 thick? 500 thick? the size of a swimming pool? (I am sure Dr Chris Wood knows how....) would you insulate under it, or only at the sides? (letting heat escape downwards but not sideways).
   But then one thinks there would be a stasis or evaporation problem with water, and that a large block of phase change wax might do it better because it stays at one temperature.... and concrete is a CO2 producing material. In our case, if the soil is well compacted with no cavities or moving groundwater, maybe the earth is a good battery, and merely needs recharging more quickly than normal solar heat can get down there.
   After making some enquiries in the Dept and getting nowhere, it seemed to me easier to model it in full size and realtime, on my house, and as I was unsatisfied with the performance of the GSHP, I wanted to find a way to make it work better.

  Mike is presently thinking of designing a range of houses, but he is frustrated that you can't get triangular PV panels, as so many houses including the ones he wants to do have hipped roofs. He is also wondering if the sunbox idea could be applied to black roof-tiles on a roof-plane. [Actually Sharp do make triangular panels, but they are not exported to the UK and not approved for certified installations in UK]. He and I and others are also preoccupied with the idea of combining Photovoltaic and Thermal - and I am building one right now!