Discussion ... ASHP(Air/Air) with Solar pv ....

zeupater

Hi

Been dull & pretty cold here for a while now, -7C last night & the thermal mass is pretty much depleted to levels where it's starting to tell ... leaving stock of logs alone for now just in case someone pulls the plug on the grid supply for a while, so the GCH has been used to stop any further internal mass cooling and maintain comfort ... not much though, about 1.5hours on Sat followed by 0.75 on Monday & a further 1Hr yesterday, so a little over 3hrs in total ....

.... Sunny today though (although still freezing!) so at least there's some solar gain for the few hours it hits the glazing, about 1.5kW.t of thermal heating the DHW, with most of the PV generation flowing directly to the heat pump, which is currently blasting the heat out as fast as it can ... still enough electrons finding their way to the grid to help relieve the strain too ... not too many though, currently fluctuating between ~40W & 70W, but heck, I may be generous like that, but they were all mine .. mine ..mine .....

HTH - Z

zeupater

Hi

Just another general update for anyone who's interested ...

Sunny again today, PV initially hit by thick frost on the panels (-7 again at 7am this morning) so generation was poor until there was enough heat in the sun to thaw it away ....

What's been generated today has mostly been swallowed up by the heat-pump, solar gain has been pretty decent & the solar thermal's been performing quite well too, not enough to heat the cylinder, but enough to help ... it's pretty comfortable where I am at 20.5C & the heatpump is currently pulling 400W, so ~2kW.t of heat provision , but as suspected the internal thermal mass elsewhere is now depleted to an extent where any heat added is just being absorbed at a rate that makes little difference to the air temperature after a couple of hours ... if the dull spell in the past few weeks hadn't been so extended, we may not have needed to call on the GCH at all yet ...

With temperatures easing over the next few days & the end to the current cold spell forecast to be early next week, I'm not going to blast the GCH up to build the thermal storage up quite yet as raised temperatures during the exercise will simply increase int/ext heat-loss, rather I'll look to maintain everything around where it is and run the heatpump with both GCH & log-burner for a while when daytime ambient temperatures are close to, or above, 10C as opposed to current levels, so probably next Monday/Tuesday is looking good ....

HTH - Z  

#Edit - GCH 1.5Hrs yesterday, 1.75Hrs today ...

Martyn1981

Last night, heading for bed and saw the outside temp was about 10C ....... double then triple checked, Shirley not true, but it was. So popped one of the A2A units on for the night on cheap rate. Wish i had batts. 

Shortsy

I'm planning to install air to air plus solar PV to use the PV energy during the summer to run the air to air, so have found this thread very interesting. Thank you for sharing your experiences. However I'm not sure how many air to air units to go for, or what battery or heat store to specify. I e posted a couple of queries on other threads about this.