@derek-m Thanks again - and I agree with you. This is a voyage of discovery for me but your earlier assessment to keep the solar diverter makes sense (and anyway it’s a sunk cost). Last year, which we know was exceptional, meant I rarely heated my water with gas for many months. The diverter was effective. I will keep it and see how we get on with all of the components. I’ll know more after the 15th April when the install should be completed. And commissioned. And working as hoped.

@derek-m I haven’t looked into this very deeply yet but have an Eddi which has 2 CT clamps connected to my PV and Powerwall set up. I read that I may need to incorporate a third CT clamp to fully utilise the logic so that the Eddi sees to it that the battery is not used to supply energy instead of the PV source. I note that my Eddi does not normally start supplying ‘green’ energy from PV until the Powerwall has charged to 99% and should the sun become shy, stops taking anything from the battery below 98%. I have 8.1 kWp of PV but have only had this since mid August last year; the best I have seen so far has been in the last week and the peak was 6.7 kWp on the 25th. just for a minute or less 🙂 Regards, Toodles

@davesoa they do all work nicely together.

example: today, my powerwall charged to 100% from grid by 0530 (intelligent octopus end time). the heat pump heated the downstairs to 21C starting at 0430, pulling most of the electricity it needed to get up to temperature by 0530 at the cheap rate. bedrooms started heating at 0630 on the programmable TRV's. this used electricity stored in the battery to power the heatpump but not much because most of the house and the water in the circuit already up to temp.

rest of the day, there's been 35kwh of PV (from an 11.2 kwP array) which has gone into

3kwh into the ASHP (its been quite warm) .

(ASHP also took  4kwh from grid before sunrise)

15wh via the zappi into the car

4kwh via the eddi into heating the cylinder which is at the end of the day now reached the max immersion temp (70C) -  so next reheat will be needed later

and the rest into the powerwall for use this evening.

In these shoulder seasons you can run almost all of it based on either cheap rate (TOU) or free (PV) - YMMV based on the relative sizes of PV , battery storage and car mileage of course.

@iancalderbank I have PV envy. 😀 Yours is bigger than mine by a factor of 3. And I can’t use Intelligent Octopus until Myenergi/Octopus work out an integration so will stay with Go for now. On the upside all my consumption is at TOU rates. Other than that it all sounds very positive. I guess with an April install it will be a while until I will fully know how the ASHP works - and what it costs.

Fascinating read everyone, thank you.  We are due to get our PV and battery install carried out next month.   I have been looking into Eddi to further limit the power exported.  I’ll be monitoring this thread in the coming weeks.  

atb. 

Drew

Mid gardening session today, with no access to my computer, I realised that I need to retract my earlier statement. 

On a sunny day (and this will depend on the size of the PV array), the excess solar will fill the battery first. Once the battery is full, it will then heat hot water via the power diverter. So they can all play together. 

We have 3.6kWh solar + battery, 10kW ASHP & IBoost. All works beautifully for us.

Solar PV powers, in order; ASHP when running, surplus generation to battery to charge to full, then to IBoost, then to export at 15p/kWh. Most days the ASHP fulfils our HW to 50degC on timed boost, iBoost will raise it up to 55degC+ with any excess power, and thereby run the anti-Legionalla.

IBoost and Inverter (Growatt SPH5000) have never been in conflict, Inverter is far more sensitive and reactive than the iBoost, so sends the power to where it is needed. Never had the iBoost on discharging the battery.

In the heating season we export very little, only towards the end of a really sunny day when all demand is satisfied. In the summer months we'll export more, and the IBoost will charge the water before the ASHP timed daily 1-2pm charge up. If the cylinder stat is fulfilled via IBoost at 50degC, the ASHP will simply not come on. I may well switch the ASHP off in summer and simply use the IBoost.

Impressed at how it all hangs together 🙂

@allyfish Pleased to hear that it is all ‘hanging together’ as you detailed allyfish. As I have a Sunamp Thermino, I am able to charge anytime of the day or night when cheapest if there is little or no sunshine for the PV route to take care of things. The insulation is very good and any losses (no more than 0.75 kW/h per day) are used in the airing cupboard anyway. I am being as scrooge like as possible and having checked the Octopus Energy Agile rates, then tell Eddi to only use if less than x pence per kW/h. 😉 Regards, Toodles.

@allyfish That’s really encouraging to hear. Your system is almost identical to the one we will have (12kWh HP) and a slightly bigger battery. Even today, with all the rain, the iBoost was heating the water after the battery was fully charged.