Dillsue

Fogstar have a list of inverters that are compatible with their battery kits so probably best to stick to one they know will work. Install from scratch is probably the best part of a day. With the kits you need to balance charge the cells which would take a bit of time to assemble and disassemble. Charging may take a few hours or maybe days. This is all on their Web site. For install you got the following to do- Batteries need assembling into the pack enclosure Battery pack DC cabling needs connecting to the inverter together with a Canbus comms cable Mount inverter and connect up AC connection to consumer unit Connect up solar if its a hybrid inverter Install meter/CT by service meter and connect up supply to the meter Run comms cable between inverter and meter If you're going for an inverter with a backup output for when the grid goes down you've got to install another consumer unit and move the backed up circuits over to the backup CU. Then run a supply cable between the inverter and the new CU. Could be best part of a day just for the backup CU!

Don't spend too much time recrunching as summers only just round the corner and PV£ will be slipping through your fingers😁

If the cable was correctly sized to carry 7 kw from the house to the garage for the charger then it will be large enough to carry up to 7kw in the other direction ie from the battery inverter to the house. FIT rules changed a few years ago and you can chop and change a system like adding batteries and probably change the inverter for a hybrid if that suited you better

This https://www.fogstar.co.uk/collections/solar-battery-storage/products/seplos-v4-kit-and-x16-highstar-314ah-bundle

If your existing solar inverter is a hybrid version then you can connect batteries to that, but..... if you want the batteries remote from the inverter then you'll need massive cables to carry the high current delivered by the battery if its a low voltage battery, around 48/50volts. If you want the batteries in your garage the probably more cost effective to have a second inverter in the garage to manage the batteries

Fogstar do 15kwh self assembly kits for £1480 so under £3k for 30kwh and showing in stock. How much money you can generate depends on so many things but you'd need to estimate usage and choose a tariff as a start

What would those same comparative figures be for a more normal winter time of say 7 degrees with a load on both pumps of 3kw?

Isn't plastic conduit used for mech protection?? Ive no idea, but do the regs specifically say metallic protection??

Put a duct in so you can easily change the cable if needed?? I don't know what the regs say but with a duct run to a "safe" area either end you may be able to run singles in the duct which will be way cheaper than an equivalent SWA.

OK, but that's the shower that may need a pump, not a vented cylinder. We're open vented for CH and DHW and have a pump only on an indulgent en suite shower. Rest of house incl a second first floor shower isn't pumped.

Our house has a calculated heat loss of 8.5 kw at -2 but we put in a 7kw HP on the basis that it would be more efficient as the days of sub zero temps are few and far between and we could always run a fan heater or switch over to an LPG boiler if the HP couldn't cope. The HP has done 100% of the space heating since september and through the few cold snaps we've had recently with temps getting down to a degree or 2 below freezing. It worked very hard and guzzled eleccy whilst it was freezing but I'm hoping that the undersizing will pay efficiency dividends for the rest of the year?? An MCS umbrella/HP supplier wanted to sell us a 12kw unit!!

Why do vented cylinders need pumps? Other than the circulator in the boiler/HP there's no additional pump needed because the cylinder is vented??

Yes, assuming you'd charged the battery from solar. If you've charged the battery from grid eleccy then you need to deduct the unit cost of the energy in the battery from the import your offsetting or the 15p export rate. When weighing all this up don't forget that when the ASHP is using the most energy in winter your solar will be generating at its lowest. Unless you've got a massive array its likely your solar will make only a negligible saving on your ASHP running costs. PVGIS will give you a monthly forecast so you can see what you're likely to generate in the winter and compare it to forecast ASHP demand.

I'm not certain on this but there was a long discussion on net metering a while ago and I think the upshot was the net metering only happened in real time ie you had to be importing on one phase and exporting on another at the same time for them to cancel each other out. If you imported one minute and exported the the same the next minute then you wouldn't get net metering??

That's great and thanks for the detail......all seems logical so works for me