Confused about what spec system to get. Can anyone help?

[HomerJay]

Firstly, can I apologise for any incorrect terminology- I frequently get my kw mixed up with kWh etc!
- Our annual consumption is around 6000kw /16kw a day
- We have enough space on our roof for 18 panels (2 rows of 9)
- We’ve been advised to get anything from a 5kwh to a 19kwh battery system.
- We’ve been advised to get an inverter that’s 5kw or 7kw
- We have a plug in hybrid with a 8kw battery (Ionic)
- We will shortly be on the Octopus Go tariff

Our idea is that during the spring and summer months we will generate enough from the panels to satisfy demand and also store some in the battery for the evenings and next morning.
In the winter / autumn, we hope that the panels will still provide some useful energy but we’d like to make up the shortfall with power from the grid bought at the off peak (7.5p) tariff and stored in the battery, thus minimising any peak rate grid purchases.

We’d also like to heat the hot water tank with any spare power if possible.

Whilst most of this makes sense, we’re confused about what battery & inverter size we should go for that would do what we’d like it to do.

Could any of you chaps help? This is all very new and confusing to us - we’ve never had to worry about the cost of power until now!

 

[johnb2713]

I'm pretty much in the same boat or very similar boat as you.

Back in April this year we had 16 Hyundai panels installed, a 6kW Hybrid Inverter and a 7 kWh battery along with ZAPPI and EDDI.

EDDI is the energy diverter, any excess solar after charging batteries and supplying the house is dumped into the immersion heater, if theres 800w excess for example, it puts 800w into the immersion even though the element is 3kW.

We have found that our system is nigh on perfect size wise for summer use except if were doing a Sunday roast and the washing at the same time. To that end I'm adding an additional 14kWh battery and another 5kW Inverter.

Throughout the summer I've my car BMW i£ and the wife's Hybrid (Outlander PHEV) from our solar, we are on GO and do fill charge the battery every night.

It was all prompted when GO tariff was renewed and our payments went up from £178 to £565 per month. All monthly bills are between £60 and £70 and we havent used any gas at all, previously we used gas all summer for hot water.

We use 12000 kWh of electricity per year, we do run 2 cars and heat pumps so it's not too bad. Battery size go for as big as you can afford and the inverter likewise, you need to consider your usage, 2 kW oven, 3 kW kettle and a tumble dryer running at 3 kW will have soon given you an 8 kW load, if you have a 6 kW inverter, 6 will come from the solar & battery, and shortfall from the grid. You need to think about worst case scenarios - breakfast Toaster on and kettle boiling will be around 5 kW and so on.