Which storage battery

Screwdriva

QrizB said:

The price is in the right ballpark.

Is that an AC-coupled battery, which will leave your existing solar PV alone and shouldn't affect your FIT payments (assuming you get them), or are they proposing a hybrid inverter and a DC-coupled battery?

These are very pertinent questions. Most SolarEdge inverters are hybrid these days, so I'm assuming they are offering the 10kW DC coupled battery. The price you have shared is somewhat accurate (£~5K). If it needs a replacement 2.2kWh hybrid inverter, expect to add another £1K on top. 

ludditeJazz said:

My winter battery demand is rarely over 12kWh (after accounting for solar generation),

This is key! Assuming you average 9kWh per year, you do not consume enough to offset the upfront cost of a battery.  You are better off selling your excess solar for the most £ you can get for it. 

ludditeJazz

Thank you, sorry to delay. Duracell Energy Dura5 Battery, just asking them if they proposing a hybrid inverter and a DC-coupled battery. presumably I'll be able to switch the solar PVs to feed the battery or FIT grid depending if future prices change? 

ludditeJazz

Great, thanks. My plan is to buy cheap elec at night to store and use during the day. This doesn't affect my payments for generating solar (installed in 2016); only my choice whether to feed it in under FiT (7p I think) or into battery. I believe I'm paid for generating it regardless. 

Screwdriva

ludditeJazz said:

Thank you, sorry to delay. Duracell Energy Dura5 Battery, just asking them if they proposing a hybrid inverter and a DC-coupled battery. presumably I'll be able to switch the solar PVs to feed the battery or FIT grid depending if future prices change? 

The Dura5 is a 5kW battery. Are they installing 2 of these? 
 
Apologies for being controversial but I do not believe 10kW of Duracell at £5.2K represents good value. You can have a larger, far more capable 13.5kW DC coupled Tesla PW3 for £7.2K installed (£2K more than Duracell but comparable price per kW of storage). 

My point here is to highlight the poor value proposition of the Duracell battery (vs. recommend you get a PW3).

QrizB

ludditeJazz said:

Thank you, sorry to delay. Duracell Energy Dura5 Battery, just asking them if they proposing a hybrid inverter and a DC-coupled battery. presumably I'll be able to switch the solar PVs to feed the battery or FIT grid depending if future prices change? 

If they're proposing a hybrid inverter it'll complicate your FIT payments. AC coupled would be simplest., if fractionally less efficient.

ludditeJazz

thanks both, very useful indeed. 

@QrizB I'm only paid 7.1p to export under FiT (the 17.5p generation payment I get either way) and I'll be paying Octopus 7p for off peak power that fills the battery so I guess the type of inverter is not crucial, although the spread between the two prices could change I guess. I'll check to see if I can get AC now though. thanks

@Screwdriva noted re the value, since it's only a handful of days/ year that my consumption exceeds 10kw I'm tempted to go with the smaller/ cheaper Duracell I think...

@both one thing I don't know is how easy it is to programme all this. initially the rules will be simple - send all solar elec into the grid under FiT, and buy elec until battery full between midnight and 5am. but might one day be more nuanced! I spent hours working out the benefits from storing my solar in the battery, how much and at different times of year, but when I found out that the EV tariffs were available, it was all irrelevant 🙈😆

Qyburn

ludditeJazz said:

 (I’m currently favouring Octopus Intelligent Go - they tell me I can use home battery in place of EV).

How does that work? On the web site it says you need to link up a compatible car or charger. And directs you to Intelligent Octopus Flux for home solar/battery systems.

It's worth doing the maths for these options. For example I'm currently on Go for import @8.5p and Outgoing Fixed at 15p for export. IOF would be 14.25p more expensive for import, but pays 7.75p more on export. This breaks even if export is around 1.8 times import.

thevilla

If I didn't already have two, I'd wonder if Go is such a good deal that it'd be worth investing in a cheap EV runaround.  Contrary to most of the UK press they are available second hand.

QrizB

thevilla said:

If I didn't already have two, I'd wonder if Go is such a good deal that it'd be worth investing in a cheap EV runaround.  Contrary to most of the UK press they are available second hand.

For years, my EV on Go was made by Tamiya ...
Now we've got an EV that humans can fit inside, we've qualified for IOG.

Qyburn

thevilla said:

If I didn't already have two, I'd wonder if Go is such a good deal that it'd be worth investing in a cheap EV runaround.  Contrary to most of the UK press they are available second hand.

I wasn't asked, just selected the tariff online.