A couple of weeks ago I wrote the first post about my journey to install solar panels and battery storage at my home in Bath. Read that post by clicking here. This is part 2, the plot thickens!
I've now had a quote, done my research, bombarded Powervault and Orca Renewables (the Bristol based company who quoted to install but work nationwide) with questions and come to some decisions!
Here are the raw numbers...
- System size 4.2kW
- Total system price £10,626 (no VAT, see below for more information)
- 10 solar panels made by JA Solar
- 1 Powervault P5 battery, capacity 10kWh
Some very clever software used by ORCA has estimated my annual savings at £1,212 but I think we need to be cautious here, there are a lot of assumptions to get to that figure!
I have a 2 oven Modern style Aga cooker by Blake & Bull of course! It runs on eControl Series X and I also have, and LOVE, the optional Instaheat hob. Read my Instaheat review here. We sell and install electric Aga cookers (remanufactured by Blake & Bull) but convert far more Aga cookers to electricity. It's the most cost effective route to a modern, controllable cooker. Find out more here or click below to enquire!
I also have a small air conditioning unit in the conservatory which runs along the back of the house. It's a cheap 1980's conservatory so is the right temperature for only about 15 minutes twice a day! It's freezing before 8am, boiling from 8.15am and only briefly liveable again for another 15 minutes in the early evening. In the summer the A/C keeps it usable as a playroom and stops my daughters getting cooked, in the winter it will provide efficient warmth quickly when we want to use the room. Not everyone realises that A/C units are also air-air heat pumps so very efficient at creating heat in the winter! 1kW electric in should equal approx 3kW of out.
The A/C and Aga mean I use more electric than the average home AND more in the summer when (in theory!) the sun is shining. This means I think the estimated savings above too low. I think we'll save £1500 a year easily.
That puts my payback at about 7 years and the feels about right. I may be able to do even better I hope! I think with a slightly bigger system, 6kW maybe, I'd be running my house largely for free. No gas bill for the Aga, a small gas bill for the central heating and a small electric bill from the times the battery is exhausted and the sun isn't shining. I'm excited to find out!
I had assumed we'd use both the roof of the house and that of a detached garage in the garden but interestingly ORCA advised that installing on the garage was pointless and managed to get a single extra panel on the roof of the main house instead. The garage is more shaded and nearby trees mean the panels will get dirty quickly and lose efficiency. One extra panel up high on the main roof will equal a whole roof of panels lower down.
The panels themselves are by JA solar. They are common and I have no reason to assume there is anything better out there!
The battery I think is the really interesting thing and I've asked a lot of detailed questions!
It will be a Powervault P5 which is brand new and available in about a month (from July/August 2024). It's a stackable, modular system so it can be added to at a later date if need be. Both the initial installation and subsequent additional battery module purchases are free of VAT. This is new from February 2024. The P5 will also have an automatic switchover 'gateway' that means in the event of a power cut my home will carry on serenely with power to Aga, lights, A/C unit and everything else! Even the central heating would carry on as the combi boiler would still have power! This is a key consideration for me, no point having a battery if you can't access it when you need it most! I know power cuts are rare, and getting rarer, but this is just one of those simple things that could make life much easier in winter with two small girls in my house!
I've done detailed research into batteries and can find nothing better. Not even the Tesla powerwall. There are cheaper batteries, slightly, but these don't have the clever 'SMARTSTOR' tech. This is an AI powered (isn't everything these days!) algorithm that will charge the battery when sensible and discharge it when sensible. What does that mean?
If the battery has some charge and sun is forecast then SMARTSTOR will use that power to run the house knowing that it will be able to recharge soon. If the sun is not shining but its windy then SMARTSTOR may choose to charge the battery on cheap rates from the grid (electricity is cheap when its windy, all those wind turbines start spinning super fast!). If the battery has been charged on cheap rates and then its a dark, still December evening then all your power will be from the battery to avoid buying expensive electric just as everyone else is doing the same! It's this technology that means your average cost per kWh purchased from the grid will be much lower than more manual or 'dumb' systems.
You win twice with solar + battery storage. Once when you generate your own power to use, and again when you DON'T have to buy expensive daytime power like everyone else!
My quote from ORCA estimates that I'll use 95% of power I generate (selling it back to the grid is so little money as to be pointless) which will comprise 41% of my overall electricity usage at home. I suspect it will be lower than this so a ket source of savings will be those clever purchasing decisions by the SMARTSTOR AI brain.
To make all this work of course you need the right tariff. Octopus Agile works well with the Powervault battery and will talk to the battery and keep it up to date on current costs per kWh so it can decide what to do.
I don't want top be thinking about all this constantly (I have enough to do already) so after a couple of months I'm told I'll just get used to it all and start ignoring it all as it does its work in the background. Sounds perfect to me!
If you can get your head round these graphs they are a fascinating insight into how it all works over the year. This is the future. Clever tech working quietly in the background to make our lives warmer and brighter at no cost to the earth. My small contribution to the (much longer than people think!) journey to net zero!
