Batteries
Your guide to Solar Battery Storage
Solar Battery Storage
Electricity is stored as DC (Direct Current) and there are two basic methods of converting solar electricity for storage.
The first method is to simply feed DC electricity directly from the solar array into the battery and then use the existing DC – AC solar inverter to convert the solar power for household use as required. This type of inverter is called a Hybrid, the advantage being that it is cheaper to use than a single inverter. The downside is that if you already have a solar system installed the current inverter will require changing. However, if you are having a new solar system fitted or changing an old inverter this makes perfect financial sense.
The second method is an AC side connection which in effect is a complete battery storage system totally separate from the solar array and more expensive because a second inverter is required. If you have a Solar Edge optimized system fitted, then this will require an AC side connection as the Solar Edge inverters cannot be exchanged. Also, if you are contemplating storing electricity from the grid at cheap overnight rates this will also require an AC side connection.
An AC side connected battery will discharge at a higher rate than a DC side battery, plus it can be charged from the mains using an overnight cheap rate if required.
The next thing to consider is storage capacity and whilst batteries come in many sizes the average household will require a 6 – 10 kWh (Kilowatt Hour) storage battery. As an example, the average hot water kettle uses 2kW per hour, so a 6kWh battery would continuously boil a kettle for 3 hours.
We supply and install three types of battery:
Solax AC side connected (can be retrofitted):
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5.8kWh Discharge rate 3.68kWp £4,652.11
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5.8kWh Second unit retro fitted £3,213.16
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11.6kWh Discharge rate 5.00kWp £7,510.97 (two x 5.8kWh)
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17.6kWh Discharge rate 5.00kWp £9,836.05 (three x 5.8kWh)
The Solax Hybrid DC side connected Tri Power can only be fitted to new installations. 5.8kWh, with a discharge rate of 5kWp, priced at £5,138.60 fully fitted.
DC side connected (can only be fitted to new installations), with a discharge rate of 5kWp, priced at £4,976.42.
A manual changeover switch, will provide electricity during a power cut to the above batteries and is priced at £485.
The first battery would cost £8,783.78 including gateway and installation.
The Powerwall has the advantage of high-capacity storage (13.4kWh) plus
off grid capability.
Additional Powerwalls are priced at £7,656.65, up to a maximum of six on
a single-phase supply.
Its Discharge rate 5.00 kW. (Peak 7.00kW) Emergency back-up and off-peak charging capability included.
There are several other battery packs on the market, and we will be pleased to quote for these however some are composed of batteries and controllers from different suppliers, and this can cause issues with warranty of work. We feel it better to source a complete package from one manufacturer.
Whilst the main usage of a battery would be at night-time when the solar system is not functioning, they can also work during the day to smooth out peak usage or when the sun goes behind a cloud. Once the roll out of smart meters is almost complete the electricity suppliers intend to introduce varied pricing bands throughout the day and again the battery systems will help to smooth the costly peak bands.
Testimonial
"Dear David
Just a little bit of feedback from the 2 extra Powerwalls that have finally been added to my system.
As I expected (and was the case with the original install), your team were nothing but courteous, professional and meticulous. I mean, they even vacuumed the area of the garage where they’d been working!
The Powerwall system is working perfectly. The first “Off Grid” test resulted in circuit breakers tripping and a few shenanigans, but all breakers were swiftly replaced, and everything seems to be working perfectly.
Top quality service! "