Battery Storage – Your Handy Guide

Maximising energy use from a solar photovoltaic (PV) system is the aim of the game. By using all the energy generated by a solar PV system the owner gets the best pay back on the initial investment. The technology everyone is talking about to help to achieve this is battery storage.

Why store your generation?

Although not unheard of for a domestic installation to use their entire generation total, it’s common for a portion of this to be exported back to the national grid. The deemed export tariff exists to address this likelihood, paying generators an export tariff for half their generation.

Although you get paid (4.9p/kW) for this ‘lost’ generation, it is roughly 30% of the price you pay when importing an average kilowatt hour (kWh) from the big six (currently around 15p/kW). By storing the energy you’d otherwise export in a solar PV battery storage system, you can power your home after daylight hours and reduce the amount of energy you import (and pay for) – and your FIT will not be affected.

How should I store?

The answer is simple – a solar PV  battery storage system. But how do you find out which is the right one for you? Good question – and if you have done any research on batteries so far you will know it is a bit of a minefield. Lots of manufacturers want to get in on the act and offer a solution. The industry is touting solar PV battery storage as the next hot product and nobody wants to miss out. Fear not! Our handy guide gives an overview of battery storage systems and we review our top three enquired after systems.

New Installation or Retrofit to Existing Installation

This guide looks at batteries designed for new installations as opposed to retrofitting to existing solar installations which we will explore in a later article.

Tesla Powerwall

Progression has been steady for Tesla on their Powerwall model, and this year will see the arrival of their upgrade – the Powerwall 2. At first glance, it’s easy to be impressed by the flawless design and large capacityof the unit. However it is not a small piece of kit measuring 1.15m tall and a weighing a whopping 120kg. With the option to wall or floor mount, inside or out, there’s no limitations for the domestic market (except possibly the strength of our installers!).

The battery itself comes with a useable capacity of 13.5kWh, which can be used with a standard 4kW domestic system and store power for a three-bedroom house – which typically uses 15kWh a day. The unit itself houses an inverter, avoiding the need to swap out any incompatible models, or purchase any additional components.

On the downside – the price. Tesla have certainly built their name and reputation, and branding of such a product can ramp up the price. The current May 2017 release price of the Tesla is estimated between £5,000-£7,000 – the current market price for a full 4kW system. Although design advances are par for the course at Tesla, it doesn’t bode well for the end user – production of the ‘Gigafactory’ isn’t due to be completed until 2018, meaning prices of the current unit aren’t likely to drop anytime soon.

This could make the Tesla less accessible for some households – but there are alternatives.

Goodwe

Hybrid inverters enable domestic solar PV systems to convert generated electricity into storable power. The inverter can intelligently control the flow of energy and act upon demand, storing any excess in a separate battery pack.

The ES series – one of three models currently offered by Goodwe – isn’t as easy on the eye as the Powerwall but is less imposing, scoring points for accessibility of design. It is important to note that space must be provided for the battery pack and unfortunately, current packages don’t offer the same size storage as the Powerwall – a mere 6.5kWh. Usage and export amounts do differ from household to household, so it’s difficult to say whether you’d really see a negative impact in the decrease in size without looking at each individual case.

With lesser storage capabilities, there is a slight drop in price – a bonus for many users. The addition of a hybrid inverter and battery storage system to your domestic installation could look to cost you between £4,000-£5,000, and even this has some room for movement by allowing the option to reduce the battery size even further.

It’s noteworthy to mention that you don’t have to install batteries with your hybrid inverter straight away – a brilliant perk for a first-time installer looking to spread out their capital expenditure. By installing a hybrid inverter, you’re paving the way to an easier upgrade to battery storage in the future.

These kinds of model can certainly rival Tesla’s inflexible storage/inverter options – but can there be any flexibility on price (often the overall deciding factor of new technologies)?

Solax

The pick of our budget bunch is the X-Hybrid, Solax’s third generation inverter with a range of new features and battery options. Packages are currently being sold at around £3,500-£4,000 for domestic systems, significantly reducing the overall pay back of a fully installed system. The price does reflect a further reduction on the storage capabilities – currently 4.8kWh – but as a furtive introduction into reducing your export, it builds great foundations for later upgrades.

The design of the unit surpasses that of the Goodwe model – the sleek appearance and option to floor or wall mount the battery pack even rivals the Tesla Powerwall, which would dwarf the X-Hybrid’s 47cm height!

For those dedicated to keeping track of their generation and export, Solax have a handy online portal, accessible through desktop or mobile applications – a great addition to help users understand how they can get the most out of their self-consumption.

No matter what system you install, it certainly makes sense to prepare for grid independence in the future. The Greener Group are accredited installers of Tesla Powerwall products and a variety of other products – if you need guidance on what system would work with your consumption, contact us today.

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