BATTERY STORAGE

Electricity batteries help you make the most of renewable electricity from a solar PV system or wind turbine. If you already generate your own renewable energy, a battery storage system can reduce your fuel bills and carbon emissions.

For example, your solar PV system will generate electricity during the day when you’re out at work, and this can be stored in your electricity battery for you to use in the evening.

Batteries, depending on the model you choose, can be modular, allowing additional storage capacity to be added to at any stage to tie in with your changes in lifestyle. ALL batteries can be retro fitted to an existing generation system (solar PV etc.)

We caveat the following by saying that “every day is a school day” when it comes to battery storage as this is an ever evolving technology. We have been installing battery storage systems for 6 years now, and have experienced a steep rise in demand since 2019, but due to its continuous evolution, no one can really declare they are totally up to date with the changes nor be an out and out expert in the field. We therefore do not claim to be out and out experts, but we do have the advantage over many as we have the experience of having installed many systems and  our knowledge is based on our experiences to date.

The following script is based on that experience:

There are two types of battery storage systems: “AC Coupled” and “DC Coupled”.

DC Coupled Battery Storage

The above illustration shows you how the electricity from the solar panels is sent to the hybrid inverter which, in turn, decides to send the electricity to a battery or straight into your house.

DC coupled batteries are run from a hybrid inverter.

A hybrid solar inverter is the combination of a solar inverter and a battery inverter into a single piece of equipment that can intelligently manage power from your solar panels, solar batteries, and the utility grid at the same time. A CT clamp is run from the hybrid inverter and connected to your incoming supply. This allows the hybrid inverter to know whether or not you are importing electricity or exporting (exporting would happen during times when you are not using all the electricity being generated from your solar panels. This information allows the hybrid to know when to send any excess (unused) solar electricity into a battery instead of sending it into your house and then discharge the battery stored power into your house when needed (typically at night time.)

Hybrid inverters can also charge the batteries by drawing electricity from your mains supply. This allows you to top up the batteries (typically from November to February) should they not be lying fully charged for a long period of time. This function also allows you to fill the batteries on cheaper off peak electricity (to discharge during peak rate times) should you have that type of tariff.

Please note that,most hybrid inverters have the ability to discharge electricity from the batteries during a power cut HOWEVER any of your electrical circuits that are receiving (typically these inverts do up to 3 circuits in a retro fit scenario) MUST BE EARTH SEPARATE FROM THE DNO SUPPLIED EARTH – this is a legal requirement to allow the DNO to work on their cables during a power cut in the safe knowledge that nothing is being sent down their cables.

All lithium ion batteries struggle to charge at @ zero degrees centigrade, and may opt for safe mode at temperatures below this, so it is worth considering having them in a relatively warm area in the winter or lagging them to prevent failure, as sometimes (as we have experienced in the past) if they go to safe mode when they have a low charge, an engineer is required to go to step to recharge them as they cannot be forced charge by the inverter.

There are many manufacturers of Hybrid inverters, AC Coupled inverter/battery chargers and batteries, but all are  predominantly manufactured in China (with a few exceptions) and all of them come with an app that allows you to see what is being generated and stored.You may find it a confusing when researching battery storage as it can be difficult to determine what is fact and what is fiction.   We have used various makes of both throughout the years and are happy to advise on which ones we feel are the best based on availability, performance to date, and most important – manufacturers backup. Please note that “household names” are not necessarily the best  batteries.

AC Coupled Battery storage

An AC coupled battery storage system is a battery storage system where the battery is charged and discharged from an AC coupled inverter/charger which stands alone and is not connected to solar panels. The inverter/battery charger is wired into your mains supply and charges the batteries in a similar way to a standard battery charger. As with a hybrid inverter, a CT clamp is fitted to the incoming supply to allow the inverter to know whether or not electricity is being sent to the grid, and when there is electricity being sent to the grid it can switch on to catch the electricity and send it to batteries to be discharged later. So, this type of battery storage does not necessarily need to be coupled with a solar PV system and can be used purely to draw on off peak electricity to discharge during peak rates times.

Please note however, if you connect an AC coupled inverter into your house the D.N.O. (Distribution Network Operator) class this as a generator. Therefore, should you already have a solar PV system on your house then you will need to make a G99 application before you can install an AC inverter/battery charger – this is a legal requirement.

General

All lithium ion batteries struggle to charge at @ zero degrees centigrade, and may opt for safe mode at temperatures below this, so it is worth considering having them in a relatively warm area in the winter or lagging them to prevent failure, as sometimes (as we have experienced in the past) if they go to safe mode when they have a low charge, an engineer is required to go to step to recharge them as they cannot be forced charge by the inverter.

There are many manufacturers of Hybrid inverters, AC Coupled inverter/battery chargers and batteries, but all are  predominantly manufactured in China (with a few exceptions) and all of them come with an app that allows you to see what is being generated and stored.You may find it a confusing when researching battery storage as it can be difficult to determine what is fact and what is fiction.   We have used various makes of both throughout the years and are happy to advise on which ones we feel are the best based on availability, performance to date, and most important – manufacturers backup. Please note that “household names” are not necessarily the best  batteries.