Adding battery storage after solar

In this article we will look at the possibility of adding battery storage on to your existing solar system, the possibilities, constraints, and potential costs involved with doing so. It’s worth pointing out however, if you do have plans to upgrade in the future, please make our team aware when obtaining your quote. This will allow us to design your system with upgrades in mind, which could reduce your equipment, installation, or approval costs when the time comes.

We know that going green and buying solar can be expensive and it may not be within your budget to have a battery system installed at the same time. We would recommend having it installed at the same time rather than later, if you can, due to several factors:

• Labour and consumable costs
• Equipment upgrade costs and compatibility
• DNO approvals

Labour and consumable costs

Labour and consumables could potentially be one of the biggest costs when installing additional equipment. This is because most installs have a standard ‘mobilisation fee’ which includes a certain number of hours labour. This means that the cost of installing a solar system and then mobilising later to install a battery could become very expensive when compared to the individual number of hours that’s needed on site to install a battery, if the teams are already at your property.

Depending on where the equipment is to be installed and the connections that are needed to other pieces of equipment within the installation, you may find that cable routes and potentially entire cable runs need to be removed or altered to ensure everything is installed correctly. Of course if all your equipment is located close together, the extent of this may be minimal.

Equipment upgrade costs and compatibility

Depending on which type and brand of solar system you are having installed, and which battery system you want to add on later, this could become expensive replacing equipment.

If you wish to install a Tesla battery, this is simple and can sit alongside any existing equipment, without the need to replace or upgrade anything. If you have an existing Solax or SolarEdge system and want to use either of those manufacturers batteries, you will need to make sure that it’s compatible, i.e. a SolarEdge battery can’t operate with a Solax inverter. You’ll also need to make sure that if it is technically compatible, that the equipment you have installed is suitable to control a battery.

A standard solar inverter is referred to as an “inverter”, whereas an inverter that controls a battery and a solar system is referred to as a “hybrid inverter”. What’s the difference I hear you ask… A hybrid inverter can convert your solar panels energy as a standard inverter can, however it also has the components to charge and control a battery. Depending on current offers, purchasing a battery at the same time as solar could mean it’s eligible for 0% VAT!

For example, if you had a standard SolarEdge inverter and wanted to add on a SolarEdge battery, you couldn’t do this without changing the inverter to a ‘hybrid’ model. This is why it’s important to consider and discuss future requirements with our team when producing your design. We can design with this requirement in-mind and install a hybrid inverter at the same time as your solar system. This would work perfectly normally for your solar system and would allow a simple ‘plug & play’ setup for your new battery when the time comes, without any costly inverter upgrades.

DNO approvals

Depending on the size of your solar system and the type of battery you want installed, you may not need DNO approval, however if you were to install a battery storage system, this may mean you may need DNO approval, or have to gain approval for a second time.

As the inverter size normally dictates the approval that’s needed, if you installed a Tesla battery afterwards, approval would be needed. If you installed a battery that connects directly to the inverter, you may not need approval, however you may find that the inverter is too small to power your home from the battery and you may need to upgrade, which would require approval.

If you have a battery installed at the same time, all of the approval process is managed at once and permission obtained for the overall system. As this is commonly one of the longest delays in the process (up to 45 working days), not having to request approval again really can save a lot of time.