Adding Battery Storage to an Existing Solar System
Retaining an existing solar investment while adding a Tesla Powerwall 3
The homeowner already had solar panels installed at her property and was benefiting from a Feed in Tariff arrangement.
When she decided she wanted to add battery storage, it was important that the new system could be introduced without disrupting the benefits of her existing solar investment.
The solution was to install a Tesla Powerwall 3 and Gateway alongside the existing solar system, rather than replacing the existing arrangement.
This approach allowed the homeowner to retain her feed-in tariff while adding modern battery storage to her property, including the added benefit of backup power in the event of a power cut.
Integrating new technology with an existing system
Adding a battery to an existing solar installation can be perfectly achievable, but the design needs to take the existing system and its tariff arrangements into account.
In this case, the property’s existing 3 kW solar inverter was already operating under the Feed in Tariff. The existing Aurora inverter had also developed a fault, so it was replaced with a new like for like Solis inverter as part of the project.
The new Tesla Powerwall 3 was then designed to operate alongside the existing solar installation. The DNO approval placed a total site installation limit of 11 kW and an export limit of 6 kW on the property.
To meet these requirements, the Powerwall 3 was configured with an 8 kW output and a 3 kW export limit, alongside the existing 3 kW solar inverter.
This meant the customer could benefit from new battery technology while complying with DNO requirements and maintaining the existing solar system and its Feed in Tariff arrangement.
The completed installation
The project included:
- Tesla Powerwall 3
- Tesla Gateway
- Solis 3 kW inverter
- Existing solar PV system retained
The Powerwall 3 provides battery storage for the property, giving the homeowner greater flexibility over how and when electricity is used.
The Tesla Gateway also provides backup functionality during a power cut. If the mains supply is interrupted, the Gateway allows the Powerwall 3 to supply energy to the home. This helps to keep essential electrical loads powered when the grid is unavailable.
This gives the homeowner not only greater control over the energy generated and stored at the property, but also added peace of mind during an unexpected power outage.
A carefully planned installation
The physical installation also required consideration of the property’s layout.
The Powerwall 3 was positioned to the side of the property, with the location selected to keep the unit as discreet as possible from the main road. Because the wall was slightly curved, Unistrut was required to provide a suitable mounting solution.
The Gateway was positioned separately, with the property’s 100 amp supply and smart meter located on the opposite side of the wall. The installation also included a dedicated earth rod positioned approximately 5 metres from the Gateway.
A positive experience from survey to installation
The homeowner was very happy with the service she received throughout the project, particularly highlighting the time and care taken during the initial survey.
She said:
Barry, the surveyor who visited my property, was excellent. He was knowledgeable, friendly and helpful. He explained everything thoroughly, was happy to answer any questions and there was no hard sell.”
She also praised the installation team:
The installers, Ben and Tim, were competent, polite and professional. They did a great job, worked non-stop during one of the hottest days of the year, and there was no mess left for me to clean up.”
Throughout the project, Samantha was the customer’s main point of contact:
“She has been pleasant and helpful, communication has been great and all queries and questions have been responded to promptly.”
The homeowner concluded:
“I’d highly recommend The Little Green Energy Company 👍”
Adding battery storage without losing the value of existing solar
For homeowners with an older solar installation, adding a battery does not necessarily mean replacing the existing system or giving up an established Feed in Tariff arrangement.
With the right design, the new battery system can be planned around the existing installation, allowing customers to preserve the value of their original solar investment while benefiting from newer battery technology.
The addition of the Tesla Gateway also means the system can provide backup power during a power cut, allowing the Powerwall 3 to continue supplying energy to the home when the grid supply is interrupted.
This project demonstrates how careful system design can bring together an established solar installation and a modern Tesla battery system to meet the needs of the homeowner today, while preserving the benefits of their original solar investment.
