Solar, Batteries and Retrofit: Why the Warm Homes Plan Changes the Conversation

For a long time, retrofit has mainly been discussed in terms of insulation, heating upgrades and EPC ratings. These remain essential, but the conversation is changing.

The UK Government’s Warm Homes Plan places much greater emphasis on combining energy efficiency measures with technologies such as solar panels, batteries, heat pumps and insulation. The plan includes £15 billion of public investment and aims to upgrade up to 5 million homes by 2030.

For landlords, councils and housing providers, this matters because retrofit is no longer only about reducing heat loss. It is increasingly about how homes generate, store and use energy.

That shift creates new opportunities, but it also means retrofit strategies need to be more carefully designed.

Solar PV on our project in Port Talbot, Wales

Solar should not be treated as a bolt-on

Solar PV can be an excellent addition to retrofit projects. It can reduce reliance on grid electricity, lower running costs and support the wider move towards low-carbon homes.

Demand is already rising. MCS reported that UK rooftop solar installations reached a record level in 2025, surpassing the previous annual record set in 2011.

However, solar works best when it is part of a whole-house strategy, not simply added at the end of a project.

For housing providers, this means looking at:

• roof condition and available space

• orientation and shading

• existing and future electricity demand

• whether heat pumps are planned

• whether battery storage is suitable

• how residents will benefit from the generated electricity

A roof that is due for replacement, for example, should not be fitted with solar panels without considering the wider maintenance and retrofit strategy. Equally, solar PV should be coordinated with structural capacity, fire safety, access, metering and long-term maintenance.

Where batteries change the equation

Battery storage is becoming an increasingly important part of the retrofit conversation.

Without a battery, solar electricity is used when it is generated. Any excess may be exported to the grid. With a battery, more of that generated electricity can be stored and used later, such as during the evening when demand is often higher.

This can be particularly relevant where homes are being upgraded with:

• heat pumps

• electric hot water systems

• mechanical ventilation

• electric vehicle charging

• time-of-use tariffs

The Warm Homes Plan specifically recognises the role of batteries, with the government stating that low-cost finance could support the upfront cost of solar and battery installations.

Energy Saving Trust has also suggested that funding packages for solar panels and batteries could be worth around £9,000 to £12,000 per home, based on current costs.

For landlords and housing providers, this makes battery storage a serious strategic consideration, particularly where long-term energy affordability and resident benefit are priorities.

Why this matters for councils and housing providers

For local authorities and housing associations, the Warm Homes Plan creates a bigger strategic opportunity than previous measure-led funding routes.

Instead of thinking in isolated upgrades, housing providers can start planning retrofit programmes that combine:

• fabric improvements

• low-carbon heating

• renewable generation

• storage

• resident energy savings

This is especially important for low-income households and those in fuel poverty. The Warm Homes: Local Grant, delivered by local authorities in England, is designed to improve energy efficiency and increase low-carbon heating installations in low-income homes. Energy Saving Trust notes that the scheme will allocate £500 million to 73 projects across 270 local authorities over three years.

For councils, this means the challenge is not only securing funding. It is creating retrofit programmes that are technically coordinated, compliant and deliver meaningful outcomes for residents.

The risk of poor coordination

As funding expands, there is always a risk that projects move too quickly.

Solar, batteries, heat pumps and insulation all interact with the building and with each other. If they are designed separately, problems can arise.

Common risks include:

• solar installed before roof upgrades

• batteries specified without understanding actual demand

• heat pumps installed before fabric improvements

• ventilation overlooked during airtightness upgrades

• resident benefit not clearly planned or explained

• maintenance and access issues not considered early enough

A successful retrofit project should not be a collection of disconnected technologies. It should be a coordinated design strategy.

This is where PAS 2035 and whole-house retrofit thinking become vital. Assessment, design, installation and evaluation all need to work together.

A more intelligent retrofit model

The Warm Homes Plan signals a move towards a more intelligent model of retrofit.

Homes are no longer being viewed only as buildings that need insulation. They are becoming part of a wider energy system.

That means future-ready retrofit needs to consider:

• how much energy the home needs

• when that energy is used

• how much can be generated on site

• whether energy can be stored

• how residents use the home

• how systems will be maintained over time

This is a more complex conversation, but it is also a more exciting one. Done well, solar and batteries can strengthen retrofit outcomes and help residents benefit from lower energy costs for years to come.

How Target Green can help

Target Green supports landlords, councils, housing associations and contractors with design-led retrofit strategies that consider the building as a whole.

Our team can help assess whether solar PV, battery storage, heat pumps and fabric upgrades are suitable for your housing stock, and how these measures should be sequenced to deliver the best outcome.

We support projects through retrofit assessment, PAS 2035 design, coordination and technical advice, helping clients avoid disconnected measures and build programmes that are practical, compliant and future-ready.

If you are exploring solar, batteries or wider retrofit upgrades as part of a housing programme, Target Green can help you develop a joined-up strategy that works for the building, the resident and the long-term performance of your stock.