Solar Panels vs Insulation: Which Is The Best Investment?

Solar panels and insulation can both save you money on your energy bills. However, both involve high upfront costs to install – which can vary depending on the types of solar panels and insulation you opt for. This post compares the two options to help you decide which is the best investment in the long run.

How much money can you save with solar panels?

Adding solar panels to the roof of your home could boost its green credentials
Credit: Deposit Photos

It’s possible to completely eliminate energy bills by installing enough solar panels to fully power your home. However, you generally need quite a lot of solar panels  – a three bedroom house will typically require a 3.5kW 10 panel system to be fully sustainable.

How much do solar panels cost to install? About £9000 for a 3.5kW solar storage system. Considering the average annual energy bill for a UK three bedroom home is roughly £1000, it could take 9 years to make a return.

Obviously, this is just an average and many other factors can influence how much of a good investment panels are such as where you place the panels, what the local climate is like, how well you maintain the panels, the types of electrical appliances you use in your home and how regularly you use each of these appliances. 

Adding less solar panels could cost less upfront but still reduce your energy bills significantly. Some people find this to be a better investment. 

It’s worth noting that solar panels can boost a home’s value by 4% or more. So even if you sell your home before you’ve made up the costs in energy savings, you’ll likely make a profit when you sell.

How much money can you save with insulation?

Insulation added inside a loft conversion
Credit: Deposit Photos

Insulation can help to trap heat in your home longer so that you don’t need to use as much energy to keep it warm during colder months. There are many different forms of insulation, which can provide different levels of heat loss reduction. Loft insulation can typically reduce heat loss by as much as 25%, as can replacing all your single pane windows with double glazing. 

Costs can vary depending on the type of insulation you install. The average cost to spray foam insulate the loft of a three bedroom property is about £4000. Meanwhile, in your average three bedroom home with eight windows, it costs between £8000 to £12000 to replace all the windows with double glazing.

How much money can you save? Well, when you consider that almost 60% of energy consumed goes into heating our homes, heat loss reduction of 25% means that both loft insulation and double glazing could each save you about £150 per year. 

It could take many decades to actually make a return through energy savings alone. However, considering both loft insulation and double glazing can improve your EPC rating, each one could potentially boost your home’s value by 4%, resulting in big returns if you sell. 


Solar panels are technically the best investment. If you install enough solar panels to go off-grid, you will essentially have no energy costs to worry about once you’ve paid off the cost of installing your solar panels. 

Insulation can still result in significant savings. But it will take longer to pay off the cost of installation unless you’re planning on selling your home soon. 

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