Is it Better to Have More Batteries or More Solar Panels?

With demand for renewable energy tech continuing to increase, solar panels and battery storage form two key parts of the picture. Together they can maximise your own energy generation and use, whilst minimising your reliance on the national grid. 

But striking the right balance between these two components for a more energy-efficient home can be tricky. 

Weighing up the decision to add more solar panels or more batteries depends on a number of factors, including costs, energy use patterns and long-term savings. This article will take you through the pros and cons of adding more batteries or more solar panels to help you with any future decisions.

Understanding the basics of batteries and solar panels

To understand whether it’s better to add more solar panels or batteries to your home energy system, it’s a good idea to know exactly how these devices work individually and together. 

Solar panels convert sunlight into electricity, which can be used to power your home directly. Most electricity is generated during daylight hours, with peak production occurring when the sun is at its highest point. 

Home battery systems don’t generate electricity, instead they store excess energy (usually generated by solar panels) to use at a later time. 

Of course, you can have solar panels with or without batteries, but the two systems are highly complementary of each other. This comes down to typically energy use patterns. Thanks to the standard working day, the average home tends to use a significant amount of energy first thing in the morning and in the evening. However, it’s at these times when solar panels are less productive, instead producing most of their energy when people are likely to be out of their home. This is where storage batteries come into play, capturing the excess energy to use during peak times.

Having an understanding of your daily energy use patterns is key when answering the question of more solar panels or more batteries. Let’s take a look at the pros and cons of each.

Pros and cons of adding more solar panels

Pros:

• Increased energy generation – You’ll generate more electricity during peak sunlight hours, increasing your own energy production which is available for immediate use.
• Long-term energy savings – More panels lead to less reliance on the grid, resulting in greater long-term energy savings. It’s thought you can save around 70% of your annual bills with solar panels with the estimated average yearly savings ranging from £515 to £1,175.
• Potential for grid export – Excess energy generated can be exported to the grid, earning you money through the Smart Export Guarantee (SEG).
• Long lifespan – Solar panels have a lifespan of 25-30 years, providing a good period of profit after the initial payback period.

Cons

• Upfront investment – An average 3.5kWp (kilowatt peak) solar panel system costs around £7,000 to install, which for most will be a significant initial expense. This sized system will generate around 3,000kWh per year. Larger homes and those that use higher amounts of energy, would need more panels.
• Compatibility issues – Adding more panels to an existing system may not be straightforward, especially if the system is older or incompatible with newer systems.
• Potential upgrades required – Upgrading the inverter and other electrical equipment may be necessary to accommodate additional panels.
• Limited roof space – The number of panels that can be added may be restricted by the available roof space.

Pros and cons of adding more batteries

Pros:

• Increased energy storage – More batteries means you can store more energy. This means you can run your home for longer periods of time just from the battery. If paired with solar panels, this is the cheapest electricity you can get.
• Potential cost savings – By reducing your reliance on the grid, harnessing more of your solar energy or making use of storing cheaper energy, you can significantly reduce your energy costs. You’ll be less exposed to price increases and power disruptions. Smart home integration helps you to optimise your energy use.
• Retrofit compatibility – Batteries can be retrofitted into existing solar panel systems without the need to replace or modify the panels.
• Low maintenance – Modern lithium-ion batteries require little to no maintenance throughout their lifespan of 10-15 years.

Find more benefits on storage batteries here.

Cons:

• Upfront cost – Homeowners generally pay between £4,500 and £10,000 for a well-sized home battery storage system, depending on total capacity, model and installation. For many, this is a significant initial investment, although on the positive side these prices are coming down.
• Limited storage capacity – Depending on the battery size, it may not fully cover a household’s energy needs during extended periods of low solar energy production. This means you’ll still be reliant on grid energy.
• Shorter lifespan – Batteries have a shorter lifespan (10-15 years) compared to solar panels (25-30 years), potentially requiring replacement before the solar panels.
• Reliant on an energy source – Batteries on their own aren’t useful as the energy that goes into them needs to be sourced from somewhere. This is unlike solar panels, which can operate on their own to produce usable energy.

Solar panels vs batteries: Factors to consider

We’ve taken a look at the pros and cons, so let’s take a closer look at the main factors you need to consider between adding more solar panels or more batteries.

Initial costs 

There isn’t too much difference between installing solar panels and batteries. An average 3.5kWp solar panel system costs around £7,000, whilst a well-sized home battery storage system can cost between £4,500 and £10,000. For example, the unit cost for a Tesla Powerwall, with a large capacity of 14kWh, comes in at £5,400. Installation costs on top of this will take it up to the £7,000 mark.

Cost savings 

Both items can help you save money but in different ways.

Solar panels generate electricity, which can be used directly by your home or sold back to the grid, resulting in cost savings on energy bills. On the other hand, batteries store energy that can be used during peak hours when electricity prices are higher. 

With both systems, it’s likely that you’ll still have to buy electricity from the grid to cover all of your energy use.

Energy generation 

Solar panels generate clean, renewable energy, whilst batteries only store energy generated by solar panels or from the grid.

If you have a large battery but are not filling it up regularly with solar energy, adding more PV panels is more advisable to maximise the battery’s potential. This means you’ll be making the most of your battery’s storage capacity and not relying too heavily on the grid to charge it.

If you’re already generating large amounts of energy from your solar array with the majority being sent to the grid, more batteries will help your own energy efficiency and reduce your personal energy waste.

Lifespan 

Solar panels have a longer lifespan (25-30 years) compared to batteries (10-15 years). This means that your solar system will continue to generate electricity long after the battery warranty has expired. When considering the long-term investment, factoring in the potential need to replace batteries earlier than solar panels should be considered.

Available space

The number of solar panels or batteries you can install may be limited by the available space on your roof or in your home. Solar panels require sufficient roof space with minimal shading to maximise their efficiency, whilst batteries need a dedicated area with proper ventilation and cool conditions.

Read up on how big storage batteries are here.

More batteries or more solar panels?

When it comes to deciding between adding more batteries or more solar panels to your home energy system, there’s no one-size-fits-all answer. 

The best choice depends on your individual factors and circumstances, such as your current energy setup and energy patterns.

If you have a large number of solar panels and consistently generate excess energy, adding more batteries makes sense to store that excess energy for later use. However, if you have a big battery that is not being fully charged regularly by your solar panels, adding more panels is the better option.

All things being equal, installing more solar panels generally provides more benefits in terms of energy generation, long-term cost savings and overall efficiency. Solar panels have a longer lifespan than batteries and directly contribute to generating clean, renewable energy for your home.

However, a lot of this clean energy can go to waste if your home isn’t making the most of it during the day when demand is low. 

It’s important to keep in mind that batteries and solar panels serve different purposes and should be viewed as complementary components rather than direct competitors. Both are needed if you want a super efficient energy system.