What are the benefits of combining commercial solar with battery storage?

Key takeaways

• Solar panels without battery storage typically achieve 40% to 55% self-consumption. Now add appropriately sized batteries and self-consumption rises to 75% to 90%.

• Every unit of electricity you consume from your own generation saves you the full grid rate (currently 25 to 28p/kWh). Every unit you export earns 3 to 15p/kWh. The financial gap between those two numbers is why self-consumption drives higher returns.

• Battery storage unlocks benefits beyond self-consumption: peak demand reduction; time-of-use tariff optimisation; grid export limitation compliance; and supply resilience.

• Commercial battery storage costs have fallen 30% to 40% since 2022. A 100kWh system currently costs between £20,000 and £40,000 installed.

• Installing solar and storage together costs less than installing them separately. One scaffolding visit, one G99 application, one commissioning process.

A solar installation without battery storage is a bit like a factory that only operates half a shift. The panels generate electricity during daylight hours. If the building cannot absorb all of it in real time, the surplus flows to the grid at export rates that are a fraction of what grid electricity costs to import. The opportunity to use that self-generation more productively passes.

Add batteries and the picture changes. Generation that would have otherwise been exported (at a lower tariff) gets stored and used later, at times when the building needs it most. The system works harder. The financial return improves. And a set of operational advantages open-up that solar alone cannot deliver.

This article covers what those advantages actually are, how they are valued and which types of business tend to benefit most from the combination.

Benefit 1: Higher self-consumption and stronger financial returns

Self-consumption is the percentage of solar generation used on-site rather than exported. Without battery storage, a typical commercial installation achieves 40 to 55% self-consumption. The rest is exported under the Smart Export Guarantee (SEG) at rates currently ranging from 3p to 15p per kWh on commercial tariffs. With an appropriately sized battery, self-consumption typically rises to 75 to 90%, according to analysis by EvoEnergy based on UK commercial installations.

The financial case for that shift is straightforward. Every unit you consume from your own generation avoids buying grid electricity at the commercial (grid) rate, currently 25 to 28p/kWh for large commercial and industrial consumers in 2026, according to Eden Sustainable's internal pricing data. Every unit exported earns two to three times less per unit than that. Maximising self-consumption is always the better financial outcome.

Battery storage is what makes high self-consumption achievable. A manufacturing facility running two shifts, a cold storage warehouse running 24 hours, a multi-academy trust with evening sporting events: all of these have energy demand that falls partly or fully outside the solar generation window. Without storage, that demand has to be met by the grid. With storage, it is met by solar electricity generated earlier in the day.

Benefit 2: Peak demand reduction and lower non-commodity charges

Non-commodity charges make up a significant and growing portion of commercial electricity bills. Distribution Use of System (DUoS) charges, Transmission Network Use of System (TNUoS) charges, and Triads are all linked, directly or indirectly, to the level of demand that a site places on the network during peak periods. For large commercial and industrial consumers on half-hourly metering, these charges can account for 30 to 40% of total electricity costs.

Battery storage enables peak shaving: the controlled discharge of stored energy during periods of highest demand. Rather than drawing from the grid at the moment demand peaks, the system draws from the battery instead. The peak on the meter is flattened. The charges linked to that peak are reduced.

The value of peak shaving depends on the site's demand profile and tariff structure, but for high-consumption businesses on complex commercial tariffs, it can be one of the most significant financial benefits of adding storage. It is also a benefit that does not depend on sunshine; the battery can charge from the grid overnight on cheap off-peak rates and discharge during expensive peak periods, independently of solar generation.

Benefit 3: Time-of-use tariff optimisation

Smart time-of-use tariffs, such as Octopus Agile for commercial accounts, apply dynamic pricing based on wholesale market conditions. The spread between off-peak and peak rates can be significant: off-peak rates can fall below 5p/kWh overnight, while peak rates can reach 35p/kWh or more during high-demand periods. Battery storage turns that spread into a financial opportunity.

Charge the battery overnight at cheap off-peak rates. Discharge during peak-rate periods instead of drawing from the grid. The saving per kWh is the difference between the two rates. Done consistently across a year, on a commercial-scale battery, this tariff arbitrage generates meaningful returns independently of what the solar panels are doing.

When combined with solar, the two systems reinforce each other. Solar charges the battery during the day. The battery tops up overnight when rates are low. Both feed into the building's load at the most expensive times. The combined system is using cheap electricity all day and avoiding expensive electricity throughout.

Benefit 4: Grid export limitation and network constraint resolution

Not every site can export freely. Distribution networks in many parts of the UK are constrained, and some DNOs restrict or cap the amount a commercial site can export. A G100 export limitation arrangement, for example, caps export at 16A per phase regardless of system size.

Battery storage resolves this constraint without reducing system size. Rather than curtailing generation when the export limit is reached, the system redirects excess generation into the battery instead of the grid. The solar panels keep producing. The energy is captured and used on-site later. The export cap is respected.

In practice, this means battery storage can allow a larger solar installation to be justified on constrained network sites where the DNO would otherwise limit how much can be connected. The solar array is sized for the building's consumption and storage capacity, not for what the network will accept as export. For businesses on industrial estates or in areas with known network constraints, this is a material project design advantage.

Benefit 5: Operational resilience and supply security

A standard grid-tied solar installation shuts down automatically if the grid goes down. This is a safety requirement: without it, the system could back-feed into a dead network and endanger engineers working on the lines. Panels generate nothing during a power cut, regardless of how much sun there is.

Battery storage systems with islanding capability change this. The storage system detects a grid outage and switches the site to island mode, drawing from the battery and continuing to accept solar generation. Essential loads, refrigeration, servers, production lines, security systems, stay live. The business continues to operate. For some sectors, cold storage in particular, even a short grid outage carries significant financial risk. Storage with islanding is insurance against that risk.

The value of this benefit is difficult to quantify in advance but easy to measure after an outage. Businesses that have experienced stock loss, production downtime, or data loss during grid interruptions tend to view it as one of the strongest arguments for storage.

Benefit 6: Measurable carbon reduction and ESG reporting

Commercial solar reduces a business's Scope 2 carbon emissions by replacing grid electricity with on-site renewable generation. Battery storage extends the reach of that displacement. A solar installation with storage replaces more grid electricity per panel-hour of generation than solar alone, because more of the generation is retained on-site and used in place of grid power.

The carbon intensity of grid electricity fluctuates significantly by time of day. It is typically highest during morning and evening peaks, when gas peaker plants are running, and lowest at midday when solar generation nationally is at its peak. Discharging a battery during the evening peak displaces high-carbon grid electricity. This improves the actual carbon reduction delivered relative to what the kWh figures alone would suggest.

For businesses subject to Streamlined Energy and Carbon Reporting (SECR), or those preparing Scope 2 disclosures for CDP, TCFD, or CSRD frameworks, the combination of solar and storage provides credible, auditable emissions reduction data. That data strengthens sustainability reports, supports net-zero commitments, and increasingly features in supplier qualification criteria from large corporate buyers.

Benefit 7: Future-proofing for grid changes and demand growth

The UK's electricity network is changing faster than at any point in the past decade. The National Energy System Operator (NESO) has published projections showing that battery storage capacity across the UK needs to scale significantly by 2030 to support clean power targets. Connection queues are long. Export constraints are spreading. Time-of-use pricing is becoming the default commercial tariff structure. All of these trends favour businesses that have storage in place.

Businesses planning to add electric vehicle charging infrastructure, heat pumps, or additional production lines in the next five years are also better positioned if storage is already installed. Adding significant electrical load to a site with batteries is more straightforward than adding it to a site with only solar: the storage can absorb demand peaks from the new load and prevent the site's import capacity from being exceeded.

According to Solar Energy UK, integrated storage is now a standard feature in over 50% of new commercial solar projects in the UK. The direction of travel is clear.

Solar only versus solar with battery storage: at a glance

Solar only	Solar with battery storage
Self-consumption: 40 to 55%	Self-consumption: 75 to 90%
Surplus generation exported at 3 to 15p/kWh	Surplus stored and used at full grid rate value (i.e. a saving of 25 to 28p/kWh)
No peak shaving capability	Peak shaving available: reduces demand charges
No tariff arbitrage	Overnight cheap-rate charging possible on time-of-use tariffs
System shuts down during grid outage	Island mode available for continued operation during outage
Export limited by DNO capacity	Excess generation directed to battery, not restricted by export cap
Lower upfront cost	Higher upfront cost, offset by wider range of savings streams
Faster payback period	Higher total return over system life (20+ years).

Which businesses benefit most from adding battery storage?

The combination of solar and storage is not right for every site at every point. For businesses with very high and consistent daytime consumption, solar alone already achieves strong self-consumption without storage. Adding batteries adds cost without proportionally improving returns.

Storage adds most value where at least one of the following applies:

• Operations extend beyond daylight hours. Evening, nightshift, or 24-hour businesses cannot fully use solar generation in real time. Storage bridges the gap.

• The site faces high non-commodity charges. Peak shaving directly reduces DUoS and Triads-linked costs.

• The network is constrained. Storage allows a larger solar array to be installed than the export limit alone would permit.

• Power continuity is critical. Cold storage, food production, pharmaceutical, and data-sensitive operations cannot accept unplanned outages.

• The business is on or moving to time-of-use tariffs. Tariff arbitrage compounds with self-consumption saving.

• ESG or net-zero commitments are material. Storage increases auditable carbon displacement relative to solar alone.

Cold storage and food production tend to see some of the strongest combined returns. High 24-hour electricity demand, zero tolerance for outages, and peak demand charges driven by refrigeration compressors all make the storage case compelling.

At Eden Sustainable, cold storage and food production clients consistently rank among those where storage adds the most measurable value.

What does adding battery storage cost, and is it better to install together or retrofit?

Commercial battery storage costs have fallen 30 to 40% since 2022, driven by expanding lithium-ion manufacturing capacity globally. In 2026, installed cost for a commercial system sits at approximately £200 to £450 per kWh, with a typical 100kWh system costing between £20,000 and £40,000 depending on chemistry, configuration and site specifics, according to GSL Energy's 2025 market analysis.

Installing solar and battery storage together is more cost-effective than doing them separately. A combined installation uses one scaffold, one DNO application, one commissioning event, and one set of electrical works. Splitting them across two projects adds cost to both.

It is also more efficient from a system design perspective. A hybrid inverter, specified at the outset, manages both solar generation and battery charging and discharging from a single unit. Retrofitting storage onto an existing solar system that was not designed for it often requires AC coupling, an additional inverter, and more complex commissioning. The result works, but it costs more and is less elegant.

If budget constraints mean a phased approach, the right move is to install a hybrid inverter and battery-ready design from day one, even if the battery itself follows later. The marginal cost of the hybrid inverter at the outset is small. Replacing a standard inverter later to accommodate storage is not.

How Eden Sustainable approaches solar and battery storage projects

We have been designing and installing commercial and industrial solar systems for over ten years, with more than 300 installations across manufacturing, logistics, food production, cold storage, commercial property and education. Battery storage has been part of our offer for several years, and the proportion of projects that include storage continues to grow.

Our starting point is always the client's consumption data. Half-hourly meter data tells us when demand peaks, how it varies across the week, and where the gaps between solar generation and site consumption are widest. That analysis determines whether storage adds value, what capacity is warranted, and how the system should be configured to maximise the combination of self-consumption saving, peak shaving, and tariff optimisation.

We do not recommend storage as a default addition to every project. Where the numbers support it, the case for storage tends to be clear and we make it in full. Where they do not, we say so.

The most useful thing we can do for a client is give them an accurate picture of what the combined system will actually deliver, not the best-case version of it.

Frequently asked questions

Can I add battery storage to an existing commercial solar installation?

Yes. Battery storage can be retrofitted to an existing system via AC coupling, where a separate battery inverter sits alongside the existing solar inverter. The main considerations are whether the existing inverter can communicate with the battery management system, what the available space is for battery units, and whether a G99 application update is required if the total system capacity changes. Retrofitting costs more per kWh of storage than installing storage as part of the original project, because the electrical and commissioning work must be done as a separate event.

How long does a commercial battery storage system last?

Lithium iron phosphate (LFP) batteries, now the most common chemistry for commercial BESS in the UK, typically carry a 10-year performance warranty and a useful life of 15 years or more with appropriate battery management. Lithium-ion NMC chemistry, still used in some systems, degrades at approximately 2 to 3% capacity per year. At the design stage, degradation should be factored into the storage sizing so the system still meets its targets in year ten, not just year one.

Does adding battery storage affect the G99 grid connection application?

Yes, in most cases. Under G99 Issue 2, which was updated in March 2025, battery storage systems with grid export capability are now subject to mandatory inclusion in the G99 application. If you are adding storage to an existing installation, the DNO will likely require an updated application. If you are designing a new system with storage from the outset, the G99 application covers both. Your installer should handle both the application and the DNO liaison as part of the project.

What size battery does a commercial business need?

Sizing depends on three things: how much surplus solar generation the site produces that would otherwise be exported; the pattern and timing of demand that falls outside the solar generation window; and whether the primary use case is self-consumption, peak shaving, or both. A cold storage site with 24-hour demand and a large roof array needs more storage than an office building that closes at 6pm. As a starting point, half-hourly consumption data for the past 12 months and the proposed solar system design are the inputs any competent installer should use. Rules of thumb about kWh per kWp are not reliable enough for commercial system sizing.

Is the investment in commercial battery storage eligible for any tax relief?

Yes. Commercial battery storage systems qualify for the Annual Investment Allowance (AIA), which allows businesses to write off the full capital cost against taxable profits in the year of installation. At 25% corporation tax, a £30,000 battery system generates up to £7,500 in tax relief in year one, reducing the effective net cost to £22,500. Where the battery is installed alongside solar panels, both systems qualify and the combined capital allowance can be material. VAT at 20% applies to the installation and is reclaimable by VAT-registered businesses. You should confirm the specifics with your accountant.

What happens to surplus solar generation if the battery is full?

Any generation that exceeds both on-site demand and battery capacity is automatically exported to the grid under the Smart Export Guarantee (SEG), provided you have a SEG contract in place with an eligible supplier. Commercial SEG rates currently range from 3p to 15p per kWh, with higher rates available on time-of-use tariffs. Export income is real and should be included in financial modelling, but it is worth significantly less per unit than self-consumption saving at current commercial grid rates.

Find out what solar and storage could deliver for your site

If you are assessing whether battery storage makes sense alongside a commercial solar installation, we can model the combined return for your specific site using your half-hourly consumption data. The analysis covers self-consumption improvement, peak shaving value, tariff optimisation, and carbon reduction, set against the installed cost and payback timeline.

Contact Eden Sustainable at edensustainable.co.uk or call us to speak with a member of our commercial team.