A 20kW solar system with battery storage is often the point where solar starts to feel like a serious business decision rather than a “nice idea”. It’s large enough to deliver meaningful savings, flexible enough to suit different types of sites, and adaptable as energy needs change.
The challenge is that there isn’t one standard setup that works for everyone. The way a site uses power, when demand peaks, and how much solar is exported all play a role in shaping the right solution.
This list looks at five proven ways to design a 20kW solar system with battery storage for UK projects. Each approach is based on how these systems are typically used in the real world, not just how they look on a spec sheet.
1. The balanced all-rounder system
Why it’s on the list
This is the most common route for good reason. A balanced system pairs a 20kW solar array with a sensibly sized battery so you can store surplus generation and use it later, without overspending upfront. It’s practical, flexible, and suits a wide range of sites.
Key highlights
- Designed to capture a meaningful amount of daytime solar.
- Keeps the system simple while still delivering noticeable savings.
Best for
- Offices, light industrial units, and retail sites with steady daytime use.
- Businesses that want a strong return without overcomplicating the design.
Watch-outs
- If your demand spikes sharply, capacity alone may not solve the problem.
- Export limits can reduce the value of storage if not factored in early.
Typical system set-up
Most systems of this type use battery capacity in the region of 40–60kWh, sized around real half-hourly data rather than estimates. Clear monitoring is essential so performance can be reviewed and adjusted over time.
Questions worth asking early
Before committing, it’s worth checking whether the system is being designed around how your site actually behaves.
- Has the battery size been modelled using half-hourly data, not assumptions?
- Can the system be adjusted later if your usage pattern changes?
2. The peak-shaving focused system
Why it’s on the list
Some businesses don’t struggle with overall usage — they struggle with short, expensive peaks. This approach focuses less on storing lots of energy and more on delivering power when demand suddenly jumps.
Key highlights
- Designed to discharge strongly during known peak periods.
- Prioritises power output rather than maximum storage capacity.
Best for
- Gyms, workshops, hospitality venues, and cold storage.
- Sites where peak charges make up a large part of the bill.
Watch-outs
- Savings depend on how predictable your peaks are.
- Poor control settings can drain the battery before it’s actually needed.
Typical system set-up
These systems often use 30–50kWh batteries with higher discharge capability, paired with controls that target specific times of day rather than running continuously.
Questions worth asking early
Peak-shaving only works if the battery is doing the right thing at the right time.
- Which specific peaks is the battery being set up to reduce?
- How will the controls prevent the battery from discharging too early?
3. The backup-ready system
Why it’s on the list
For some businesses, continuity matters just as much as cost. A battery can be designed to keep essential loads running during an outage — but only if the system is set up correctly.
Key highlights
- Supports critical circuits during grid interruptions.
- Can reserve charge specifically for backup use.
Best for
- Healthcare settings, food businesses, and security-sensitive sites.
- Any operation where downtime quickly becomes expensive.
Watch-outs
- Not all solar and battery systems provide true backup by default.
- Backup capability adds design and installation complexity.
Typical system set-up
This approach usually includes a separate essential-loads board and battery settings that protect a portion of charge for emergencies, rather than using every kilowatt-hour for daily savings.
Questions worth asking early
Backup expectations should be crystal clear from the start.
- Which loads will stay powered during an outage — and which won’t?
- How much battery charge will be reserved purely for backup?
4. The solar-maximising system
Why it’s on the list
If your site regularly exports large amounts of solar, a bigger battery can help you keep more of that energy on site and use it later, when it’s actually valuable.
Key highlights
- Reduces reliance on low-value export.
- Extends the benefit of solar into evenings and longer operating hours.
Best for
- Sites with strong solar generation but lower daytime demand.
- Businesses operating into the evening or with overnight baseload.
Watch-outs
- Bigger batteries only pay off if surplus is consistent.
- Space and fire strategy planning become more important.
Typical system set-up
Battery capacity often sits in the 60–100kWh range, sized after reviewing current export levels. Many sites start smaller and expand once performance is proven.
Questions worth asking early
Larger batteries should be justified with real data, not optimism.
- How much energy is your site currently exporting on a typical day?
- Would a phased approach deliver better value than installing everything upfront?
5. The future-proof modular system
Why it’s on the list
Energy use rarely stays still. This approach allows you to start with a sensible 20kW system and add more storage later as your business grows.
Key highlights
- Modular battery design allows staged expansion.
- Helps spread investment over time.
Best for
- Growing businesses and multi-tenant sites.
- Locations planning EV chargers, new equipment, or longer hours.
Watch-outs
- Expansion only works if it’s planned from the start.
- Future grid permissions can affect what you’re allowed to add.
Typical system set-up
These systems are designed with extra space, cabling capacity, and monitoring headroom from day one, so adding batteries later doesn’t mean redesigning the whole installation.
Questions worth asking early
Future-proofing only works if it’s designed in, not promised later.
- Is there enough space and electrical capacity for additional batteries?
- Could grid or export limits restrict future expansion?
How We Decided Which 20kW Systems Made the List
What we looked at | Why it matters in the real world |
| How a 20kW site really uses energy | A 20kW system can serve very different sites. We looked at load patterns, peak times, and operating hours, not just total annual usage. |
| How well solar and the battery work together | The system has to do more than just generate power. We focused on setups that store surplus solar and use it later, when grid electricity costs more. |
| Ability to control peaks | For many businesses, short bursts of high demand are expensive. We prioritised system approaches that can reduce those peaks, not just store energy. |
| Room to adapt over time | Energy use changes. We favoured systems that can be adjusted or expanded without starting from scratch. |
| Practical installation | We considered space, access, and layout — the things that often cause issues on real UK sites if they’re ignored early. |
| Suitability for UK rules and conditions | Grid permissions, export limits, and UK tariffs matter. The systems on this list reflect what’s realistic in the UK, not idealised examples. |
The Bottom Line
A well-designed 20kW solar system with battery storage can help a business use more of its own energy, reduce exposure to peak costs, and gain better control over electricity spend — but only if it’s tailored to the site it’s serving.
There’s no one-size-fits-all answer. The right setup depends on how your business operates today and how it’s likely to change over time.
If you’re considering a 20kW system and want clear, practical advice on what would actually work for your site, contact Perfect Sense Energy. Their team can assess your energy use, model the benefits, and design a system that fits your business — not the other way round.
FAQs
What is a 20kW solar system with battery storage?
A 20kW solar system with battery storage combines a medium-scale solar array with a battery that stores surplus electricity for later use.
It allows businesses to use more of their own solar power, reduce reliance on the grid, and manage energy costs more effectively.
Is a 20kW solar system suitable for UK businesses?
Yes, a 20kW solar system is suitable for many UK businesses with moderate to high electricity use.
It works particularly well for offices, light industrial units, retail sites, and mixed-use buildings that operate mainly during the day.
How much battery storage should be paired with a 20kW solar system?
The right battery size for a 20kW solar system depends on how and when the site uses electricity.
In many cases, batteries in the 40–60kWh range are used initially, with capacity adjusted based on half-hourly usage data.
Can a 20kW solar system with battery storage reduce electricity bills?
Yes, a 20kW solar system with battery storage can reduce electricity bills by increasing self-consumption and lowering peak grid imports.
Savings depend on usage patterns, tariffs, and how well the system is designed and controlled.
Do I need permission to install a 20kW solar system with battery storage in the UK?
Some installations require permission, but many do not.
Planning and grid approval depend on factors such as location, building type, export limits, and battery placement, so this should always be checked early.
