A solar array can produce its highest output at midday, just as a home is empty or a business is operating at a lower load. Battery storage changes that pattern. Instead of sending every unused unit back to the grid, a suitably designed system stores some of that electricity for use later, when demand and electricity prices are often higher.
For homeowners, landlords and businesses, this can be an effective way to gain more value from solar PV and reduce reliance on imported electricity. It is not, however, a one-size-fits-all purchase. The right system depends on how the property uses energy, the condition of the electrical installation, the tariff in place and what you expect the battery to achieve.
What battery storage does
A battery stores electricity as direct current (DC). An inverter manages that stored energy and supplies it to the property in a form that can be used by normal electrical circuits. Where solar PV is fitted, the system can charge from surplus generation during daylight and discharge when the building needs power later in the day.
Some systems can also charge from the grid during cheaper off-peak periods, then supply power during more expensive periods. This can be useful in a property without solar, but the financial case needs to be based on real tariff prices and household or business demand, rather than headline savings claims.
Most installations are designed to reduce imported electricity rather than make a property independent from the grid. A battery has a finite capacity and output. On a dark winter evening, when heating, cooking, lighting and appliance use overlap, a modest domestic battery can discharge quickly. For commercial sites, the gap between a small battery and a large operational load can be greater still.
Battery storage and solar PV
Solar and battery storage work well together because they address the timing problem of generation. Without a battery, a property may use solar electricity as it is generated but export the remainder. With storage, more of that generation can be retained for evening use.
The benefit depends on daytime consumption. A home with occupants working from home may already use a significant share of its solar output. A shop, office or workshop that operates through daylight hours may do the same. In these cases, a battery can still help, but it may be smaller than one selected for a property that is largely empty during the day.
For a business, battery capacity must be considered alongside operating patterns. Refrigeration, IT equipment, lighting, machinery and EV charging can create very different load profiles. A detailed review of half-hourly data, where available, provides a much better starting point than simply matching battery capacity to the size of the solar array.
New solar installations and retrofits
A battery can be installed with a new solar PV system or added later. New installations are often simpler to design as the inverter arrangement, cable routes, protective devices and export settings can be planned together.
A retrofit battery may be AC-coupled, meaning it has its own inverter and connects to the property’s AC electrical system. Alternatively, a DC-coupled arrangement may share equipment with solar PV. Neither option is automatically better. Existing solar equipment, available space, budget, warranty requirements and future expansion plans all affect the right choice.
Sizing a battery properly
Choosing the largest battery available is rarely the most sensible route. An oversized battery may spend much of the year partly charged because there is not enough solar surplus or cheap overnight electricity to fill it. An undersized battery may fill early but have little energy left for the evening peak.
A professional assessment should look at four connected factors:
- electricity consumption across a typical day, including seasonal changes;
- solar generation and the amount likely to be exported;
- the battery’s usable capacity and maximum discharge rate; and
- the property’s tariff, future plans and budget.
Usable capacity matters because manufacturers may state a total capacity that is higher than the energy intended for regular use. The battery’s discharge rate also matters. A system may hold enough energy in theory but be unable to supply every high-load appliance at once. Kettles, ovens, immersion heaters, electric showers and heat pumps can create short periods of substantial demand.
For commercial premises, it is also worth checking whether the objective is energy shifting, reducing peak demand, providing limited resilience, or a combination of these. A battery designed to support a controlled evening load is different from one intended to reduce short, sharp demand peaks from equipment starting up.
Can a battery keep the power on in a cut?
Not always. Many grid-connected battery systems shut down during a power cut to protect electricity network workers. This is normal and should not be mistaken for a fault.
If backup power is required, it needs to be specified at the design stage. Some systems can supply selected essential circuits through a backup or EPS output, such as lighting, broadband, refrigeration or certain socket circuits. Others can provide wider backup, subject to the system design and the available battery output.
Whole-property backup is more complex. It must account for large loads, starting currents and the risk of draining the battery quickly. In many cases, supplying a carefully selected essential-load consumer unit is the safer and more cost-effective solution. Critical equipment in commercial settings may also need a separate resilience strategy rather than relying on a general-purpose battery alone.
Electrical safety, approval and installation standards
Battery storage is not a fit-and-forget appliance. It is an electrical installation that must be designed, installed, tested and commissioned correctly. The existing consumer unit, earthing arrangement, main supply, protective devices and available capacity all need assessment before work begins.
The installation location is equally important. Batteries must be mounted and protected in line with the manufacturer’s instructions and applicable standards. Access, heat, impact risk, cable routes, ventilation requirements and safe isolation all need consideration. A garage, utility room or external location may be suitable in some properties, but the right answer depends on the equipment and the building.
Where a system can export electricity to the network, the installation must meet the relevant connection requirements. Depending on the equipment and export capacity, this may involve G98 notification or a G99 application with the local Distribution Network Operator. These steps are not paperwork to leave until the end. They can affect the equipment selected, export settings and installation programme.
For landlords and property managers, any battery installation should form part of the wider electrical safety picture. Keep commissioning records, certificates, operating information and maintenance documentation with the property’s electrical records. If an EICR is due, tell the inspector about the solar and battery equipment so it can be considered properly.
What affects the return on investment?
Savings come from avoiding some imported electricity, using more self-generated solar power and, where appropriate, shifting electricity use away from expensive tariff periods. The value of each stored unit depends on the difference between the price of imported electricity and the value of electricity that would otherwise be exported.
That means results vary. A property with high evening usage, a suitable time-of-use tariff and regular solar surplus may see a stronger return than one with low annual consumption and little spare generation. Electricity prices, export rates, battery degradation and tariff changes also influence long-term performance.
Businesses should be cautious about simple payback figures that do not reflect their actual operating hours. A battery can support cost control, but it should be assessed alongside efficiency measures such as LED lighting, controls, efficient equipment and solar generation. Reducing avoidable demand first can reduce the size of the system needed.
Questions to ask before going ahead
Before approving a battery storage installation, ask what capacity is usable, how much power it can deliver at one time, whether backup is included, and which circuits would operate during an outage. Confirm how the system will interact with solar PV, the grid tariff and any future EV charger or heat pump.
It is also sensible to ask who will handle network notifications, what certificates will be provided, how monitoring works and what maintenance or warranty conditions apply. Clear answers at this stage prevent costly assumptions later.
For properties across Hull, East Yorkshire and Lincolnshire, Steel Electrical Services Ltd can assess the existing installation, energy requirements and practical options before recommending a system. Honest advice matters: battery storage should support the way you use electricity, not force your property to fit a standard package.
A well-designed battery will be safe, correctly connected and sized around real usage. Start with your electricity data and the condition of your electrical installation, then choose a system that gives useful control over energy costs without promising more than it can deliver.
