Helpful video reference. Artisan Electrics covers battery installation quality points in "How to make your battery installations better". The channel has produced trade-focused content on solar and battery work for UK electricians, and this video addresses several of the common installation errors that appear at inspection. Useful for anyone planning or reviewing a battery installation.
1. Choose the right battery type and capacity
Most residential battery storage systems use either lithium iron phosphate (LFP) or nickel manganese cobalt (NMC) chemistry. LFP cells are the safer option for indoor domestic installations: they run cooler under load, are more thermally stable, and have a longer rated cycle life than NMC. NMC cells offer higher energy density in a smaller package but are less forgiving of temperature extremes and overcharging.
Size the battery to what you will actually use, not to the maximum your solar system can generate. In a typical UK household, the useful overnight storage requirement is 5-10kWh. A larger battery than this may never fully discharge in winter months, which reduces effective cycle count and return on investment.
2. Select a suitable installation location
The installation location must satisfy several requirements simultaneously: within the manufacturer temperature range, accessible for maintenance, away from escape routes and sleeping areas, and separated from gas appliances and gas meters. Most wall-mounted lithium batteries are rated for indoor installation and are not suitable for installation in an unheated garage in the UK climate without checking the manufacturer's minimum temperature specification.
Plan the cable routes from the installation location to the inverter and to the consumer unit at this stage. Long DC cable runs increase resistive losses and may require a larger cable cross-section to compensate. The inverter should ideally be mounted close to the battery to keep DC cable lengths short.
3. Ventilation and thermal management
Lithium batteries generate heat during charge and discharge cycles. Most wall-mounted residential batteries are designed to dissipate this heat by convection to the surrounding air, which means the manufacturer minimum clearances around the unit are not merely advisory: they are required for safe operation.
In a utility cupboard or confined space, check whether the accumulated heat from the battery plus the inverter creates an environment that exceeds the maximum ambient temperature specification. If it does, forced ventilation is needed. Some battery systems include an internal cooling fan; check whether this creates noise that would be intrusive in an adjacent living space.
4. Size DC cables correctly
DC cables between the battery and the inverter carry current at the battery voltage, typically 48V to 100V DC for residential systems. At these voltages, the current for a given power level is much higher than on the AC side. A 5kW inverter operating at 50V DC draws 100A. The DC cables must be rated for this current, and the cable cross-section must keep resistive losses and temperature rise within acceptable limits.
Use dedicated DC solar or battery cable, not standard twin and earth. DC cable is double-insulated, tinned for corrosion resistance, and rated for the DC voltage of the system. Fit DC fuses or a DC isolator close to the battery terminals on both positive and negative conductors, sized to the maximum charge and discharge current of the battery.
5. Earth and bond the installation
Connect the battery enclosure, the inverter enclosure, and all accessible metalwork associated with the system to the main earthing terminal of the installation. In a TN-S or TN-C-S (PME) system, this means connection to the earth bar in the consumer unit.
DC earthing arrangements vary between inverter designs. Some hybrid inverters earth the DC negative at the inverter; others use a floating DC bus. Follow the inverter manufacturer wiring diagram for the specific model. Do not earth the DC negative at more than one point in a floating system, as this creates a path for circulating currents that can cause nuisance tripping of protection devices.
6. DNO notification: G99 and G100
If the battery system can export energy to the grid, either directly or via a solar PV system, DNO notification is required before the system is energised. The two applicable engineering recommendations are:
- G100: For systems exporting up to 3.68kW per phase on a single-phase connection. This is a simplified notification process. The DNO must be informed but does not typically withhold approval for a standard domestic system.
- G99: For systems above the G100 threshold, three-phase systems, or batteries being added to an existing solar installation that already notified under G99. G99 requires a formal application, and the DNO has up to 45 working days to respond. Do not energise the system until approval is received.
The installer, not the homeowner, is responsible for submitting the correct notification. Check which process applies before ordering equipment, as a G99 application can significantly delay commissioning.
7. Commission and update firmware
Follow the manufacturer commissioning procedure exactly. Incorrect settings - particularly for grid protection thresholds, charge and discharge rates, and battery management system parameters - can cause the system to operate outside safe limits or fail the grid protection tests required by G99 or G100.
Check for pending firmware updates immediately after initial setup and before leaving the system running. Battery manufacturers regularly release firmware updates that modify protection behaviour, improve compatibility with grid protection requirements, and correct faults identified in the field. Many battery warranties require the firmware to be kept current.
8. Annual maintenance
Carry out an annual inspection of the complete installation. This should cover:
- Visual inspection of all DC cable terminations for signs of heat discolouration, corrosion, or loosening
- Operation check of all DC isolator switches
- Confirmation that ventilation paths around the battery and inverter are clear
- Review of system performance data for deviations from expected charge and discharge patterns
- Earth continuity check on all bonding connections
- Firmware version check and update if required
A battery system showing significantly reduced capacity compared to its rated output warrants investigation. Natural degradation is expected over the system life, but a sudden reduction in usable capacity can indicate a cell group failure that the battery management system may not report clearly.
When to call us
Richard inspects, tests, and certifies home battery storage installations, and can diagnose faults on existing systems that are underperforming. Covers Sandwich CT13 and surrounding east Kent.
Battery storage inspection in east Kent?
Richard inspects, tests, and certifies home battery storage installations, and can diagnose faults on existing systems that are underperforming. Covers Sandwich CT13 and surrounding east Kent.
Contact Richard