Storage Systems

Battery storage systems and expansion modules

Battery storage turns a solar array from a daytime generator into an around-the-clock energy system — storing surplus generation for the evening, charging on cheap overnight tariffs and providing backup where specified. We stock complete storage packages, self-consumption bundles and individual battery modules from Fox ESS, Pylontech, Sunsynk, Sigenergy, Huawei and other leading brands, at trade prices with live UK stock.

High-voltage stacks vs low-voltage batteries

Low-voltage (48V-class) batteries such as classic rack-mount modules remain a flexible, widely compatible choice and parallel easily for capacity. High-voltage stacked systems — where modules connect in series under a master control unit — operate more efficiently at higher power and dominate new residential and commercial specifications. High-voltage stacks are ecosystem products: the modules, control unit and inverter must come from matched, approved combinations, so always confirm compatibility before mixing components. Product pages state the required master units, minimum module counts and compatible inverters.

Chemistry, capacity and depth of discharge

Virtually everything we stock uses lithium iron phosphate (LiFePO4) chemistry, chosen across the industry for its thermal stability, long cycle life and high usable depth of discharge. When comparing systems, look at usable capacity rather than nominal capacity, the continuous charge/discharge rating in kW (which determines how quickly the battery can absorb surplus solar or cover an evening load), and cycle warranty terms. Most households pair storage in the 5kWh to 15kWh range with their array; commercial and heat-pump-heavy properties often specify considerably more, which is where stackable systems earn their keep — capacity can be extended module by module as requirements grow.

Packages and expansion

Our self-consumption and storage packages bundle matched inverters and batteries at package pricing, taking the compatibility question off the table. If you are extending an existing system, check the maximum module count and firmware requirements for your control unit, and note that some manufacturers require batteries within a stack to be of similar age. The System Builder sizes storage against your usage and array in about a minute.

Tariffs, backup and getting the most from storage

Storage economics improved sharply with time-of-use tariffs: charging overnight at off-peak rates and discharging through the day often pays back faster than solar-only self-consumption, and several battery ecosystems now integrate directly with smart tariff platforms to automate the cycle. If backup during a power cut matters, check the specification carefully — backup requires an inverter with EPS or backup output, appropriate wiring of protected circuits and, on many systems, an additional changeover accessory, and switchover behaviour differs between whole-home and essential-circuit designs. Product pages state EPS capability where it exists, and our team can confirm what a given inverter and battery pairing supports before you order.