Battery Storage Installation

What a battery changes

Solar without storage has an awkward shape. Generation peaks in the middle of the day; household consumption peaks in the evening. If nobody is home between eight and six, most of what the array makes is exported at a low rate and bought back a few hours later at a high one.

A battery closes that gap. It stores what the house is not using and gives it back when the house needs it. That is the entire proposition, and it is why storage often improves the economics of a solar system more than adding another two kilowatts of panels would.

AC-coupled or DC-coupled

There are two ways to connect a battery, and the right answer depends on whether the solar already exists.

DC-coupled puts the battery on the same side as the panels, through a hybrid inverter that manages both. It is more efficient because the energy is converted once rather than twice, and it is the natural choice when solar and storage are installed together.

AC-coupled puts the battery on the house side with its own inverter. It is less efficient, but it does not care what solar system is already there, which makes it the usual answer for a retrofit onto an existing array.

Sizing it properly

The most common mistake in battery specification is buying capacity that never gets used. A battery only earns its keep when it cycles — filling and emptying most days. Oversize it and you have paid for kilowatt-hours that sit idle.

We look at three things:

1. Evening and overnight consumption. What the house actually uses between the sun going down and coming back up.
2. Surplus generation. What the array produces beyond what is being consumed at the time.
3. Tariff. On a time-of-use tariff, capacity can be filled cheaply overnight regardless of the weather, which changes the sizing considerably — and makes storage worthwhile even in December.

Power output matters as much as capacity. A battery with 10kWh of capacity but only 3kW of continuous output cannot run a shower, an oven and an EV charger at once. Capacity is how much; power is how fast.

Siting

Batteries do not like heat, and they do not like being difficult to reach. A loft is the worst of both — it is the hottest part of the house in summer and nobody wants to service equipment through a hatch. Where there is any alternative, we use it: a garage, a utility space, or an external wall in a weatherproof enclosure.

Siting also covers ventilation, clearances specified by the manufacturer, distance from escape routes, and the practicalities of getting a heavy unit into position in the first place.

Charging from a tariff

Time-of-use tariffs price electricity by the half hour. Charge the battery when the rate is low and discharge it when the rate is high, and the price differential alone pays something back — before the solar contributes anything. This is why a battery can be worth installing in a house with no solar at all, and why we ask about your tariff during the design rather than after commissioning.