£1500 battery cos / 25000kWh life time storage at 50% discharge cycles for 838Ah battery = 6p / kWh
additional cost of inverter and batteries and fitting = approx £3500 / 25000kWh = 14p /kWh
Anyone who thinks electricity is going to cost less than 14p per kWh on average over the coming decade is in for a disappointing time of it.
Yes there are losses in the battery charge / discharge cycle and storage, so they need to be minimised by careful selection of batteries, and limiting the proportional rate of charging and discharging, but the economies are beginning to stack up in certain niche situations IMO, and this will only continue to improve as electricity prices rise..
The big potential for it though is if the grid connection limits are viewed as export limits rather than generation limits, as it means that bigger systems can be installed, allowing for more generation in total, without ending up exporting more than 16amps to the grid. This is a debatable point at the moment, but it has to happen if the UK is to get anywhere close to the higher level of PV saturation required to hit targets / minimise the climate impact. This will also greatly help with grid balancing, as it allows solar generation to be used to feed in to the evening consumption peak.
Why isn't the world storing solar energy in huge battery farms?
because that would be trying to replace energy at the grid side of the meters, which is charged at much lower rates than households pay themselves, so the economics stack up (just about) at a household scale, but not on the grid side of things in most cases, unless it's a cheaper way of balancing the local grid than eg installing a bigger transformer / cables.
Basically we're now at the tipping point where it's starting to make economic sense in some situations, and this will only improve from now on.
