Behind-the-meter (BTM)
A battery installed on the customer's side of the utility meter - a customer asset rather than a grid asset.
A behind-the-meter (BTM) battery sits on the customer's side of the utility meter. It's part of the customer's site infrastructure, alongside their UPS, HVAC, and production loads.
BTM batteries reduce the customer's electricity bill through peak shaving and tariff optimisation, and can participate in market services with their spare capacity - but their primary purpose is to serve the customer's site.
Contrast with a front-of-meter battery, which sits on the grid side of the meter, has its own connection point, and exists purely to make money in wholesale and ancillary services markets.
BTM batteries include UPS installations, BESS on industrial sites, and rooftop-solar-plus-storage.