Battery Energy Storage (BESS).

A UPS battery sits idle waiting for grid failure; a BESS is sized larger and controlled to discharge during peak-tariff hours, absorb solar and provide backup — same chemistry, three shifts. A UPS battery exists to bridge the gap between mains failure and generator startup; it sits idle the rest of the time. A BESS is sized larger and controlled by a smarter inverter that allows it to discharge into the building during peak-tariff hours, absorb surplus solar, and provide grid services in addition to backup. The same lithium chemistry can do both jobs in a hybrid topology — that's what we mean by 'three shifts'.

It depends on tariff exposure and topology, not a published figure. Buildings with significant peak-demand charges and a good peak/off-peak tariff spread see the fastest return from peak-shaving; where rooftop solar export tariff is poor, self-consumption is the stronger case; mission-critical hybrid topology (where the BESS is also the UPS battery) builds the case on lifetime-cost displacement of VRLA rather than tariff arbitrage. We model your tariff exposure and load profile and share the commercial case — including an indicative payback — in a written estimate after review.

Specify LFP (lithium iron phosphate) for stationary BESS — better thermal stability, longer cycle life, more tolerance of deep discharge, lower fire risk. NMC (nickel manganese cobalt) has higher energy density per kg and is appropriate only where weight or footprint is critical and operating temperature is controlled. For 95% of the buildings we engineer, LFP is the right answer.

An LFP BESS lasts 16+ years cycled once daily for peak-shave or 8–10 years cycled twice daily for arbitrage — 6,000+ cycles at 1C discharge to 80% retained capacity. We specify and warranty against actual usage profile, not against an idealised cycle count.

Yes for short windows; continuous off-grid operation needs solar generation exceeding daily consumption plus a BESS sized for night-time — that's microgrid territory, and we engineer it where the location and economics support it. Sizing the BESS to building-level autonomy is what 'mission-critical' deployments do.

BESS AMC includes quarterly cell-bank impedance and temperature-trend reviews, annual capacity tests, BMS firmware management, balancing-routine verification and an integration health-check with the building's BMS, plus a spare-cell and BMS-board pool for active deployments. Response targets are written into the contract.

Yes — and the pairing is usually the point. The BESS rides through short outages and shaves peaks silently and instantly, while the diesel set remains the long-duration backstop; the control logic decides when each runs. Done well, the generator starts less often, runs closer to its efficient load band, and the building stops living with the start-up gap.

Chemistry choice comes first — LFP is specified for stationary systems largely for its thermal stability. Around it sit a battery-management system supervising every cell's voltage and temperature, an enclosure or room with designed ventilation and thermal management, coordination with the building's fire-detection scope, and a written response procedure. These belong in the design stage, not the handover punch list.

Solar generates when the sun decides; the battery shifts that energy to when the building needs it. Where the export arrangement pays poorly, storing surplus generation for the evening peak is worth more than exporting it, and the same capacity doubles as ride-through when the grid drops. Whether the case works depends on your tariff and load profile, which is why we model both before writing an estimate.