Applications & Engineering

BESS Temperature Derating: Specify Power at Your Site

Compare the published temperature limits of HUA-X PowerFac-261 and PowerFac-5M, then request the output curves, site assumptions and auxiliary-load evidence your BESS quote needs.

By HUA-X · Published October 10, 2026

HUA-X PowerFac-261 cabinet in a sunlit industrial courtyard — An outdoor battery cabinet in an industrial courtyard.

A battery energy storage system's operating-temperature range does not establish full rated output at every temperature in that range. For a site-specific quote, request the available charge and discharge power, usable energy and auxiliary consumption at the conditions when the site needs the battery. HUA-X PowerFac-261 illustrates the distinction: its published information lists a −20 to 55°C operating range and output derating above 45°C. [1]

The procurement decision is whether the offered system can sustain the required duty through the relevant weather conditions. Compare your site requirements with the configuration-specific output curves and thermal-control requirements before accepting the offer.

Compare the operating-temperature limits

Operating-temperature limits for PowerFac-261 and PowerFac-5M. [1] [2]
Product	Operating-temperature range	Details to confirm for your site
PowerFac-261 — 125 kW / 261 kWh	Operating temperature: −20 to 55°C; output derating above 45°C. Liquid cooling. [1]	Configuration-specific charge/discharge limits versus temperature, with the temperature measurement point and duty conditions identified.
PowerFac-5M — 5,016 kWh battery container	Operating temperature: −20 to 50°C. Liquid cooling. [2]	Battery-side power limits and the proposed PCS limits, then the resulting performance at the agreed AC connection.

For PowerFac-261, request the available charge and discharge power above 45°C for your required duty cycle. Review the PowerFac-261 product and brief, or request PowerFac-261 technical documents for the configuration under discussion.

PowerFac-5M is a DC-side battery container; its energy rating does not establish the AC power of a complete project. Check the battery limits together with the selected PCS and auxiliary supply. [2] Review the PowerFac-5M scope and request its technical documents.

Keep ambient, enclosure and battery temperatures distinct

The outdoor air temperature, the air inside an enclosure and the battery temperature are different quantities. Ask the supplier which temperature each curve or limit uses, where it is measured and whether the result assumes steady operation or a short test. A weather record cannot be substituted directly for a measured cell temperature.

The National Laboratory of the Rockies identifies temperature and temperature uniformity as factors affecting battery performance and life, and assesses thermal behavior from cells to full systems. Ask for performance data for the complete system, including its thermal controls, at the temperatures relevant to your site. [3]

Engineer reviewing a tablet beside a weather observation mast in an industrial courtyard — Reviewing weather inputs at an industrial site.

Match weather records to the hours of required output

Send the project location and altitude, the available temperature records and the times when charging or discharging is required. Identify the source, measurement interval and period covered by the weather data. For a peak-shaving project, pair those timestamps with the load data; for backup, state the required duty and reserve. Ask the engineer to identify the design conditions used in the offer rather than relying on an annual average.

Site inputs and supplier responses for a temperature-specific BESS proposal.
Project input	Response to request	Why it matters to the buyer
Location, altitude and temperature records	Named design conditions, measurement basis and applicable temperature/altitude curves	Makes the operating assumptions visible before comparing proposals.
Required charge/discharge profile and duration	Available power and usable energy across the requested duty, with SOC and other limits stated	Shows whether a nameplate rating meets the actual operating requirement.
Equipment layout and proposed configuration	Confirmed cooling arrangement, installation constraints and included auxiliary equipment	Connects the performance response to the equipment and site being quoted.
Cooling, heating, pumps and other auxiliary loads	Power/energy consumption, supply source and agreed measurement boundary	Prevents consumption outside a quoted battery figure from disappearing from the site energy balance.
Required evidence and acceptance conditions	Applicable test report or engineering assessment, assumptions, remaining gaps and verification responsibility	Separates demonstrated performance from a calculation or an unverified allowance.

PowerFac-261’s altitude rating is 2,000 m, with derated operation from 2,000 to 4,000 m. If your site combines high temperatures and high altitude, request the available charge and discharge power for those combined conditions. [1]

Include cooling and heating in the energy balance

SAM’s battery thermal documentation distinguishes the battery environment from the battery temperature calculated by the model. For a conditioned space, it instructs users to account for heating or cooling power under battery losses; the thermal model does not explicitly simulate that equipment. A modeled result therefore depends on the temperature and auxiliary assumptions supplied to it. [4]

Apply that distinction when reviewing a quote: identify whether auxiliary power comes from inside or outside the quoted measurement boundary and ask how it was counted. Do not subtract the same auxiliary consumption twice. The round-trip efficiency guide explains why the measurement point must be stated when comparing energy results.

A research example: climate changed the modeled storage requirement

In an October 2021 Sandia study, researchers ran annual simulations of a warehouse application across eight US locations, including Fairbanks and Boston. The study coupled battery dispatch with enclosure heating and cooling. It used NMC lithium-ion cells and assumed battery temperature equaled enclosure temperature. [5] (pp. 8–9)

In the simulations, locations with extreme winters required larger storage systems when enclosure HVAC loads were included. These cold-climate results show why auxiliary loads need to be considered alongside the site’s required battery output. Include heating and cooling demand in the operating profile used to assess storage requirements. [5] (p. 13)

Engineers reviewing a site layout and notes at a project meeting table — Reviewing site conditions and the proposed equipment scope.

Make the temperature response part of the accepted scope

Ask the proposal to identify the exact product configuration, the controlled document revision, the curve or test evidence used and the conditions attached to the offered output. If the answer is based on calculation, request its inputs and assumptions. If evidence is still missing, keep the point open in the quotation review; an operating-temperature range is not a substitute for it.

Agree how the temperature-related performance claim will be verified before accepting equipment. A site test carried out in mild weather should not be described as a demonstration of performance at a hotter design condition. The supplier and project engineer should agree which evidence applies and whether further testing is required. Use the BESS FAT and SAT guide to define responsibilities and acceptance records.

Send the site conditions with your technical request

Include the location, altitude, available weather and interval load records, intended operating mode, required power and duration, and any proposed PCS or site layout. Use the model-specific document links above if a product is already being evaluated. If selection is still open, send a project enquiry and ask HUA-X to identify the supported configuration, evidence available and remaining engineering questions. The BESS RFQ checklist provides the wider project information to include.