1. What problem is the system meant to solve?
A BESS can serve several objectives: raising solar self-consumption, backing up critical loads, shaving peak demand, or supporting stable operation. Each objective leads to a different choice of battery capacity, inverter rating and control strategy.
Before asking for a price, rank your operational objectives. That ranking is the input that keeps the proposed configuration from being larger or smaller than what the site actually needs.
2. Is the load data detailed enough?
An electricity bill gives the broad picture but does not always show when peaks occur or how high they reach. Hourly data — or a shorter measurement interval — lets the engineering team understand base load, variable load and how long backup is required.
If suitable data does not exist yet, the survey stage should define how to measure it before the configuration is fixed. A performance estimate is only trustworthy when its data source and assumptions are written down.
3. Is the existing equipment compatible?
Existing solar arrays, inverters, switchboards and monitoring devices all impose integration constraints. Capacity, wiring diagrams, communication protocols and protection conditions need to be checked rather than assumed to connect directly.
An early technical survey separates what can be reused from what has to change, which is what makes the scope and the deployment risk concrete.
4. Are the safety, warranty and operating requirements clear?
Installation location, ventilation, electrical protection, fault-isolation strategy and operator access all belong in the design. The proposal should also state which equipment carries a manufacturer warranty and which services the integrator is responsible for.
After acceptance testing, the operator needs to know how to monitor alarms, reach support and handle situations outside normal operating conditions.
5. Which metric will verify the outcome?
Objectives should map onto data you can track — energy self-consumption, peak demand, or how long critical loads stay supported. The calculation method, the measurement period and the assumptions must be agreed before any result is compared.
There is no single payback period that applies to every project. The analysis has to reflect the tariff, the load profile, existing generation, the capital cost and the operating strategy of that specific site.