A factory already has solar PV. Its owner wants lower electricity bills and backup for some critical equipment. The installer has monthly bills, the PV capacity and an equipment list, but no agreed backup duration, load profile or battery size.
That is enough to start preparing the BESS project requirements. The useful first deliverable is a brief showing what the site needs, what the available evidence supports and which questions need answers next.
This guide follows that factory through the process. Copy or download the template below into your own document and fill it as you read. You will finish with a working requirements brief and an action list for the next discussion, not a completed design or approved installation.
Start your project brief with what you already know
Keep the overview short, with bills, drawings and data files attached separately. Give each attachment a clear reference so someone receiving the brief can find the evidence behind an entry.
Copy-and-fill project overview
Project / site: ______
Prepared by / contact: ______
Date / revision: ______
| Field group | Record in your brief | Your entry and evidence reference |
|---|---|---|
| Project and goals | Location; existing or planned site; problem to solve; main and secondary goals; priority | ______ |
| Consumption and generation | Available bills and data; meter location; working shifts; PV information; expected changes | ______ |
| Backup | Equipment or circuits to support; duration; allowable interruption; load shedding and restart needs | ______ |
| Grid and recharge | Connection details; import/export limits; proposed charging sources and windows; restrictions | ______ |
| Existing equipment | PV inverters; generator, if present; switchgear; metering; controls; available drawings and interface documents | ______ |
| Site | Candidate location; dimensions and photos; access; environment; known installation constraints | ______ |
| Power and energy | Target kW and kWh, if supported; otherwise “to be analysed”; source and meaning of any proposed figures | ______ |
| Scope and programme | Supply and integration responsibilities; local assessment contacts; timing; budget status; expansion plans | ______ |
Use Confirmed only where an entry has a stated basis and a person who checked it, and note the confirmation date. Use Estimated with its assumptions, Unknown where evidence is missing, and Not applicable with a reason. A document that has arrived but has not been checked is Received / unverified.
For the hypothetical factory, the starting attachment list contains the monthly bills, PV capacity information and equipment list. Having these files does not mean they describe the right circuits, operating periods or current configuration. The power and energy entries remain to be analysed.
If someone has already suggested a battery size, note who suggested it and why. A budget allowance, an equipment quotation and an engineering calculation are different bases for the same-looking number.
Define the service your site needs
Start with the operating problem. The choice of battery follows the service you ask it to perform.
Make the cost objective specific
Look at the bill and ask which charge the owner wants to reduce. Is the concern total imported energy, expensive time periods or a demand charge? If nobody has checked, write bill review needed and assign that task.
Do not translate lower bills straight into peak shaving. Nor does an existing PV array prove that there is surplus solar energy available for storage. Those are possibilities to investigate against the site's tariff and operating data. REopt's introduction to energy-system analysis takes the same approach: utility rates and site consumption are the inputs, and sizing and operating schedules follow from them.
Describe what must remain powered
For backup, ask the owner and facilities team to identify:
- The equipment or circuits that need power during an outage.
- How long each must operate, and whether any can be disconnected.
- The interruption each process can tolerate.
- Whether equipment must keep running or can stop and restart, including any restart sequence.
The answers need to describe the process. Equipment nameplates won't tell you which machines run together or what happens when they restart.
Illustrative example (hypothetical factory)
| Starting request | More useful entry in the brief |
|---|---|
| Lower electricity bills | Identify which bill components storage could address. Billing mechanism and operating strategy remain unconfirmed; request the tariff details. |
| Back up important equipment | Support a selected group of critical loads. Facilities and operations must confirm the list, duration, allowable interruption and restart needs. |
The owner also needs to decide how these goals interact. If stored energy is used for everyday savings, what backup availability must still be maintained? Write down the required service priority before anyone chooses a reserve setting. For our factory, that priority is still open. It is worth settling early.
Update the Project and goals and Backup rows now. A clearly described unanswered question is more useful than an assumed requirement that later changes the design.
Match each goal to the evidence you need
Collect evidence for the service under discussion. You do not need every possible dataset before an initial conversation.
| Question to analyse | What the current material helps establish | What to obtain next, and from whom |
|---|---|---|
| Which electricity costs could storage address? | Bills show the consumption and charges actually listed | Current tariff and billing rules from the account holder or electricity supplier |
| When does costly grid demand occur? | Bills may show billed demand, but not the full event | Time-stamped import/load data from the metering provider or facilities team |
| Is solar available for charging? | PV capacity identifies the installation's stated scale | Generation and site consumption/import-export records covering matching periods, from PV monitoring and site metering |
| What must run during an outage? | Equipment list identifies candidates | Critical-load selection, operating schedule, interruption tolerance and starting information from operations and the electrical team |
Monthly totals cannot show the shape of every peak, or how factory operating hours line up with solar output. NLR's REopt guidance on load data separates measured interval data from simulated profiles scaled from monthly bills. Both can support analysis, as long as a simulated profile stays labelled as an estimate.
Label the data before using it
For each time-series file, note its measurement point, units, dates, time interval, time zone and known gaps. Say which shifts or production conditions it represents, including shutdowns, unusual activity or planned expansion.
At a solar-equipped site, identify whether a file represents whole-site consumption, grid import after solar contribution, PV generation or a particular circuit. Ask the engineer to work out how the files relate before combining them, or the same solar contribution could be counted twice.
The required detail depends on the question. A billing analysis and a motor-starting assessment need different evidence. Ask the person doing the analysis whether the available records capture the event in question. No fixed sampling interval or number of months works as a universal acceptance rule.
For the hypothetical factory, two immediate actions are to ask the account holder about meter-data access and ask operations to mark the critical equipment on the existing list. The PV monitoring contact should also check what generation records can be exported.
If records are unavailable, note whether the next step is an authorised data export, a measurement plan from the electrical team or a documented estimate for preliminary comparison. State which conclusion remains dependent on better evidence.
Record the connection, equipment and site constraints
The load and tariff describe the intended duty. The existing installation determines what else needs checking before a configuration can be selected.
Connection and recharge
Ask for the available single-line diagram—the drawing showing the main electrical connections—and the connection agreement or other evidence of import and export limits. Note the supply voltage and frequency from the site documents.
For recharge, ask three things: where the energy will come from, in what time window, and what other loads are running then. A transformer's rating doesn't tell you how much charging capacity is spare. A low-price period tells you when power costs less, not how much energy the site can actually put back into the battery.
Keep grid-available and outage conditions separate. If the plan relies on PV during an outage, request confirmation of that operating capability. The U.S. Department of Energy's Solar and Resilience Basics explains why you shouldn't assume ordinary grid-dependent solar keeps running through an outage. For this factory, the proposed system's inverter, switching and control arrangements need their own assessment, and the brief should name that question and the engineering party responsible for it rather than prescribe a wiring arrangement.
Existing equipment and control responsibilities
List the PV inverter models and any generators, existing storage, switchgear, meters or control systems. Include available manuals, firmware information and interface documents. Note who can provide authorised access to settings and operating data.
The power conversion system (PCS) and energy management system (EMS) become important here: the integration team needs to know what equipment will exchange power and who will coordinate its operation. Seeing RS485 or CAN listed as an interface is only the start. Whether the required commands, data and operating behaviour are supported still needs an answer. Ask the manufacturers and integrator to confirm the intended interface.
If the project later reaches cabinet selection, our all-in-one versus battery-only comparison explains the equipment and responsibility split. It covers new grid-connected installations with no mandatory existing PCS to reuse. Retrofit compatibility and backup functions still need separate checks.
Site, scope and programme
Collect photos and dimensions of the candidate location, its relationship to the electrical connection point, delivery access and maintenance access. Note known environmental, drainage, foundation or noise concerns. Name the local professional or authority who needs to confirm the applicable siting, fire and connection conditions.
Leave the suitability decision with the people assessing the complete installation, even when a cabinet fits the outline neatly.
Finally, write down who is expected to supply equipment, integrate it on site and coordinate local assessments. Note the desired completion date, what milestone it refers to, the budget status and any expansion plan. Where these remain undecided, assign the project coordinator (the person who maintains the brief and chases its open items) to obtain an owner decision or identify the appropriate contractor.
Give every important unknown a next action
Keep important open items in a short action log. Each should explain what it affects, where an answer might come from and when that answer becomes necessary.
Copy-and-fill open-items log
| Open question | Decision affected | Next action / evidence source | Responsible person | Resolve before |
|---|---|---|---|---|
| ______ | ______ | ______ | ______ | ______ |
Add rows as needed and reference them from the overview. Number the rows so the overview can point to them; the example below uses U1, U2 and so on (U for unknown). Missing data, an undecided business priority and an unverified equipment interface need different people. If the responsible person is unknown, assign the coordinator the task of finding them.
Illustrative example (hypothetical factory)
| Open question | Decision affected | Next action / evidence source | Proposed responsible role | Resolve before |
|---|---|---|---|---|
| U1: Which charges and demand periods should be targeted? | Savings strategy | Review bills and tariff; request time-stamped meter data | Account holder with EPC analyst | Choose the cost-reduction duty |
| U2: Which loads need backup, for how long and with what interruption tolerance? | Backup duty and conversion requirements | Mark equipment list; obtain operating and restart requirements | Operations with electrical team | Confirm backup sizing and functionality |
| U3: What charging energy and connection headroom are available? | Recharge feasibility | Obtain aligned PV/load records and documented connection limits; review proposed charging windows | Facilities, PV contact and electrical engineer | Confirm recovery and repeat operation |
| U4: What priority must backup retain during daily operation? | Energy allocation | Agree required backup availability and permitted trade-offs | Site owner with operations | Agree the operating policy |
| U5: What existing equipment can participate, especially during outages? | System architecture | Collect diagrams, models and interface documents; request compatibility assessment | Integrator with relevant manufacturers | Confirm a configuration |
| U6: What site and delivery conditions apply? | Layout, local requirements and project scope | Confirm location; collect photos/dimensions; identify local assessors; agree responsibilities, timing and budget status | Project coordinator with owner and local specialists | Commit to affected layout, scope or schedule decisions |
U4 matters because normal operation changes how much stored energy remains when an outage begins. SAM's Grid Outage documentation makes the same point from the modelling side: critical loads, outage conditions and battery state of charge are all explicit inputs. The owner defines the required service; the engineering team assesses how to provide it.
An open item does not stop every activity. U5 may prevent a firm compatibility claim while U1's billing analysis proceeds.
The factory's brief at this point
Illustrative example (hypothetical factory)
- Context: Operating factory with existing PV; detailed location and connection information still to be collected under U6 and U3.
- Requested services: Lower electricity costs and backup for selected critical loads; detailed duty and priority remain open under U1, U2 and U4.
- Available attachments: Monthly bills, PV capacity information and equipment list; received, not yet verified for the required analyses.
- Power / energy: To be analysed after the duty and inputs are established.
- Site / integration / programme: Open under U5–U6; no equipment format or delivery commitment selected.
- Next handover: Existing attachments plus U1–U6 for responsibility assignment and data collection.
Before sending your own brief, check that each important entry has a status and evidence reference, and that each important unknown has an action. Keep assumptions visible when you update the document.
Decide what your project is ready for next
Use the information available to choose the next task. These are working distinctions, not approval gates; analysis and configuration checks often run in parallel or send questions back to the owner.
| Current information | Work that can begin | What remains unconfirmed | Next handover |
|---|---|---|---|
| Site and problem described; available records and gaps listed | Initial requirements discussion and data-collection planning | Final capacity, savings and equipment suitability | Overview and open-items log to EPC, integrator or manufacturer |
| A defined service, with load, tariff or backup inputs and documented assumptions | Power/energy analysis for that service; preliminary comparisons where inputs are still estimated | Final sizing while key assumptions are unresolved | Data and limitations to the responsible analyst; ask for missing measurements or owner decisions |
| Analysis range plus connection, backup, equipment and site conditions | Conditional configuration screening and interface discussions | Unverified compatibility, detailed design and local approvals | Requirements and open technical conditions to supplier, integrator and local engineer |
For our factory, the next step remains requirements clarification and data collection. The brief now lets you hand that work to specific people. It still cannot establish a battery capacity, a model or proven backup performance.
When a backup duty is sufficiently defined, the two-hour commercial backup sizing example shows how to work through power, energy and recharge. Its assumptions belong to that example; they are not default inputs for your factory's savings or solar-storage analysis.
Once the site constraints and system needs are clearer, compare cabinet and container formats. Use the C&I BESS supplier guide when evaluating how suppliers back up their responses to your requirements.
What if your site doesn't match the example?
Use the design equipment schedule, expected operating hours and documented load estimates supplied by the project team. State their source and mark them Estimated. Ask the analyst which uncertainties need scenario comparisons and what should be verified once operating records exist. The overview and action log still work. Just don't present a forecast as measured site performance.
Write down the restriction, its source and the connection point it applies to. Ask the local electrical engineer and integrator to assess the required controls and connection conditions. That restriction alone doesn't settle whether the proposed storage project is feasible or compliant.
To discuss your project with GeePower, send a short requirements summary or email your brief and available attachments to info@geepoweress.com. Include your location, main goal, current project stage and open questions. Power and energy figures can remain to be analysed. Involve your local EPC or electrical partner in the site and integration questions. A partly filled brief is a perfectly good starting point.
Download
👉 GeePower BESS Project Requirements Workbook
References / Sources
- National Laboratory of the Rockies — What Is REopt?. Utility rates, site consumption and system-analysis inputs.
- National Laboratory of the Rockies — Interpreting Utility Bills—Load Data. Monthly billing information, estimated profiles and measured interval data.
- U.S. Department of Energy — Solar and Resilience Basics. Grid-dependent PV operation and the need for appropriately configured outage operation.
- System Advisor Model (SAM) Help — Grid Outage. Critical-load, outage and battery-state modelling inputs; not a site design standard.