Is My Factory Suitable for Solar and Battery Storage? A Five-Point Check You Can Run Yourself
Your factory is a serious candidate for solar and battery storage when five things are true at the same time: your load runs while the sun is up, your maximum demand is spiky relative to your contract demand, your diesel generator runs more hours than anyone will admit, your process is damaged by short grid dips, and you have shade-free roof or ground that a cable can reach. Three or more yes answers and a paid feasibility study is money well spent. One yes and it is not.
Most plant heads get this backwards. They begin with a quotation for a 1 MW plant, then try to work out whether it fits. The useful order is the opposite: establish whether your plant has the five characteristics that make solar and storage pay, and only then let anyone size anything. The check below takes ten minutes with last year's bills, the DG logbook and a site plan.
The five-point check in one table
Fill this in before you read any further. Use twelve months of bills, not one.
| # | Signal | What counts as a yes | Where the data lives | Your answer (Y/N) |
|---|---|---|---|---|
| 1 | Daytime load | Substantial, steady load between roughly 09:00 and 17:00 on most working days | 15-minute load data from the HT meter, or an energy audit | |
| 2 | Demand headroom | Recorded demand regularly approaches contract demand, or demand charges are a large share of the bill | Maximum demand line on twelve monthly bills | |
| 3 | Diesel hours | DG runs more than a few hundred hours a year, or you pay for standby you never use | DG logbook, fuel register, running-hour meter | |
| 4 | Trip sensitivity | A two-second dip costs a batch, a melt, a reactor charge or a half-shift of restart | Shift incident log, rejection records | |
| 5 | Usable area | Shade-free roof or ground that can carry the load, with a cable route to the panel room | Site plan, roof structural drawing |
Your score is the count of yes answers out of five. Nothing more sophisticated than that is needed at this stage.
Signal 1: does your load run when the sun does?
Solar generates in a bell curve centred on midday. A single general shift is close to ideal. Three shifts with a flat load is also good, because the daytime block still absorbs everything a roof plant produces. The case that fails is the plant running mainly nights, or whose daytime load is small because the heavy process runs after 22:00 to catch a cheaper energy slot.
Self-consumption is the whole economic case for industrial solar. A unit you generate and consume behind your own meter displaces a unit you would have bought at your full tariff. A unit you export is settled at whatever the order in force allows, which is a different and usually much smaller number. Before you size anything, work out what fraction of generated units your own load will swallow.
Pull the 15-minute interval data from your HT meter — most utilities will provide it. Overlay a generic solar curve on your weekday profile and on your Sunday profile. The gap on Sunday is the first honest picture of surplus most plants ever see.
Signal 2: how far apart are your contract demand and your recorded demand?
Two different failures show up here, and both point towards storage rather than away from it.
The first is the plant that bumps its demand month after month because of a handful of fifteen-minute blocks — a compressor and a chiller and a mill starting together, a furnace charging, a shift changeover. The average load is modest. The billed demand is not.
The second is the plant that has already raised contract demand to cover those spikes and now pays for headroom it uses a few hours a month. If you do not know which you are, read our guide to how maximum demand charge is calculated and why it ratchets with a bill in front of you.
In our experience building and retrofitting PCC and MCC boards, the demand figure on the bill is almost never matched by any instrument inside the plant. Plants measure current at the incomer and feel they know their demand. They do not. Our recommendation: before a single module is quoted, meter the incomer and the three or four largest feeders, log for a month, and look at fifteen-minute blocks rather than the panel ammeter. We have had clients discover their peak was being set by a standby pump that auto-started alongside the main one.
Signal 3: how many hours does your DG really run?
Ask the plant head and you get one number. Read the running-hour meter and the fuel register and you get another, larger one. Diesel generation is the most expensive electricity in the plant by a wide margin, and the cost per unit worsens sharply at low load factor because specific fuel consumption rises as loading falls.
High DG hours are a strong signal for storage, because a battery with the right control can hold the plant through the outages that currently start the DG. Low DG hours are not a disqualification; they simply move the arithmetic onto demand charges and self-consumption. Work your own figure out using the method in what a diesel generator costs per unit.
Specific fuel consumption is the litres of diesel burned per kWh produced, and it is the single number that decides DG economics. It is commonly quoted around 0.25 to 0.30 litres per kWh near full load for a modern set, and it degrades badly below about 40 per cent loading.
Signal 4: what does a two-second dip cost you?
This is the signal that most often changes the answer from maybe to yes, and it is the one nobody has quantified.
A grid dip of a few cycles will not trip your lighting. It will drop out contactors, stall VFDs on undervoltage, and bring a continuous process down. In a pharma plant a lost batch is lost; in a plastics plant a solidified screw is a day's work; in a foundry a dropped melt is scrap plus refractory damage. If you have never put a number against this, the exercise in what one power trip costs a process plant is worth an hour of your time.
A battery sitting behind the meter, with a power conversion system that can pick the load up fast enough, changes this. A DG set cannot — it has to be told to start, come up to speed, then be synchronised and loaded, and by then the process has already fallen over. This is why plants with a perfectly functioning automatic mains failure scheme still lose batches: the sequence works, and arrives too late.
Signal 5: do you have the area you think you have?
This is where optimistic feasibility reports fail. Gross roof area is not usable area. Subtract the sheds you cannot load structurally, the skylights, monitor roofs, exhaust cowls, duct runs, firewater lines, the area shaded by a chimney or cooling tower for part of the day, cleaning walkways, and inter-row spacing on a flat roof.
| Area question | Why it reduces usable area |
|---|---|
| Is the structure assessed for added dead load and wind uplift? | Older trussed sheds commonly need strengthening first |
| How old is the sheeting? | Nobody should mount a 25-year asset on sheeting with five years left |
| What shades the roof, and at what hour? | Chimneys, tanks and taller sheds steal morning or evening generation |
| Where is the LT or HT room relative to the array? | Cable runs, tray routing and entry into a full panel room cost money and space |
| Is the area needed for expansion? | An array over your only expansion bay is a decision, not a detail |
Usable roof area is commonly well below the gross figure once all of this is deducted, and ground-mount needs considerably more area per MW than roof because of row spacing. Measure the usable area on a drawing rather than dividing your shed footprint by a number someone gave you on the phone.
How to read your score
| Score | What it means | Sensible next step |
|---|---|---|
| 5 / 5 | Strong candidate for solar with storage | Commission a study with 15-minute data; ask for self-consumption, not just generation |
| 4 / 5 | Strong candidate, one constraint first | Identify the failed signal and whether it is fixable |
| 3 / 5 | Worth studying, probably in phases | Solar first, storage later, with the electrical side built to accept it |
| 2 / 5 | Weak case today | Fix metering and power factor; revisit when load or tariff structure changes |
| 0-1 / 5 | Not a candidate | Spend on demand management, motor efficiency and harmonics instead |
When the answer is no, and why that is worth knowing
Some plants should not do this, at least not yet. A single-shift unit with a modest daytime load, a reliable supply, no DG hours and a roof with four years of life left in it is not a solar candidate, and no amount of enthusiasm changes that.
We push back when a client scoring one asks us to quote the electrical balance of plant anyway. It costs us an order, but a plant that installs on a weak case spends the next decade explaining the decision. The useful work for that client is upstream: metering, power factor correction, harmonic treatment on the VFD-heavy feeders, and a hard look at why the demand peaks where it does.
A no today often expires. Tariff structures change, shift patterns change, and a new line changes a daytime profile completely. Re-run the five points whenever something structural changes in the plant.
What this check deliberately does not tell you
It does not tell you system size, cost, payback or internal rate of return. It cannot, because those depend on your tariff category, your consumption pattern, the banking and settlement rules in force at the time, and the capital you can deploy. Anyone producing a payback figure from your shed area and a satellite image is producing a sales document, not an engineering one. What the check does tell you is whether the study is worth commissioning, which is a different and much cheaper question.
The electrical questions that decide feasibility more than the solar does
Here is the part that gets skipped. A solar or storage addition is an electrical integration into a plant that already has a system, and the existing system is usually the constraint.
Where does the inverter output land? If the answer is "the main PCC", somebody has to find a spare outgoing section with the right fault rating, or add one. Is the board's short-circuit withstand still adequate once a second source is connected? Is the busbar rated for the additional current? Is the panel old enough that the right answer is a retrofit rather than bolting new equipment onto tired switchgear?
In our FAT experience across LT boards built in our Vadodara works, the three issues that delay a solar connection are always the same: no spare outgoing way, a busbar system that cannot take the extra current without a rating study, and earthing arrangements that were never documented and now have to be established before a second source can be connected safely. None of these are solar problems. All of them land on the solar project's schedule.
For storage the questions widen. The DC side needs properly designed string protection and isolation, which is what a solar ACDB and DCDB is for. The AC side needs a point of connection with protection that coordinates with everything upstream and downstream. If you already have a DG set and a synchronising scheme, the interaction between the battery, the DG and the grid becomes a control problem before it becomes a hardware problem.
What to collect before you talk to anyone
Walk into the first meeting with this and you will get a serious answer instead of a brochure.
| Document | Why it is needed |
|---|---|
| Twelve months of bills | Demand pattern, billing demand, power factor history, seasonal variation |
| 15-minute interval data for one month | Self-consumption and peak shaving potential — the most valuable file |
| As-built single line diagram | Where a new source can actually be connected |
| DG logbook and fuel register | Real running hours and real load factor |
| Roof structural drawing or assessment | Whether the roof can carry an array at all |
| Shutdown calendar and shift pattern | When surplus will arise |
| Panel schedule with ratings | Spare ways, busbar rating, fault level |
Across the 17 industrial projects we have delivered across India, one lesson repeats, and it is not about equipment. It is that electrical documentation inside an operating plant is almost always out of date, and the first week of any serious study goes on establishing what is actually installed. Our recommendation: fix the single line diagram before you commission the study, not during it.
A word on standards, and on claims
Low voltage assemblies are built and verified to IEC 61439, which covers low voltage assemblies only. Medium voltage switchgear is governed by a different standard — IEC 62271-200, and IS 3427 in Indian practice — so a low voltage standard cited against an 11 kV panel tells you something about the supplier's depth. On the storage side the relevant families are IEC 62619 and IEC 62933, UL 9540A for the thermal runaway test data your insurer will ask for, IS 16270 in Indian practice, UN 38.3 for transport, and NFPA 855 for installation separation and fire strategy. Grid connection sits under the CEA regulations and your state commission's procedure.
This is the common mistake we see at proposal stage: a vendor presents a certificate for a cell and lets the reader assume it covers the system. Ask which document applies to the cell, which to the rack, which to the complete system and which to the installation. They are four different things.
The governing principle
Solar and storage do not save a factory money because they generate electricity. They save money because they displace expensive electricity at the moment the plant is consuming it, and because they remove costs — demand charges, diesel hours, lost batches — that have nothing to do with units at all. Every point in the five-point check is a proxy for that one question.
Run the check honestly. Score three or more and commission a real study with real interval data. Score one and you have saved yourself a year of meetings.
Frequently Asked Questions
What is the single most important factor in deciding if a factory suits solar?
Daytime self-consumption. A unit generated and consumed behind your own meter displaces a unit at your full purchase rate, while a unit exported is settled under whatever rule is in force and is usually worth considerably less. A plant with a strong, steady daytime load extracts far more value from the same array than a plant that runs mainly at night.
How much roof area does an industrial solar plant need?
Far more than the gross roof figure suggests, because skylights, cowls, walkways, shaded zones, structurally unsuitable bays and cleaning access all have to be deducted. Ground-mount needs substantially more area per MW than roof-mount because of inter-row spacing to avoid self-shading. Measure the usable area on a site plan rather than estimating from the shed footprint.
Is battery storage worth it if my grid supply is reliable?
Possibly, but for a different reason. With a reliable supply the case shifts from backup to demand management — shaving the fifteen-minute peaks that set your billing demand and shifting solar surplus into evening load. If your demand charges are a small share of your bill and you have no surplus, the case is weak.
Can I add solar to my existing LT panel?
Only if the board has a spare outgoing way of adequate rating, a busbar system that can carry the additional current, an appropriate fault level, and documented earthing. Many operating plants fail at least one of these. The check should be done by someone who will put their name to a rating assessment, not assumed from the panel drawing.
How many DG running hours justify looking at battery storage?
There is no universal threshold, because it depends on your load during those hours and on what each outage costs you beyond fuel. As a working rule, a few hundred hours a year with significant process at risk is enough to make the comparison worth doing properly. Build your own cost per unit before comparing — the fuel invoice alone understates it.
What is contract demand and how is it different from maximum demand?
Contract demand is the capacity you have contracted with the utility to draw, while maximum demand is the highest average load your meter actually recorded in the billing period. You are billed on a billing demand derived from both, subject to the ratchet clause in the tariff order in force. The three numbers are regularly confused, and the confusion is expensive.
Should I do solar first and storage later?
Often yes, provided the electrical infrastructure is designed from day one to accept storage without being rebuilt. That means leaving a suitably rated spare way, planning the cable route, sizing the earthing and specifying metering and control that storage can later use. Retrofitting storage into a board that was built with no allowance for it is the expensive path.
Will solar reduce my maximum demand charge?
Not reliably on its own. Solar reduces imported units during daylight, but your billing demand is set by the highest recorded block, which may fall on a cloudy afternoon, an evening shift or a monsoon day. Reducing demand charges dependably requires either load management or storage with a control scheme that targets the demand peak.
What should a feasibility study contain that a vendor proposal does not?
Interval load data analysed against a modelled generation profile, a self-consumption percentage, a monthly surplus estimate including weekends and shutdowns, a connection study against the as-built single line diagram, and a statement of what is not known. A proposal opening with a payback figure and a shed area has skipped all of it.
Does a battery remove the need for a diesel generator?
Rarely in full, and it should not be assumed. A battery responds far faster than a DG set and can ride through the short dips that damage a process, but sustained outages need either a very large battery or a generator. Most industrial schemes end up with both, and the design question becomes how the battery, the DG and the grid are controlled together.
Which standards apply to a battery energy storage installation in India?
IEC 62619 and IEC 62933 cover cells and the storage system, UL 9540A provides the thermal runaway test data insurers and authorities commonly request, IS 16270 applies in Indian practice, UN 38.3 governs transport, and NFPA 855 is widely referenced for installation separation and fire strategy. Grid connection is governed by the CEA regulations and the procedure of your state commission. Ask the supplier which document covers the cell, the rack, the system and the installation — they are four separate things.
What is the fastest way to know if this is worth pursuing?
Score the five signals in the table above using twelve months of bills, the DG logbook and a site plan. Three or more yes answers justify a paid study with interval data; one justifies spending the money on metering and demand management instead. The check takes about ten minutes and is far more honest than a free assessment built from a satellite image.
Related Guides
- Load list and transformer/incomer sizing
- APFC panel sizing and kVAr calculation
- AMF vs ATS vs DG synchronization
- Maximum demand charge calculation
- Solar and BESS payback and IRR
- Roof and land area required for 1 MW of solar
- Product page: Solar ACDB and DCDB
- Service: Battery storage (BESS) EPC
- Service: Hybrid solar + BESS
Talk to Us About Your Plant
Wisdom Techno Solutions manufactures the electrical system that sits at the centre of a solar and storage installation — the LT panel, the switchgear, the metering, the protection and the control — at our works in Vadodara, Gujarat. We build solar ACDB and DCDB, and the same engineers who design an assembly test it before it ships and commission it on site.
Wisdom Techno Solutions is a licensed partner for three design-verified switchgear platforms: Rittal Ri4Power (Rittal Solutions Partner since 2021 — the Ri4Power system carries Intertek ASTA design verification to IEC 61439-1 and -2 Edition 3, with copper and aluminium busbar systems up to 6300 A), C&S CX (Licensed Partner since 2023, up to Form 4B Type II) and Siemens SIEPAN Elite/8PU (IEC 61439 Solutions Partner since 2024). We build to each system's verified configuration and routine-verify every assembly in-house at our Vadodara, Gujarat facility, for industrial, EPC and infrastructure projects across India. For a solar or storage plant that covers the LT switchboard, the BESS PCC and the AC and DC distribution.
If you want to know whether your plant is a candidate, send us twelve months of electricity bills and one day's load profile. That is enough to size a system, show where the savings would come from, and tell you honestly if the answer is no.
The quickest route is our free feasibility study: send the bills and we come back with the sizing and the numbers behind it. To work out your own numbers first, use the free electricity bill analyser.
Send your single line diagram, your load list or your last twelve bills, and we will come back with the electrical scheme and the numbers behind it.
The electrical system that ties solar, storage, the grid and the diesel set together is built and tested at our LT panel manufacturer in Vadodara.