State Tenders Now Mandate Storage Alongside Solar: What Co-Located BESS Does to the Underwriting File

Bihar State Power Generation Company Limited (BSPGCL) invited bids for 150 MW of solar PV paired with 75 MW/300 MWh of battery energy storage, with bid submission closing on 21 August 2026. The tender's structural detail matters more than its size: bidders must provide at least 0.5 MW/2 MWh of BESS for every 1 MW of project capacity. The battery is not an optional sweetener. A bidder cannot win the solar without building the storage, and the two assets will share a site, a grid connection and a power purchase agreement.

BSPGCL is not an outlier. India issued 44.1 GW of renewable energy tenders in the first half of 2026, with 16.3 GW successfully auctioned, and a growing share of state and central tenders now specify firm and dispatchable supply, which in practice means solar or wind wrapped around storage. The economics that made this possible are recent: BESS tariffs discovered in competitive tenders fell 86%, from Rs 10.83 lakh/MW/month in a 2022 pilot tender to a record low of Rs 1.48 lakh/MW/month in December 2025. At that price, procurers can mandate storage without wrecking the levelised tariff, so they do.

For brokers and underwriters the consequence is simple. The standalone ground-mount solar submission, a risk the Indian market has priced for a decade, is being replaced by a hybrid submission in which a lithium-ion battery block sits inside the solar plant's fence. That changes the fire risk, the business interruption chain and the construction-phase cover, and each change needs to be handled in the wording rather than absorbed silently into last year's rating.

A ground-mount solar plant is a low fire load risk. The combustible inventory is cable insulation, module backsheets and inverter electronics, spread across hundreds of acres, and the historical loss record is dominated by weather, theft and electrical breakdown rather than spreading fire. A lithium-ion BESS block breaks that profile.

Thermal runaway is the failure mode that defines the class. A single cell fault, whether from an internal manufacturing defect, overcharge, physical damage or external heating, drives the cell into a self-sustaining exothermic reaction. Heat propagates to neighbouring cells, the module vents flammable electrolyte gases, and the event can escalate from one cell to a full container. Three characteristics matter to a property underwriter:

• Reignition. BESS fires can reignite hours or days after apparent extinguishment, because stranded energy remains in damaged cells. The loss is not over when the flames are out.
• Suppression limits. Water cools but does not reliably stop cell-to-cell propagation inside a sealed container, and many rural solar sites have no firewater infrastructure at all. The practical strategy for a container in full runaway is often controlled burn-down with exposure protection, which concedes the container as a total loss.
• Gas and deflagration risk. Vented electrolyte gases are flammable and can deflagrate inside an enclosure, which is why deflagration venting and off-gas detection appear on underwriter question sets.

We covered the cell-level engineering of this exposure in [our BESS underwriting note](/underwriting-risk/ev-battery-storage-bess-underwriting-india-2026). The co-location twist is that the battery no longer sits on its own industrial plot. It sits next to inverter stations, the pooling substation and the control room of a revenue-producing solar plant, so the question is not only whether the container survives but what its loss does to everything around it.

In the absence of a dedicated Indian fire code for grid-scale storage, underwriters lean on international references, chiefly NFPA 855 for siting and separation and UL 9540A large-scale fire test data for the specific cell, module and unit combination being installed. Expect the property and engineering markets to ask for, and price against, the following:

1. Container-to-container spacing. Enough clear distance between BESS enclosures that a full container burn-down does not propagate to the next unit, with the layout drawing showing actual distances rather than an assurance.
2. Separation from the balance of plant. Distance from the BESS yard to inverter stations, the pooling substation, transformers, the control building and the nearest module rows. The substation is the item to defend hardest, because losing it idles the entire plant.
3. Fire brigade access and water. All-weather access roads to the BESS yard, hydrant coverage or a static water tank sized for exposure protection, and a realistic statement of the distance and response time of the nearest fire station. For remote sites in Bihar, Rajasthan or Karnataka that answer is often sobering, and the layout must compensate for it.
4. Detection and shutdown. Off-gas detection that trips the affected rack before runaway spreads, battery management system (BMS) alarms routed to a manned point, and remote isolation of strings.
5. Cell chemistry and test evidence. Lithium iron phosphate (LFP) chemistry with UL 9540A test reports at unit level reads very differently from an undocumented pack, and underwriters increasingly decline to price without the test data.

A co-located project typically evacuates power through a single pooling substation and a single transmission connection, and it earns under a single PPA that assumes both assets perform. That coupling is where the business interruption estimate most often goes wrong.

If a BESS container fire damages or contaminates the adjacent substation, or forces a precautionary shutdown while the site is made safe and reinspected, the solar plant stops exporting even though not a single module is damaged. The business interruption sum insured therefore has to be built on full-plant outage scenarios, not on the battery's own revenue alone. The reverse also holds: storage-linked tenders pay for dispatchability, and a plant that can no longer time-shift energy may face PPA penalties or lose the storage tariff even while the solar half runs normally.

Three wording points follow:

• Interdependency within the site. The policy should state clearly that physical damage to one asset triggering revenue loss at the other, within the same insured project, is covered. Most standard wordings get there implicitly for a single insured location, but a hybrid project financed and metered as two blocks invites argument, so remove the ambiguity.
• Denial of access and precautionary shutdown. A runaway event can close the site to operations staff for days without damaging the solar field. Check whether the BI trigger requires physical damage to the equipment that stopped earning, and negotiate extensions where it does.
• Indemnity period against real lead times. Substation transformers and BESS replacement containers both carry long delivery times. A twelve-month indemnity period is optimistic for either; for a combined loss it is plainly short, and the same logic we set out for solar module lead times applies with more force here.

During construction, the project needs an erection all risks (EAR) policy with delay-in-start-up (DSU) cover, also written as advance loss of profits (ALOP). The hybrid structure complicates both, because the solar field and the battery yard sit on different commissioning clocks. Solar commissions in part-capacity blocks over months; the BESS arrives as factory-built containers on an import-dependent delivery schedule and commissions comparatively quickly once energised, but a shipping delay or a damaged consignment can push it past the solar COD by a quarter or more.

Structural points for the placement:

1. Insure the revenue streams separately in the DSU schedule. Under the tender structures now common, the energy revenue and the storage payment behave differently. The storage component is often a fixed monthly capacity payment (the December 2025 discovery of Rs 1.48 lakh/MW/month is exactly such a figure), so a month of delay converts to a known, contractually defined loss. Scheduling the two streams separately makes the loss calculation mechanical instead of contested.
2. Match the DSU trigger to the tender's commissioning definition. If the PPA recognises part-commissioning of solar capacity but pays the storage tariff only from full BESS availability, a delay confined to the battery still destroys the storage revenue in full. The DSU wording must respond to delay in each defined revenue stream, not only to delay of a single project-wide COD.
3. Marine and marine DSU. Battery containers, transformers and inverters arrive by sea. A single lost or damaged consignment of BESS containers is a classic marine delay-in-start-up scenario, and the marine DSU must dovetail with the EAR DSU so the delay is covered whichever policy the physical loss falls under.
4. Testing and the hot phase. The highest-hazard window is commissioning and grid charging of the battery, when cells first cycle at site. Confirm the EAR testing period covers it, that the insurer knows the testing schedule, and that handover to the operational policy does not leave a gap in the week the risk is at its peak.

The general architecture of DSU and ALOP for Indian projects, including how lenders read the cover, is set out in our DSU and ALOP guide; the hybrid tender simply forces the two-clock discipline onto it.

Every BESS supply contract carries a degradation warranty: the supplier guarantees the battery will retain a stated fraction of its energy capacity at defined points in its life, with an augmentation plan to top up capacity as cells fade. Buyers sometimes read this as quasi-insurance. It is not, and the gap between the two instruments is where uninsured loss accumulates.

The warranty answers for gradual, expected capacity fade under specified operating conditions. The insurance policy answers for fortuitous physical loss or damage. Between them sit at least three exposures that neither instrument cleanly owns:

• Accelerated degradation after an insured event. A fire or overheating event in one container can age surviving cells beyond the warranty curve. The insurer pays for the destroyed container; the supplier argues the survivors were operated outside warranty conditions during the event. The lost future capacity of the surviving racks falls between the documents.
• Serial defects. Most property and EAR wordings exclude the cost of rectifying a defect itself, and some exclude loss from an identical defect across identical items once the first failure is known. A cell-level manufacturing fault across a container fleet is precisely that scenario, and the practical recourse is the supplier warranty, which makes the supplier's balance sheet and the warranty's security (bank guarantee, parent guarantee, or nothing) an underwriting item in its own right.
• Mismatch on reinstatement. After a partial loss, replacement cells of the original age and specification will not exist. New cells in an old string create imbalance the BMS must manage, and the difference between old-for-old indemnity and the new equipment actually purchasable is a reinstatement value question the policy basis of settlement should answer before the loss, not after.

One more Indian regulatory layer bears directly on claims. The Ministry of New and Renewable Energy maintains the Approved List of Models and Manufacturers (ALMM): List-I for solar PV modules, updated on 3 August 2026, and List-II for solar PV cells, whose ninth revision was dated 21 August 2026, the same day the BSPGCL bid window closes. Projects procured under government tenders must use listed equipment, and that obligation does not lapse when the equipment is bought as a replacement after a loss. A reinstatement plan that assumed freely available imported modules can founder on ALMM compliance, stretching lead times and therefore the BI and DSU indemnity periods that must absorb them. Sums insured should be built on the delivered cost of compliant equipment, not on the cheapest global price.

The placement file for a co-located project should reach the engineering and property markets with, at minimum:

• Site layout drawing with measured separation distances between BESS containers, the substation, inverters and module rows.
• Cell chemistry, supplier, and UL 9540A test documentation for the installed configuration.
• Fire strategy: detection, off-gas monitoring, suppression philosophy, water source, access, and the local fire service response reality.
• The PPA's commissioning and payment mechanics, so DSU and BI can be scheduled against the actual revenue streams.
• The degradation warranty, its security, and the augmentation plan.
• Commissioning programme showing both clocks, the testing window and the intended EAR-to-operational handover date.

Tenders like BSPGCL's make one thing certain: within a procurement cycle, most new Indian solar submissions will carry a battery. Brokers who restructure the file now, rather than renewing standalone-solar wordings onto hybrid assets, will be the ones whose clients get paid without argument when the first container lets go.