This logistics hub is illustrative. It is a representative facility, not a Ray2Volt installation. The figures demonstrate a way to calculate system size, bill effects and payback, and the photographs illustrate the sector.
Your roof, power profile and tariff will change the result. Ask for an estimate using your site data.
What the worked case shows
- A logistics shed may have far more roof area than its office and lighting load needs. Measure the whole site's daytime demand before sizing panels.
- Electric reach trucks, forklifts and last-mile delivery vehicles add charging demand that can be scheduled into sunny hours.
- The modelled 250 kWp Tier-1 DCR array generates about 3,62,000 units a year and cuts the HT bill by over ₹31.8 Lakhs. Standing-seam clamps avoid roof penetrations.
- The table calculates 3.28 years of cash payback and 2.95 years with its tax assumption. Typical business planning remains 3 to 5 years, subject to a site audit.
Warehouses in the Sri City Special Economic Zone (SEZ), Renigunta and the Chennai logistics belt now do more than store goods. E-commerce fulfilment, electronics distribution and automotive supply chains need sorting, handling and dispatch throughout the day. Third-party logistics (3PL) sites often run powered equipment alongside ordinary storage.
An older godown may only need lights and fans. A fulfilment centre can run high-bay LEDs, conveyors, pallet wrappers, temperature-controlled pharmaceutical zones and chargers for reach trucks, forklifts and electric three-wheelers. For this model, the APSPDCL Category II(A) Commercial HT or LT effective cost is ₹8.80 to ₹10.20 per unit, based on the APERC order dated 25 March 2026. Confirm the applicable category and current tariff on your bill.
A pre-engineered building (PEB) can offer a wide, gently sloping metal roof. That area is useful only if its structure and the site's daytime load support the proposed capacity. We use an 80,000 sq ft Andhra Pradesh hub to work through a 250 kWp system, roof clamps, fleet charging, monitoring and finances. See our warehouse solar services and factory solar guide for related designs.
Where warehouse electricity goes
Electricity used to be a small storage cost at many godowns. In this model, equipment and fleet charging make it a significant operating item. Break the demand into these groups:
- Electric material handling: Enclosed warehouses limit engine exhaust and soot, so 2.5-tonne electric counterbalanced forklifts and high-reach trucks may be used. Their 48V/80V industrial batteries draw power between shifts. Check ventilation and site rules for any combustion equipment.
- Delivery fleet charging: The example considers electric three-wheelers such as Mahindra Treo Zor and Piaggio Ape Electrik, plus small four-wheelers such as Tata Ace EV. Charging 25 to 40 delivery vehicles during afternoon sorting adds to peak demand.
- Conveyors and cross-dock sorters: Parcel sorters and motorised rollers run during daylight receiving and dispatch, creating a more predictable base load.
The representative hub operates from 7:00 AM to 6:00 PM. Conveyors and planned EV charging therefore overlap the solar production window. The scenario expects more than 92% direct self-consumption, while the financial table uses 94%. Interval demand and charging schedules should verify that assumption.
The illustrative fleet comparison uses ₹3.50 per km for diesel and less than ₹0.40 per km for energy from solar-powered EV charging. Vehicle efficiency, charging losses and the true solar cost will change those figures. Treat them as model inputs, not a fleet saving promise.
The representative Sri City logistics hub
The worked site is an illustrative distribution centre in the Sri City corridor. These are its stated inputs, not verified details of an actual installation:
- Building: An 80,000 sq ft PEB shed with 12-metre clear height, 16 loading docks and 5,000 sq ft of cooled administration space.
- Fleet: 8 electric reach trucks with 48V / 600Ah batteries, 12 electric pallet trucks and 20 regional delivery electric three-wheelers.
- Sanctioned demand: 300 kVA under APSPDCL HT Category II(A)(i) Commercial.
- Use before solar: 42,000 to 48,000 kWh each month, with a ₹4,25,000 average bill. The assumed blended ₹9.25 per unit includes demand charges and duty.
- Backup: One 250 kVA diesel generator using about 42 litres an hour during scheduled feeder shutdowns.
- Roof: 0.55mm standing-seam Zincalume sheets on an east-west dual pitch of 8 degrees.
Check the PEB roof before fixing panels
PEB frames are often designed closely around their intended loads. A large solar array adds weight and changes wind forces, so the roof drawings and condition need engineering review before installation. The example considers three checks:
1. Confirm the remaining load capacity
The illustrative PEB allows about 15 to 20 kg/m² of collateral dead load for items such as sprinkler pipes, high-bay lights and cable trays. Its 580 Wp modules, aluminium mini-rails and clamps add 11.5 to 13.0 kg/m². A finite element model (FEM) should check the existing Z-purlins and portal frames under full solar loading and confirm the assumed safety factor above 1.5. Do not infer spare capacity from roof area alone.
2. Clamp onto the standing seams
Piercing a standing-seam Zincalume sheet can restrict its thermal movement and may affect the cladding maker's 20-year waterproofing warranty. The proposed high-tensile aluminium clamps, similar to S-5 designs, grip the raised seam. Installers tighten stainless-steel bolts to the specified torque without puncturing the sheet. Check clamp compatibility and warranty conditions with the roof supplier.
3. Design for local wind uplift
The northeast monsoon from October to December can bring severe gusts to southern Andhra Pradesh. The example uses design wind speeds of 44 to 50 m/s, up to 180 km/h, under IS 875 Part 3. Modules follow the roof's 8-degree pitch. In the cited comparison, flush mini-rails reduce uplift pressure by over 60% against tilted ground-mount racks. The actual clamp spacing and edge setbacks require a project-specific wind calculation.
Keep fixings out of roof valleys. They carry rainwater, and punctures can lead to leaks over stored goods during monsoon storms. Agree the fixing detail with the roof manufacturer before work starts.
Schedule charging around solar output
The example connects the 250 kWp plant to the warehouse's charging loads. Control settings matter because several vehicles charging together can raise demand charges:
- Stagger reach-truck charging: An energy controller sequences 8 x 10 kW three-phase chargers. The model increases charging between 10:00 AM and 2:30 PM as solar output rises, aiming to avoid a contract maximum demand (CMD) surcharge.
- Provide delivery charging: The illustrative layout includes a carport over employee parking for 20 electric three-wheelers. It has five dual-gun 7.4 kW AC Type-2 chargers connected to the solar bus. See our solar carport and EV charging guide for the layout considerations.
The 250 kWp warehouse cost model
The worked DC plant has 431 Tier-1 DCR-compliant 580 Wp N-type TOPCon bifacial modules and two 110 kW Sungrow three-phase string inverters. At 250 kWp, the southern Andhra Pradesh forecast is about 3,62,000 units each year, or 1,448 kWh per kWp. A roof survey and hourly load data are needed to test those assumptions for your site.
| Measure | Grid-only case | 250 kWp solar case | Effect in the model |
|---|---|---|---|
| Grid electricity bought each year | 5,40,000 kWh | 1,95,000 kWh | 63.9% fewer utility units |
| Solar electricity produced each year | 0 kWh | 3,62,000 kWh | 1,448 kWh/kWp yearly yield |
| Solar used on site | N/A | 94% (~3,40,280 kWh) | Used by forklifts, conveyors and lights |
| Solar exported for credit | 0 kWh | 6% (~21,720 kWh) | Export on quieter Sundays |
| Average monthly power bill | ₹4,25,000 | ₹1,60,000 | ₹2,65,000 less each month |
| Annual utility bill | ₹51,00,000 | ₹19,20,000 | ₹31,80,000 lower annual bill |
| Yearly diesel generator use | ~8,400 Litres | ~6,200 Litres | 2,200 litres avoided (₹2,15,600) |
| Yearly O&M and cleaning allowance | ₹0 | ₹95,000 | Covers quarterly checks and washing |
| Net annual benefit | Not applicable | Not applicable | ₹33,00,600 per year |
The table also models 2,200 litres of avoided diesel use worth ₹2,15,600. A standard grid-tied solar inverter stops during a grid outage, so that saving requires a compatible generator and solar control arrangement. Verify the site's actual shutdown hours and controls before including it in your return estimate.
After the June 2026 ALMM List-II change, we prepare new commercial quotations with DCR panels unless a verified exemption applies. The assumed DCR premium is ₹9 to ₹12 per Wp. The illustrative ₹1,08,50,000 turnkey cost (₹43,400 per kWp) includes Tier-1 modules, two 110 kW inverters, seam clamps, perimeter lifelines, net-metering synchronisation and CEIG approvals. Confirm actual cost through a site quotation.
| Financial measure | Without tax effect | With 40% accelerated depreciation |
|---|---|---|
| Installed project cost | ₹1,08,50,000 | ₹1,08,50,000 |
| Year 1 tax saving (40% AD at 25% tax) | ₹0 | ₹10,85,000 |
| Capital after modelled tax saving | ₹1,08,50,000 | ₹97,65,000 |
| Annual cash benefit | ₹33,00,600 | ₹33,00,600 |
| Calculated simple payback | 3.28 Years | 2.95 Years |
| Modelled internal rate of return (IRR) | 27.8% | 32.4% |
| Modelled net profit over 25 years | ₹7.16 Crores | ₹7.27 Crores |
Monitor faults and protect stored goods
A warehouse may hold tens of crores of rupees of client stock. Agree the roof plant's electrical protection and maintenance access with the insurer and fire-safety team before installation. The worked design includes:
- Arc fault interruption (AFCI): The specified Sungrow inverters have an AFCI function intended to detect DC series arcing within 100 milliseconds and disconnect the affected string. Test settings at commissioning; no device removes every fire risk.
- Roof lifelines: Permanent stainless-steel fall-arrest lines along the ridge are specified to EN 795 Class C. Trained cleaners and inspectors clip their harnesses to the line and follow the site's working-at-height procedure.
- String monitoring: A mobile view gives the plant manager generation, string current and performance ratio (PR) data. Alerts help identify a disconnected string or unusual soiling so the maintenance team can investigate.
The table assumes 40% accelerated depreciation on written down value under section 33 of the Income-tax Act, 2025. A company's tax position determines whether it can use the deduction. Confirm the current rate and your eligibility with a chartered accountant. Figures are indicative, schemes change, and Ray2Volt does not give tax or investment advice.
Frequently asked questions
How do you check whether a PEB roof can carry solar?
Start with drawings and a structural survey. The example's module and mini-rail assembly adds 11 to 14 kg per square metre, while its assumed PEB allowance is 15 to 25 kg/m2 for live and collateral loads. An engineer must verify purlins, rafters, existing services and wind uplift before approving the layout.
When should forklifts and delivery EVs charge?
Reach trucks, order pickers and delivery three-wheelers can charge at staging bays between runs. A controller can give priority to sunny hours while staggering chargers to limit peak demand. Compare the fleet timetable with solar output and include charging losses in the cost model.
How can panels be fixed without blocking roof drainage?
On standing-seam sheets, compatible clamps grip the raised seam without making holes. Trapezoidal sheets may need approved fasteners through raised crowns with EPDM gaskets, clear of drainage channels. Ask the roof manufacturer to confirm which detail preserves its warranty.
Could a warehouse owner lease unused roof area?
A logistics park with 1,00,000+ sq ft of roof and little internal demand may discuss a roof lease or open-access RESCO PPA. An independent power producer (IPP) could rent the space or sell output to nearby tenants. Check roof rights, grid approvals and contract terms before assuming rental income.
What payback should a warehouse use for planning?
Businesses typically plan for 3 to 5 years after a site audit. This table gives 3.28 years without tax effects and 2.95 years with its tax assumption, using an illustrative APSPDCL tariff of ₹8.80 to ₹10.20 per unit. Section 33 of the Income-tax Act, 2025 allows 40% accelerated depreciation on written down value where eligible. Verify the current tariff and tax treatment with your chartered accountant. Ray2Volt does not give tax or investment advice.
Ray2Volt Solar Private Limited
We design, install, and service rooftop solar for homes and businesses across Tirupati district and Andhra Pradesh, from PM Surya Ghar residential systems to commercial and industrial plants. Every enquiry starts with a free power audit.
Check your warehouse roof for solar
Share your building drawings and recent power bills. We can review structural capacity, charging demand and grid connection, then prepare a site-specific feasibility and savings estimate.
