An electric truck depot in a high-irradiance market can cut charging cost by coupling a PV array to the charger network, with a battery buffer and a diesel genset hybrid fallback for cloudy days and peak demand. The Dongfeng TE46 4x2 tractor carries a 282 kWh CATL LFP pack and runs 220 km at GCW 42 t, so a single truck returning from a day shift needs about 200 kWh to refill. This guide sizes the PV array per truck, the buffer and the genset, then lays out capex, opex and a 5-8 year payback math for sun-rich import markets.
A 282 kWh daily refill at about 85 percent system efficiency needs roughly 332 kWh of generation. In a market with 5.0 kWh per kWp per day of insolation, that is roughly 66 kWp of panels per truck if you charge only from sun. Most fleets blend sun with grid, so a 30-40 kWp array per truck covers 40-60 percent of demand and trims the biggest opex line. Panel cost runs $0.40-$0.70 per Wp, so 35 kWp is about $14,000-$25,000 per truck before inverters.
The buffer stores midday surplus for night charging and shaves demand spikes that would otherwise trip the depot breaker. Size it to one truck pack plus 20 percent, about 340 kWh, using second-life or new LFP at $120-$180 per kWh, or $40,000-$60,000 for a ten-truck depot. A correctly sized buffer lets you charge on a smaller grid connection and avoid a costly transformer upgrade.
Where the grid is unreliable, a 150-200 kW diesel genset backs the chargers during outages and cloudy spells. Run it only for the gap the PV and buffer cannot cover, which can be under 500 hours a year, keeping fuel under $15,000 annually for a mid-size depot. The hybrid design means you never strand a truck, but the genset should be the last 10 percent of energy, not the base load.
| Scenario | Added capex per truck | Opex energy $/km | Payback |
|---|---|---|---|
| Grid-only depot | $25,000-$40,000 | $0.10 | Baseline |
| Solar plus buffer | $18,000-$30,000 | $0.05-$0.07 | 5-7 years |
| Solar plus buffer plus genset | $25,000-$40,000 | $0.06-$0.08 | 6-8 years |
| Full off-grid solar | $45,000-$70,000 | $0.04 | 7-9 years |
Take a fleet of ten TE46 tractors at 70,000 km a year each. Grid charging at $0.10 per km is $70,000 a year in energy. A solar-plus-buffer depot at $0.06 per km cuts that to $42,000, saving $28,000 a year. Against added capex of $200,000 for the array and buffer, payback lands near 7 years, faster where industrial tariffs exceed $0.15 per kWh. The buffer also delays a transformer upgrade worth $50,000-$120,000, pulling the effective payback inside 5 years.
Nigeria has strong irradiance and uneven grid supply, which makes a solar-hybrid depot attractive for Lagos and Kaduna logistics yards running the TE46 on regional loops. Review electric trucks in Nigeria for tariff and connection timelines.
The model page for the Dongfeng TE46 electric tractor carries the 282 kWh pack, 282 kW motor and GCW 42 t rating your energy model needs.
The PV array feeds a string inverter sized at 1.2 times the array nameplate, so a 35 kWp array needs a 40-50 kW inverter to avoid clipping on cool, bright mornings. The charger group needs a separate AC-DC stage; size the site controller to balance array, grid and buffer so the trucks charge on sun first and grid only for the gap. A 30-40 kWp array per truck with a 340 kWh buffer typically cuts grid draw by 50-60 percent, which is the point where the depot payback drops below 7 years. Use a controller with per-bay metering so energy cost per truck stays auditable for the contract.
Solar depots are quiet to run but need discipline. Wash panels every 6-8 weeks in dusty markets; a 10 percent soiling loss on a 35 kWp array is 3.5 kWp of lost generation, about $300 a year per truck. The buffer needs a yearly capacity test and cell balancing, the same service as a second-life pack. The diesel genset needs a monthly test run of one hour so it starts when called, and an annual load bank check. Budget $1,500-$3,000 per truck per year for O&M, well below the $10,000-$15,000 it saves on energy.
| Item (20 TE46 tractors) | Grid only | Solar plus buffer |
|---|---|---|
| Added capex | $0 | $400,000 |
| Annual energy cost | $140,000 | $84,000 |
| Annual saving | - | $56,000 |
| Payback | - | 7 years |
| Transformer upgrade avoided | $80,000 | $0 (buffer covers it) |
Against $400,000 of added capex, the $56,000 annual energy saving gives a 7-year payback, but the buffer also avoids an $80,000 transformer upgrade, which pulls the effective payback inside 5 years. In Nigeria, where the industrial tariff can reach $0.18 per kWh and outages are common, the hybrid design often pays back faster than the table shows because the genset runtime stays under 500 hours a year.
Spread the capex with a 5-year equipment lease at 8-10 percent and the monthly payment is about $8,000-$10,000 against $11,000-$14,000 of monthly energy saving, so the depot is cash-positive from month one. Some markets let the solar asset sit off the truck balance sheet, keeping the FOB and the working capital for vehicles separate. Importers should price the lease with the same bank that funds the trucks so the two payments net into one fleet facility.
In Nigeria and similar markets, solar depot capex can stack with import duty relief, renewable energy grants and green-bond financing, which changes the payback sharply. A 30 percent solar grant on the $400,000 array cuts added capex to $280,000 and the payback to under 5 years; a green bond at 6 percent instead of 10 percent saves another $8,000 a year in interest. Importers should ask the distributor and the local development bank for the current list before sizing, because the buffer that avoids a transformer upgrade is often the line item the grant favours most. Pair the solar plan with the market page incentives so the FOB and the depot are funded as one project rather than two competing budgets.
Start with one TE46 and a 35 kWp array to learn the insolation and the load shape, then add arrays in 35 kWp blocks as trucks arrive. The buffer scales the same way, one 340 kWh module per ten trucks, so the depot never over-builds. This block approach keeps the per-truck payback steady at 5-8 years and avoids a single large outlay that sits idle while the fleet ramps. Operators that scale in blocks report 10-15 percent better utilisation of the solar asset than those who build the full array on day one for trucks that arrive in month twelve, and metering each block separately proves the saving per truck to the finance team.
The three errors that break solar depot payback are oversizing the array for a fleet that has not arrived, skipping the buffer to "save capex" and then paying for a transformer upgrade, and forgetting to wash panels in dusty climates so generation silently falls 10-15 percent. Size to today's trucks plus one block of headroom, always include the buffer, and put panel washing on the same monthly checklist as the charger torque check. Avoid those three and the 5-8 year payback in the table holds even when the tariff stays flat, which is the case most importers should plan for.
Ready to electrify your fleet? Contact Shaanxi Fenghan Trading — authorized Dongfeng EV truck exporter. WhatsApp: +86 153 1943 1311 | Email: sales@fenghan-trade.com | dongfengevtrucks.com
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