Overview
How this machine carries the load.
A new cell site is often ready to go on air before utility power reaches it, and until it does, a temporary diesel generator runs it around the clock. 123-SG-7S82-40 puts that site on air as two units working as one system: a sixteen-panel solar and battery trailer that carries the site, and a standalone 40 kW diesel generator that steps in only when the sun and the battery cannot.
The solar trailer is rated for 12 kW continuous, with surges to 24 kW for motor and compressor starts. Its 7.36 kW array brings in 31.6 kWh on an average day to a 30.4 kWh lithium iron phosphate bank. Below 1.32 kW the site runs on sun and battery alone, indefinitely, with the engine off.
Above that, the 40 kW generator does two jobs at once: it carries the load and recharges the bank at the inverter's full charge rate, then shuts down. At a steady 6 kW that is about 6.2 engine hours a day and 15.91 days between refuels of its 140-gallon tank, against 7.92 days for the same generator carrying the load alone — 8.36 gallons a day instead of 16.8. At 4 kW the tank lasts 27.62 days and at 2 kW 107.9, while the generator alone still refuels every 7.92. Both engines are read by the same fuel rule: their own published figures, held at the lowest one below it. At a remote site every refuel is a truck, a driver and a day on the road, so the days between refuels are what make this the cost-effective way to keep the site on air.
Because the generator travels on its own trailer, either unit can be serviced or replaced without taking the other offline, and the solar trailer can work alone where an engine is not allowed. Output is 120/240 V or 120/208 V at 50/60 Hz, with a 5 ms transfer.
Features and benefits
- Sixteen 460 W panels, 7.36 kW — Loads around a kilowatt run with the engine off.
- Standalone 40 kW diesel, 140-gallon tank — 15.9 days between refuels at 6 kW.
- 30.4 kWh lithium iron phosphate bank — Quiet nights on sites with neighbours or noise limits.
- A solar trailer and a generator trailer — One site, two independent machines, and no single point of downtime for maintenance.
Performance
Performance across the load range.
Zero to 12 kW, the rated maximum.
engine hours per daydiesel, US gallons per daythe array carries the whole dayrated continuous output
| Loadcontinuous, 24 h | Solar generationthe array, per day | Battery only | Daily drawload × 24 h | After solar | Days of autonomy | Generator | Engine runsa day × each | Charge setting | Days on a tank |
|---|---|---|---|---|---|---|---|---|---|
| 1.32 kWsolar break-even | 31.6 kWh | 11.12 h / 15.57 h | 31.6 kWh | covered | indefinite | 0 h/day | none | 258 A | — |
| 2 kW | 31.6 kWh | 7.33 h / 10.27 h | 48 kWh | 16.4 kWh | 0.9 days | 1.15 h/day | 0.9 × 1.2 h | 258 A | 107.9 days |
| 4 kW | 31.6 kWh | 3.67 h / 5.13 h | 96 kWh | 64.4 kWh | 0.23 days | 3.98 h/day | 3.2 × 1.2 h | 258 A | 27.6 days |
| 6 kW | 31.6 kWh | 2.44 h / 3.42 h | 144 kWh | 112.4 kWh | 0.13 days | 6.18 h/day | 5 × 1.2 h | 258 A | 15.9 days |
| 8 kW | 31.6 kWh | 1.83 h / 2.57 h | 192 kWh | 160.4 kWh | 0.09 days | 7.94 h/day | 6.4 × 1.2 h | 258 A | 11.2 days |
| 10 kW | 31.6 kWh | 1.47 h / 2.05 h | 240 kWh | 208.4 kWh | 0.07 days | 9.39 h/day | 7.5 × 1.2 h | 258 A | 8.6 days |
| 12 kW | 31.6 kWh | 1.22 h / 1.71 h | 288 kWh | 256.4 kWh | 0.06 days | 10.6 h/day | 8.5 × 1.2 h | 258 A | 7.1 days |
Every load here runs continuously, and the day is 24 hours — daily draw is the load × 24 h, so 2 kW is 48 kWh. A load that runs an 8-hour shift draws a third of the figure shown and lasts three times as long. Battery-only hours are given at both state-of-charge settings. Solar is a daily energy offset, not an instantaneous power match — over a day it balances, within a day it is not a guarantee of cover.
The engine starts at 30% state of charge (a 70% depth of discharge) and stops at 80%, putting 15.2 kWh back into the bank on each run while it carries the load. The engine runs a day follow from that at each load.
Case study
Against the 40 kW generator running alone.
At 6 kW around the clock, its own 40 kW generator — the one telecom sites use for temporary power — would carry the site alone at 15% of its rating, 24 hours a day. 123-SG-7S82-40 runs its engine 6.2 hours a day — 74% fewer engine hours — and burns 50% less diesel: 8.4 US gallons a day against 16.8 US gallons, and 15.9 days between refuels against 7.9 days.
PDF The full engineering sheet with this case study, to print.
| Loadcontinuous, 24 h | 40 kW alonediesel a day, engine 24 h | Days on a tank40 kW alone | This systemengine hours a day | Diesel a daythis system | Days on a tankthis system | Engine hours saved | Diesel saved |
|---|---|---|---|---|---|---|---|
| 2 kW5% of the 40 kW | 16.8 gal | 7.9 days | 1.15 h | 1.2 gal | 107.9 days | 95% | 93% |
| 4 kW10% of the 40 kW | 16.8 gal | 7.9 days | 3.98 h | 4.8 gal | 27.6 days | 83% | 71% |
| 6 kW15% of the 40 kW | 16.8 gal | 7.9 days | 6.18 h | 8.4 gal | 15.9 days | 74% | 50% |
| 8 kW20% of the 40 kW | 16.8 gal | 7.9 days | 7.94 h | 11.9 gal | 11.2 days | 67% | 29% |
| 10 kW25% of the 40 kW | 16.8 gal | 7.9 days | 9.39 h | 15.4 gal | 8.6 days | 61% | 8% |
| 12 kW30% of the 40 kW | 20.2 gal | 6.6 days | 10.6 h | 18.9 gal | 7.1 days | 56% | 7% |
The 40 kW generator carries the load alone, 24 h a day with no sun and no battery, on its own 140 gallon tank (133 usable). Both engines are read by the same rule: their own published fuel figures, a straight line between them, and below the lowest published point that point’s burn — for the 40 kW, 25% of its rating. No lighter-load figure is invented for either engine. This system’s figures are the performance table above.
Size it for your site
Your load, on 123-SG-7S82-40.
Most sites swing between a low and a high. Enter both, and the hours a day spent at the high, and the figures follow your day rather than a flat worst case; add your diesel price for the fuel bill. The load is yours — nothing is assumed until you enter it, and nothing that names you is kept; the PDF button builds the engineering sheet from the figures you enter.
PDF The engineering sheet, with page two worked out for your load.
| Held flat at your high24 h at the high load | Your dayhigh and low, as entered |
|---|
Read from the performance table above: engine hours and fuel follow the day's energy, so your day is read at its average load; solar is the published daily figure; battery-only hours are the published bank at your high load. A load held for 24 hours is the worst case at that level. With no days entered it runs indefinitely; a week and a year are your day repeated, at the same sun.
Gallery
On site and on the road.
Applications
Where this configuration is deployed.
Application
Where this configuration applies.
Application · CommunicationsContinuous power without continuous diesel operationSolar and battery storage carry the load for much of the day, so the diesel engine runs only when needed. For a steady 5.7 kW load at 5.2 peak-sun hours, the 123-SG-7S82-40 is calculated to cut engine runtime from 24 to 5.8 hours a day.Read the article