The 123-STG-72D62 in the Field: Published Specifications, Measured
Every rating on the 123-STG-72D62 is calculated. So we put one to work at a remote monitoring site in the southern Nevada desert and let its inverter keep score, every five minutes for 75 days. Wherever the site put a specification to the test, the system met it or beat it.
- System
- 123-STG-72D62 Tri-Brid™, 7.36 kW solar, 31.8 kWh LFP, 10.8 kW diesel
- Site
- Remote monitoring site, southern Nevada desert
- Record
- July 1 to September 13, 2026, logged every five minutes
- Solar produced
- 1,863 kWh
- Diesel supplied
- 50 kWh, less than 3% of the energy used
- Engine hours, September 1 to 13
- About 4 of 312
Published Specifications, Checked Against the Logs
A calculated rating is only as good as its assumptions. The table sets five of the 123-STG-72D62’s published figures beside what its inverter actually recorded, and says what each difference means.
| Specification | Case study | The difference |
|---|---|---|
| Solar harvest31.6 kWh a day | 34.7 to 38.1 kWh a day, September 8 to 13; up to 38.7 kWh in August | 10% to 22% more than rated. The rating assumes a 4.3 sun-hour day; this site averages 7.1 sun-hours in August and 6.2 in September, and the array was still throttled once the battery filled. |
| Engine-off break-even1.32 kW | Daily loads up to a 1.51 kW average with no diesel energy, August 20 to 31 | 14% more load than the break-even with the engine off, because the site had more sun than the rating assumes. |
| Array output7.36 kW nameplate | 7.1 kW peak | Within 4% of nameplate. Solar panels give up some output as they heat, and this was late-summer desert heat. |
| Batteryruntimes planned on 15.9 kWh, half of the 31.8 kWh bank | 17.1 to 18.8 kWh delivered each night, September 8 to 13; lowest charge 34% | 8% to 18% more energy than planned each night, with a third of the bank still in reserve. |
| Diesel runtimea generator alone runs 24 hours a day, 312 hours over September 1 to 13 | About 4 engine hours, in three runs | About 99% fewer engine hours than a generator alone. |
Measured by the system’s inverter every five minutes, July 1 to September 13, 2026. Specifications as published on the 123-STG-72D62 product page.
Why the Solar Beat Its Rating
The published 31.6 kWh is set on a 4.3 sun-hour day, a conservative average. NASA’s long-term record for this part of Nevada is 7.1 sun-hours in August and 6.2 in September, so the array had more to work with than the rating assumes.
It also had more than the site could use. On loaded days the battery reached full charge in the early to mid-afternoon, and the controller throttled the array back to the load. The 34.7 to 38.1 kWh recorded is what the site needed, not everything the panels could make.
That surplus is margin: capacity held in reserve for shorter winter days, a dusty array or a heavier load.
Above Break-Even, Engine Off
The product page says that below 1.32 kW, the sun covers the whole load and the system runs with the engine off. At this site, the load regularly ran above that line.
From August 20 through August 31, daily load reached as much as 36.3 kWh, a 1.51 kW average, and the diesel engine supplied no energy at all.
From September 1 through 13, a generator-only system would have run 312 hours. The 123-STG-72D62’s engine ran three times, for about four hours in total.
The Diesel, Doing Its Job
A Tri-Brid™ system does not eliminate the diesel. It keeps the engine in reserve for the days solar cannot cover.
On September 6, the array produced 12.2 kWh while the load used 22.1 kWh. By 5:14 the next morning, the battery was at 31%. The engine ran from 5:14 to 8:04 AM and stopped with the battery at 56%. By 12:29 PM, the sun had the battery full again.
That is the design working as specified: solar and storage carry the load, and the engine runs only to make up the difference.
What It Means for Your Site
Engine hours drive fuel deliveries, oil changes and service visits. A system that holds its generator in reserve reduces all three, and the benefit grows the more remote the site.
Sun, load and season set every result. That is why our ratings are calculated on conservative assumptions, and why the 123-STG-72D62’s field record came in above them. Start with your load and location in the sizing tool.
PDF This page with the 123-STG-72D62 engineering sheet, to print.
The system tested123-STG-72D62The deepest Tri-Brid™ bank, 31.8 kWh, behind sixteen panels: 9.4 days between refuels at 6 kW.View the specifications
The 123-STG-72D62 in service.
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