Technical tool · free sizing
Solar generator vs diesel calculator
Enter your site's consumption and project duration. This solar generator vs diesel calculator estimates the real cost of a diesel generator, the litres of fuel you avoid and the payback point of a mobile solar power unit. Every assumption is shown, so you can redo the calculation yourself.
Diesel costs you
11,537 EUR
over 12 months of project
Diesel avoided
5,253 l
≈ 14.1 tonnes of CO₂ not emitted
Solar coverage
100%
the rest stays on the backup genset
Recommended model: Centrală fotovoltaică mobilă VOLTRAIL
For 45 kWh per day in your location county, where one kWp yields 1300 kWh per year, you need 30.0 kWp. Centrală fotovoltaică mobilă VOLTRAIL produces 107 kWh per day on average and covers 100% of the annual load, calculated month by month. The rest stays on a backup genset or on the grid.
Mind the winter. In January the same unit produces only 55 kWh per day on average, that is 100% of your load. If the project runs through the winter months, we either size up or plan a backup genset for the peaks. The annual average alone leads to undersizing.
Specifications of VR-30 – VR-150 →| Cost over 12 months | Diesel generator | With VOLTRAIL |
|---|---|---|
| Fuel | 7,880 EUR | 0 EUR |
| Maintenance and wear | 3,657 EUR | covered by warranty |
| Fuel avoided | — | 7,880 EUR |
Want the calculation checked by an engineer?
We send the full sizing, with your hourly load profile and the monthly output estimated for the exact location.
Calculation assumptions
- Specific genset consumption: 0.32 litres per kWh produced, a typical value at partial load.
- Genset maintenance and wear: 0.89 EUR per running hour.
- Emissions: 2.68 kg CO₂ per litre of diesel burnt.
- Photovoltaic yield: 1300 kWh per year per kWp installed in your location county, provisional until PVGIS data is integrated.
- Rates are derived from Romanian list prices at a reference rate of 5.05 RON/EUR.
- The calculation excludes the cost of hauling fuel to site, which in practice tilts the balance further.
Starting points
Typical loads by project type
If you do not know the exact load, start from the values below and adjust in the calculator. We collected them from real projects, not from datasheets.
Why a diesel generator alternative changes the numbers
A diesel generator looks cheap to buy, but the real cost shows up over the life of the project. Every kWh produced means fuel burned, filters replaced, service hours and fuel hauled to the location. On a site with no grid connection, these costs run month after month and never stop. A mobile solar power unit moves the spend from fuel into equipment: you pay for the unit once, and the energy comes from the sun.
The calculator above shows exactly that difference. It does not compare a single panel to a generator, it compares two ways of powering the same location for the whole job. The result is not a marketing promise, it is a figure you can reproduce yourself, because every assumption is on the table.
How much fuel does a diesel generator burn on site
At partial load, a genset burns around 0.32 litres of diesel for every kWh delivered. For a typical load of 45 kWh per day, that is almost 14.4 litres per day, more than 5,000 litres over a year of work. On top of that come maintenance and wear, which rise with operating hours. A well sized solar generator takes over most of this load and leaves the diesel unit only as backup for peaks or for short winter days.
How to size a mobile solar generator correctly
The common mistake is to size for the annual average production. Solar yield is not uniform through the year: in June and July it is several times higher than in December. If you choose the unit by the average, you run short in winter. That is why this calculator sizes for the month with minimum production and, where relevant, flags the need for a backup unit. It is how you avoid the surprise in the first winter on site.
Frequently asked questions
Can a solar generator fully replace a diesel generator on a construction site?
Yes, for most site setup loads: lighting, the site office, light tools and surveillance. The unit is sized for the weakest month, and a backup generator is kept for peaks or heavier work. The calculator shows exactly what coverage you get month by month, so the decision is on numbers, not estimates.
How much do I save switching from diesel to a mobile solar power unit?
The saving comes from avoided fuel plus the maintenance and wear of the diesel generator. On a load of 45 kWh per day for a year, a diesel generator burns more than 5,000 litres of fuel. Enter your consumption and project duration and the calculator gives the exact figure, plus the litres and tonnes of CO₂.
How do I size a solar generator for my consumption?
Start from the daily consumption in kWh and the solar yield of your location. The unit is chosen so it covers the load even in the winter month with minimum production, not just the annual average. The average alone leads to undersizing and to surprises in December.
What happens in winter, when there is less sun?
Production drops in December and January. That is why we size for the weak month and, where needed, add a backup generator for peaks. The calculator shows winter production separately, so you can see whether the project runs through the cold months and how much still needs another source.
How much does a VOLTRAIL mobile solar generator cost?
Price depends on power (kWp), storage capacity and the format of the unit: solar trailer, foldable container or skid unit. Send your consumption through the form and get the full sizing and a quote for the model that fits your project.
The detailed report, by email
We send the full sizing as a PDF: load profile, estimated monthly production for your exact location, fuel avoided and CO₂ for environmental reporting. An engineer checks the figures before they reach you.