How much diesel does a hybrid power system save compared with a generator?

The saving comes from the generator not running, and how much that is worth depends on three site-specific variables: the load profile, the solar resource at that location and season, and how long the unit is deployed. Model your own case with the V-Trail calculator, enter your load, hours per day, location and analysis period and it will return the fuel, cost and emissions comparison for your site.

What is structurally different about a hybrid system, and holds regardless of the site:

• A diesel generator runs continuously to serve a variable load, spending much of its life lightly loaded, which is where it is least efficient and where wet stacking and maintenance problems originate. A 27 kVA set carrying a 4 kW load is running at under 20% of its rating.
• A hybrid system serves the load from solar and battery, and starts the generator only when the battery needs recharging. The generator runs at high load for a short period rather than at low load continuously.
• Fuel is not the only cost avoided. Refuelling trips, service hours, and the emissions and noise footprint all scale with generator run hours. On a remote site, the refuelling logistics can exceed the fuel cost.
• The measure to ask for is generator run hours per week, not litres per hour. Run hours are what drive fuel, servicing and site visits together.