Why the hybrid wins
A lightly loaded engine still burns fuel just to keep spinning. Charging the battery gives it a short, useful job near its efficient load.
Part-load runninglong + wasteful
Hybrid chargingshort + efficient
Free UK off-grid power calculator
Run the generator less. Power everything off-grid.
Let a 48V battery carry your tools, pumps, lights and sockets. Your generator switches jobs—charging hard for short, efficient bursts instead of running for hours at low load.
Cut diesel + engine hours Reliable 230V without mains
Calculate my savings Real hourly PVGIS data · No signup
Hybrid power flow
System onlineSolar
Generator
Inverter
charger
48V
battery
230V
loads
Short + hard
Generator charge runs
Quiet + steady
Battery powers the site
Model your real site
See what supplies the power—month by month.
Choose your loads, system size and location. The result updates live with the solar share, generator charge hours and estimated annual saving.
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Why the system works
Not generator versus solar. The right job for each.
No mains. Normal 230V power.
The battery and inverter supply the loads you actually need, silently and without waiting for a grid connection.
Tools
Cold
Pumps
Wi-Fi
Sockets
Lighting
Built around December, not brochure weather.
Summer is easy. We use your exact map pin and a full year of hourly solar data to show the winter generator requirement before you buy anything.
- Exact UK location
- Hour-by-hour simulation
- Winter backup shown clearly
Turn the result into hardware
Ready to build your 48V off-grid system?
Common Questions About the Off-Grid Calculator
It runs an hour-by-hour battery simulation against a typical meteorological year of real solar data (PVGIS) for your area. Your daily consumption drains the battery on a realistic 24-hour profile, solar charges it as the sun actually behaves month by month, and the result is how long the system runs off-grid in each month of the year — including December, which is the number that matters in the UK.
These are months where solar and the battery cover your selected loads without meaningful generator support. The monthly power-mix cards show the detail: how much usable energy comes from solar and how much the generator supplies through short battery-charging runs.
In a 48V hybrid system the generator does not power your appliances directly — it charges the battery through the inverter-charger, running for short bursts at high load. That is the efficient way to run a genset: a couple of hours at its sweet spot instead of all day at part throttle. The calculator simulates the generator auto-starting at 20% battery and charging to 80%, then compares those run-hours against your current routine of running it whenever you need power.
From roughly April to September, usually yes — most sensibly sized systems cover daily use entirely and the genset stays off. Through December and January in the UK, the honest answer for most loads is a hybrid: the battery carries the day and the generator tops it up for a few hours a week. The calculator shows you exactly how many hours, for your location.
Real 48V off-grid kit: Fogstar 48V lithium batteries (with self-heating and built-in fire suppression), Victron MultiPlus and MultiPlus-II inverter-chargers, Victron MPPT solar charging and Lynx distribution, monitored remotely with a Victron Cerbo GX. The charger power shown for each tier is the genuine Victron charge rating at 48V.
It is free and there is no sign-up. Solar data comes from PVGIS, the European Commission's solar resource database, and the battery maths is the same simulation our configurator uses. Treat the outputs as good planning estimates rather than guarantees — panel orientation, shading and unusual weather all move real-world results.