Charging your camper van: combining solar, alternator and shore power
Most camper vans rely not on one, but three charging sources: solar panels, the alternator via a B2B charger, and shore power via a 230V charger. Each system has its strengths and limitations. This guide explains how to combine them into a reliable whole.
Calculate your charging strategy
Solar panels: free but unpredictable
Solar panels provide free energy without noise or fuel. On a good summer day in Southern Europe, a 200Wp panel produces around 800-1000 Wh. In winter or with cloud cover, this can drop to 100-200 Wh.
Advantages: no cost after purchase, silent, works when stationary. Disadvantages: heavily dependent on weather and season, takes up roof space, not enough as a sole source with high consumption.
Tip: solar panels are ideal as a base charge. They slowly top up your battery during the day, reducing your dependence on other sources.
Alternator (B2B charger): charging while driving
A B2B charger (battery-to-battery) converts your alternator's 12V into the correct charge profile for your battery bank. While driving, this typically provides 20 to 50 amps, depending on your B2B charger and alternator.
One hour of driving with a 30A B2B charger on a 12V system charges approximately 360 Wh. That is often enough to supplement daily use if you drive regularly.
Important: a B2B charger is essential for lithium batteries. You cannot connect a lithium battery directly to the alternator for two reasons: the charge profile differs from lead-acid, and lithium batteries have very low internal resistance which can force the alternator to deliver maximum output. At idle or low speeds this can cause the alternator to overheat and fail. A B2B charger protects both the battery and the alternator.
Shore power (230V charger): fast and reliable
On a campsite with a power hook-up, a 230V battery charger can fully charge your battery bank. A good 30-50A charger fills a 200Ah lithium battery in 4-7 hours.
Shore power is also needed for heavy consumers you don't want to run from your battery: air conditioning, hair dryer or a washing machine.
Note: many campsites in Europe have limited amperage at the power post (6A or 10A). A 50A battery charger at 12V draws about 700-800 Watts from the post. With a 6A campsite connection (1380W) this usually works, but if the fridge and boiler also run on 230V the campsite breaker may trip.
Downside: you depend on infrastructure. When wild camping or on small campsites, shore power is not always available.
Combining all three sources
The ideal strategy combines all three:
Solar panels cover basic daytime needs (lighting, fridge, phone charging).
The B2B charger supplements on driving days. One hour of driving often compensates for half a day's consumption.
Shore power is used to fully charge when available, especially after several cloudy days.
The Super Wiring Wizard automatically calculates how much you need from each source based on your consumption profile and travel pattern.
Common mistakes
Relying solely on solar: even in Southern Europe there are consecutive cloudy days. Always plan a second source.
Not installing a B2B charger: you are driving anyway, so why not use that energy? A B2B charger is one of the most cost-effective investments.
Undersized shore power charger: if you only stay at a campsite for a few hours, you want to charge quickly. A 10A charger takes 20 hours to fill a 200Ah battery.
No coordination between chargers: when multiple sources charge simultaneously, one charger can raise the voltage causing the other to stop charging before the battery is full. Prevent this by choosing chargers that communicate with each other via a shared protocol (for example, linked charge controllers from the same manufacturer). This synchronises their charge phases and ensures optimal use of each source.
Calculate your charging strategy
Use our free tools to calculate your charging times and simulate your energy balance.
Frequently asked questions
- Can I go without solar panels?
- Yes, if you drive regularly (B2B charger) and/or frequently stay at campsites with shore power. But solar panels give you more freedom when wild camping and cost nothing after purchase.
- Can I use all three sources simultaneously?
- Yes, most modern charging systems (e.g. Victron) support this. The battery bank accepts current from all active sources until the maximum charge rate is reached. Just ensure the total charge current does not exceed your battery's rating (usually max 0.5C for lithium).
- How many solar panels do I need?
- That depends on your daily consumption and travel area. As a rule of thumb: 150Wp per 500 Wh daily consumption in Southern Europe (summer). The extra 50% margin ensures you not only cover daily use but also replenish your battery. In Northern Europe or winter you need double. Use the Super Wiring Wizard for an exact calculation.
Related guides
Other guides related to this topic.