How should levelling be planned in an RV charged by solar panels?
Solar fills the battery slowly, levelling asks for a short peak current. The battery supplies that peak; keep it above the limit and finish in one go.
Solar is a source that fills the battery slowly through the day; levelling is a load that asks for a high current over seconds to minutes. The right plan is to take the energy for levelling from the battery rather than from the panel, and to keep a lead-acid/AGM battery above the 50% discharge limit. Levelling while the battery charge is in good condition, rather than the moment you arrive at the camp site, is what keeps the system working properly.
The panel is the source, the battery is the buffer
The power of a solar system, in watts, is spread across the whole day; levelling asks for a short peak current. Trying to match these two directly is the wrong setup. The panel fills the battery, and the battery supplies the levelling current. That is why the real question is not "how many watts of panel do I have" but "how far does the battery voltage drop while the jacks are running".
Practical plan
- Try to arrive at the camp site while there is daylight; levelling in the evening, when the battery is already tired, is the worst case.
- Calculate the usable capacity of your house battery realistically: roughly half the label value in lead-acid/AGM. At 50% DoD you typically get 500-1000 cycles, while at 80% DoD this is roughly halved.
- Make sure the charge controller is set correctly for the battery chemistry; a wrong charge profile leaves the battery chronically half full.
- Finish levelling in one go. Constantly changing position and levelling over and over burns unnecessary cycles.
- Remember that the Retract Jacks function also needs energy before you set off; do not run the battery all the way down.
Charging source by pattern of use
| Pattern of use | Solar on its own | What it makes sense to add |
|---|---|---|
| Long stay in the same place | Usually enough | No extra source needed |
| Moving every day | May fall short | DC-DC charging from the alternator |
| Winter and short days | Not enough | Mains charging |
| Shaded forest camp | Unpredictable | Mains or alternator |
An MPPT charge controller increases the energy taken from the panel but does not solve the peak current problem; the peak current is met by the battery in any case. A DC-DC charger, on the other hand, fills the battery along the road and is therefore the most effective addition where you move about frequently.
Where solar is not enough
Whatever the panel power, if the battery is unhealthy the system will not work properly: a battery whose internal resistance has risen collapses the voltage the moment a high current is drawn, and the jacks slow down or do not move at all. If the depth of discharge is kept high all the time, adding a panel only delays the loss. In cold weather the charge acceptance of lithium batteries falls; take this into account for winter use. If the problem comes from the cable cross section, adding a panel changes nothing; in that case the subject is voltage drop. Another limit is panel orientation: the output of a panel mounted flat on the roof falls noticeably in the morning and evening hours, and the need for levelling mostly falls in exactly those hours.
What to do
On long stationary camps solar alone may be enough; but if you move frequently, diversifying the charging source (vehicle alternator or mains charging) makes the system work far more comfortably. Make a habit of looking at the battery voltage before levelling, and measure once how far the voltage drops while the jacks are running. Take the measurement at the moment the load is highest, that is while the jacks are moving together; if the voltage recovers slowly after the load is removed, the battery is tired. Note that value down once at the start of the season and compare later measurements against it.
The full topic: Solar plant panel soiling and robotic cleaning