The leisure battery is charged by both the alternator and solar panel. I used a solar panel kit containing everything needed except a battery.
I opted for a 110 watt flexible monocrystalline panel. Monocrystalline is a bit more efficient compared to polycrystalline but also a bit more expensive. I choose a flexible panel so I could mount it low profile on the roof. Flexible panels have downsides however. They are supposed to be less durable and because they are mounted directly to a surface, they heat up more in the sun. Heat reduces efficiency of solar panels.
The pop-up roof that the solar panel is mounted to, has a profile built in for structural strength. I had to level that out and the best way I could think of was using X-trem isolation. X-trem is resistant to heat and has a closed cell structure so it doesn’t absorb water. I used Sikaflex 252 to glue everything down. The glue came with the solar panel kit. It’s super strong but terrible stuff to work with. It’s very thick.
The wiring to the solar charger is run through the rubber grommet that passes the stock wiring to the hatch to avoid having to drill holes. The kit came with a Victron MPPT 75/15. It’s an excellent charge controller and it’s big enough to add a second solar panel if needed. I added a VE.Direct Bluetooth Smart dongle so I can monitor the performance of the system on my phone.