Quote Originally Posted by the evil twin View Post
If it ain't broke don't fix it...

You obviously have enough camping power at the moment without the Cranker so leave the Redarc

I would add a connector (if it doesn't already have one you can use) to the Battery Pack and connect the Solar there.
That will top up the Aux and the Pack.... aaand... if you use a common style connector to what you use for plugging in the pack then just plug in the Solar to charge the Aux when the Pack isn't in place.

300 watts is a lot of solar so you will need at least a 25 amp MPPT Reg or 20 Amp PWM (300 watts is on the cusp of 20 amps for MMPT).
If the Reg that comes with the panels is a reasonable one just use that (at the Battery end tho not mounted at the Panels).
True MPPT Regs are expensive and in 90 % of camping use don't add all that much charging power (the theoretical figure is up to 30% BUT you won't see anything like that outside the lab).

MPPT (under about 1,000 watt systems) is the ducks guts if you have high voltage panels (32 volts or more) or don't track the sun like roof installs on houses/vans etc.

PWM is fine if you only use 12 volt panels (18 to 20 volts or so) in parallel and track the sun a couple of times

DC DC Charging, expensive but has its place, note that it will not have much effect on your solar (just saves you having an external Reg) and as you are getting sufficient performance already is not necessary. Certainly a consideration if you want to upgrade or need to buy an MPPT.

From Victron
PWM

The PWM charge controller is a good low cost solution for small systems only, when solar cell temperature is moderate to high (between 45°C and 75°C).

MPPT

To fully exploit the potential of the MPPT controller, the array voltage should be substantially higher than the battery voltage. The MPPT controller is the solution of choice for higher power systems (because of the lowest overall system cost due to smaller cable cross sectional areas). The MPPT controller will also harvest substantially more power when the solar cell temperature is low (below 45°C), or very high (above 75°C), or when irradiance is very low.
Thanks for that, it's great help. I've already fitted a red Anderson plug from the auxiliary battery under the bonnet to the bull bar, for a future solar panel connection. As for the panel, I happen to have a good price deal on a single 300w Mono unit, but I could go smaller if too big. Both auxiliary batteries can be joined via an Anderson plug. It's not a "kit", so I'll be buying cables, connections, and regulator separately. I was thinking of getting a Redarc regulator. They have a couple already fitted with Anderson plugs, but I will look at the Victron units, as you've suggested.