how do i charge 12 and 24 volt batteries at the same time from my solar panels i have 500 watts of solar and a 50 amp regulator...

We have built a camper van from a 7.5 tonne truck and stupid me didn't realise that the truck is 24 volt but i need to be able to charge my house batteries from the engine but they are twelve volt also i will need to charge my truck batteries from the solar any ideas cheers...

How many 12 V batteries are you charging ?
Steve