1 voltage meter for both solar panel and battery

[Clive S]

I have bought one of these (ebay item-251214397202) 0.56" Digital Voltmeter Green LED Panel 3/2-Wires DC 0-100V 4-30V Power Monitor. I want to read the voltage of a battery and a solar panel fitted to my caravan. What switch do i need and how would i wire this circuit please.

Not sure what you mean by "what switch" but these little meters are quite good for the price. Just connect the red and yellow wire to a + 12volt and the black to the -ve and it will read the voltage of the battery. If you want to read above about 30V then you have to connect the red wire to a source below 30V and the yellow wire to what you want to measure up to 100V. The -ve has to be to be the same for both the supply and the higher voltage you want to measure.
It would of course be prudent to put a fuse in line to protect the cables ..Clive