I have some basic questions about DV volts to AC volts conversions and how this applies to wattage. Here is where I will begin I took some of those solar lawn lights removed the PV panels, connected them together and get 15 -18 DCVs but its not enough to even power a single item the runs off of say 12 DC volts. This is because of wattage? I have a digital volt ohm meter and do not know how to test for wattage or amps. I do see mili amps on it I guess but not sure. If a guy was to take a solar panel the could produce say 60 watts how many 12 volt batteries would be needed to power 2 or 3 items that use 120 volts and get converted down to 12 volts. You know like cordless phone charges, routers things like that. So if I have say 4 item on my computers routers etc. how many 12 volt batteries and a panel of what wattage would I need to keep the items running 24 hours a day?
Thanks for your help in advance

Vince