DIY: Do It Yourself Solar Panels is the cheapest way to go.

You can buy the Solar Panels and use wiring to a Charge Controller that charges batteries (DC 12v-24v), which you can use an Inverter to send 120volt AC power to your appliances, etc

The easiest way to assemble the Charge Controller, Batteries and Inverter is with an All-In-One Power Unit. The best expandable Combined All-In-One Power Unit for the home is the AC300+B300 expansion battery. (3072WH for $2,999, expandable with up to 4 expansion Batteries + 2400Watt Solar Input)

Watch a Review of the AC300:

Less expensive, but less expandable and more portable for an RV is the AC200Max (2048WH for $1499, expandable with up to 2 expansion batteries + 900Watt Solar Input).

Watch a review of the AC200Max by MinuteManPrep below:

Solar Panels on your house should cost about $1/Watt.
I suggest 2 x 550Watt Solar Panels from Renogy or SunGold for just over $1,000.

Portable Solar Panels cost 2-3 times more, but you can take them anywhere. 300W from 4 foldable Solar Panels = $799.

OK for 24 hours would for a fridge and some lighting, the AC200Max (2048WH for $1499, expandable with up to 2 expansion batteries + 900Watt Solar Input).

If you have more appliances to run, like Air Conditioning, Ovens and Computers, or want to power basics for more that 24 hours (e.g. a Blackout), better is the AC300+B300 expansion battery. (3072WH for $2,999, expandable with up to 4 expansion Batteries + 2400Watt Solar Input)