I've started using these around the house for both 120V and low voltage DC wiring and they're super easy and secure. Here's a pretty comprehensive video on the topic with respect to RVs.
I'll be using them on my RV projects from now on. They're especially convenient for tapping into an existing circuit. They're the same type of connectors found in the terminal blocks of many electrical components like surge suppressors, etc.
This is what I bought as a starter pack:
I forgot to mention that they work on both solid and stranded wire.