It can be particularly good when paired with a crawdad + another pet. He can cast sunlight to increase health and healing, toss a HoT on himself, and move to the back row while other pets do stuff using Sunlight's increased health and healing to their advantage. That said, this is the basis of many types of stall teams, which tend to have a negative view by the community.
Solar Beam can be used as a finisher if you time it as the kill shot on the last pet you are facing. You cannot swap while recuperating from Solar Beam however.
Carry Pet Experience Reference Guide: