Trust me, if you work on solar energy systems, you need at least one of these. If you affix mc4 connectors in the field, you need two. The side prongs will effortlessly squeeze the locking tabs on a connector without damage (though you appear to need a different tool for the evil Amphenol ones), and the odd shaped hole will stop the connector from turning as you use the spanner end to tighten the weatherproof packing at the bottom. Yay.
An engineer came into the office today who will remain nameless mainly because I forgot his name. He told me of hijinks at the Dayton Hamvention in which he rigged a portapotty’s seat with conductive tape, a dc flourescent lamp driver, and a small solar panel on top of the ‘loo. When sunlight hit the panel, the seat became… Well, the least pleasant portapotty seat ever.