Individual solar cells are somewhat difficult to solder to. Self-adhesive metal stained-glass tape makes for the easiest soldering job--the tape holds itself in place while you solder. Use electronics solder that contains 2% silver. One side of the cell is (+), the other (-).
rain check (plural rain checks) (idiomatic) Any voucher or note from a merchant to a customer to provide an item the merchant has run out of at a later date for the item's current price, or (in a more literal sense) to provide a service at a later date.
4 [intransitive, transitive] when rain pours down or when itâs pouring (with) rain, rain is falling heavily pour (down) The rain continued to pour down. It's pouring outside. (British English) pour with rain It's pouring with rain.