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.
How to Cash a Check. So, you've got a check that you've received as compensation for work, for a birthday gift, or for another given reason. You're ready to cash that check and to put that money to good use, and you step out of the house to do it...only to realize that you have no idea what the heck to do with it.