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.
When a weather service issues a forecast calling for rain, it is usually followed by a probability. For example: P.O.P. 60%.. This expression means there is a 60% chance that any random place in the forecast area, such as your home, will receive measurable rainfall. Measurable rainfall means at least 0.2 mm of rain or the water equivalent of snow.