Building a solar panel and need to run the pipe in parallel...

Use two 90 degree fittings with a 1 inch section of 1/2" pipe sweated in is the best way I know how to do it. If you bend it any sharper than that it will kink the tubing and leak or restrict flow. Flexible 1/2" tubing is available but and it will not form a 180 degree turn of a smaller radius than what I described. If you need other than stright sections the flexible tubing uses standard copper fittings.

Thanks for the advise... want to do it right!

In addition to previous advice: if you look for tight turn, use 90 and street 90...

However, if you don't care how tight the turn is than I would suggest that you use Bending Tool and create that 180 degree turn using Soft Copper. That way you will eliminate sharp turns and at least 4 soldered joints. Also, water will flow better through that turn with less friction and less noise.

All good solutions but why go to the hassle of building one out of fittings or bending soft copper when you can purchase a return bend already made, (see image)?