This video tutorial will show you the optimal way to make generators.
The absolute most efficient and best power output comes from three intersecting lines of power blocks, one line on each axis (X, Y, Z). The longer the lines, more power you get from a single block. For example, the 5x5 arrangement above has 76 power block and produces 9520 e/sec. The same 76 blocks in a straight line produces over 31,000 e/sec. To put it simply, make a single line of power that extends as far as your ship is long, wide, and high, and you'll always be better off than putting in generators.