With the small LED 20x15 matrix I noticed significant power loss when using the easy connectors for the LED strips.  I didn't see this problem when I soldered the LED strips, it's a pain but seems like worth the effort.  I used a 5v 20amp power supply with the 20x15 matrix.  With the large LED matrix each LED strip will have a 180 LEDs (8.2 ft).  I am not planning on running all the LEDs while at full power.  White at full power each LED draws up to 60mA.  I did some testing and this seemed very accurate.  I also needed to know how my power supply would handle over current conditions.  I shorted out the 5v side and was happy to see that the cheap chinesse power supply had over current protection (not that I want to exercise this).  

I will have a total of 150x14=2100 LEDs  ( I'm using 300 LED strips).  

   150LEDs x .06mA = 9A  again this is not a condition I will be running.  But I need to know the worst case.  This is also at the brightest level.  I am planning on running it at 150 (highest 255) and avoiding lighting all LEDs at White.

I have decided on using two 5v 60AMP power supplies.  

https://www.ebay.com/itm/5V-12V-24V-48V-Power-Supply-Driver-AC110-220V-TO-DC-Switch-adapter-For-LED-Strip/372130850519?var=&hash=item56a4ba26d7&enc=AQADAAADAFjVrDbVsZ8oH%2F8PNHtt9VX4%2Fw7FZcmMuqsX8uaFEduVSz4vIe%2FNsHnySsSb2Y%2Fh06UBzvwT7x0q8j8223IVcmn9k6O6ojzxe4je7mWSKfxBPHayb5V0vxzw1ZO3tH7ySO%2BRlquKKulIr9PsFBmykHmBEdEZvP%2BQjsS96kGRmf0jLqqiwJ7EQPSsy58HaK5nV4F5CTb7iINV9DRtdS23GjdcJCc8z7yO9ygOQ31FAvfzth26%2FZpaWxFoqR6flCSW1bBh9%2F8YngTTqft%2Bun44qhaONK6NB3UavjefCPRjBkB4Rj5DXMVBLfVSwebtreJTB7EjYtcKdy52GvWhsieW0KDRnz0UZ1TSSHSm3nspmnZDt%2B2hwBN%2BEfX7npL9tIUkuusplMqdc1klLacNDTERFzevFGiW5gmdp60h4baS%2BaBjAtJMcu2ZkP%2F2cTgyz6ZTFbu5%2B0MuKXVtBWJ%2Bic3CigPxMnkvTX%2FgoC%2F9a4PnCGwEiyOEHxLggZSKWUaNilPhFz4BfoXwHWs1EoJxkwc5o9AlWY9%2BKlooLfX7PRvx0C2poDUTTgLkoQBWgEQXrcchgx%2BktT7Q%2BScQUuYboBe1tEi%2F%2BPqi9b3z21gPcWQxplLkZHEU7m70Tho%2B3dZW%2B5y8d51HpYp7tFD%2Fxdu05h8jUfLwYas9pK%2BHIdBY6MFEHcadrV%2FxF7coVLMHuIxizw56RG40RQXX3Jvtc3L8RXCkopWYHqZtQGufDKBs1v2A5o8vPZIYfk7ePhaLQ3EeKpDxcOrx0v92rQ4MZpVXV550S2...

One area I am concerned about is the the environment that the power supplies will be running in.  The barn does not have AC and gets hot and very humid in Maryland.  I am planning on mounting mounting a fan to help cool the power supplies.  At this point I'm leaning towards a 120v fan instead of a 5v fan, mainly because I need this system to work for year after year, and I think the 120v will be more reliable in the long term.