Question regarding my VOC readings

[smpeters20]

I've recently purchased 4 Helios 275 watt solar panels. My plan is to run a 48 volt system. 2 panels will be in series and both sets of 2 panels will lead into a combiner box down to my charge controller. Their specs read a VOC of 38 volts. I made the BIG mistake by not initially checking these panels with a volt meter upon arrival. Instead I mounted the panels and put in series 2 panels for 1 set and 2 panels for the other set and wired down to my charge controller. Before hooking into the charge controller, I took a reading on my 4 gauge wire of the positive and negative leads and found that I was only producing 36-38 volts when I should be getting close to 72-76 volts. This was on a clear, sunny day. I decided to measure each panel directly to see the VOC measurement, so I disconnected everything. My readings are: Set 1- Panels 1 & 2 read 36 volts and 0.9 volts. Set 2- Panels 2 & 3 read 12 volts & 24 volts. These readings are not nearly close to what I should be getting. What baffles me is why these panels that I disconnected from a series connection and measuring individually are adding up to around 36-37 volts which is what I should be getting for each panel individually. I hope I made this scenario clear. Does anyone have a clue what could be happening or have happened?
Thank you for your help.

 

[Gavin A]

sounds like you were shading the panels so that the bypass diodes were operating on panels 3 and 4, not sure about the 2nd panel but are you sure you actually had a connection on the multimeter prongs?

Alternatively you have some very duff panels.