fourtytwo
New Member
Hi all I have my own inverter design and a while ago I added periodic (~ every 10mins) voltage sweep to it so the MPPT could be kicked off of subsidiary peaks caused by shading, this indeed has worked very well.
Now I have added a secondary array of panels on a Pergola roof to get a little more altitude and enable true south facing rather then the SSE of the existing ground mount. The idea was to cover more of the day especially afternoons in winter.
I could not get any more of the original 265W panels so the new array is totally different being 2*435W panels, consequentially the array voltages do not match at all. As an experiment I decided to simply parallel them (with a diode on the lower voltage array to protect it against reverse current) and let the MPPT/sweep system sort it out.
As can be seen from the enclosed screenshot of the logger this works very well with the sweep finding the higher output of the two arrays and pointing MPPT at it.
I find on cloudy days such as today the new panels generate nearly twice as much power as the old, in the particular example plot ~600W vs ~300W. The angles and orientation are old SSE/72 degrees, new S/13 degrees.
I will see how this progresses, There might be enough space on the pergola to accommodate another 430W panel or I could add a fixed voltage boost to enable better parallel operation of the two arrays together although the inverter is limited to ~1200W.
In case you are wondering why I don't have a large roof array like seemingly many on here the answer is I have no suitable southish facing roof at all sadly, wrong house from that pov!
Now I have added a secondary array of panels on a Pergola roof to get a little more altitude and enable true south facing rather then the SSE of the existing ground mount. The idea was to cover more of the day especially afternoons in winter.
I could not get any more of the original 265W panels so the new array is totally different being 2*435W panels, consequentially the array voltages do not match at all. As an experiment I decided to simply parallel them (with a diode on the lower voltage array to protect it against reverse current) and let the MPPT/sweep system sort it out.
As can be seen from the enclosed screenshot of the logger this works very well with the sweep finding the higher output of the two arrays and pointing MPPT at it.
I find on cloudy days such as today the new panels generate nearly twice as much power as the old, in the particular example plot ~600W vs ~300W. The angles and orientation are old SSE/72 degrees, new S/13 degrees.
I will see how this progresses, There might be enough space on the pergola to accommodate another 430W panel or I could add a fixed voltage boost to enable better parallel operation of the two arrays together although the inverter is limited to ~1200W.
In case you are wondering why I don't have a large roof array like seemingly many on here the answer is I have no suitable southish facing roof at all sadly, wrong house from that pov!
