Mixing Panels

[kittysmitty]

My system is 12 volt with 2 100 watt panels. I looking at adding 3 135 watt panels. They would be in parallel feeding a single controller. Any issues? Downside? Thanks

[DamonHD]

If their Mpp is similar, then fine, though I would put in blocking diodes to stop any of the panels being backdriven by the others, especially if they have different orientation or shading.

Rgds

Damon

[kittysmitty]

Currently the two 100 watt panels are pole mounted. The new three 135 watt will be roof mounted, so blocking diodes might be necessary. Would you use separate diodes for each panel, or one for the pole panels and one for the roof panels? Thanks

[DamonHD]

You might as well do them separately; it's probably as easy and may well cost the same, and gives you some additional resilience and comfort if something unexpected happens (like a gull dumping on one panel)!

Rgds

Damon

[dnix71]

I have ground mounted panels pointing 3 directions to compensate for shading and variable clouds/weather. Two controllers are used and are maxed out for wattage. Controllers have embedded diodes on the output so I don't need to add any. I do have schottky diodes on some panels to prevent losses from shading. My panels are series in pairs for higher voltage which also gives better charging during shading/overcast weather.

I would love to roof mount, but that would mean codes and inspections and I would also have to own the place.