Mixing solar panels?

[chiefk]

Right now I have 2 144 watt amorphous panels connected in series feeding my Morningstar 45A MPPT controller with about 80 volts. I would like to add a 200 watt panel to this setup. I am unsure of how to connect it. Say a 24v system panel of 200 watts. Do I hook it up in parallel with my setup or what?

[inetdog]

Right now I have 2 144 watt amorphous panels connected in series feeding my Morningstar 45A MPPT controller with about 80 volts. I would like to add a 200 watt panel to this setup. I am unsure of how to connect it. Say a 24v system panel of 200 watts. Do I hook it up in parallel with my setup or what?

You need one of three things:

1. If you can match the output voltage within 5%, connect the new panel (string) in parallel.
2. If you can match the output current within 5% and the total voltage is not too high for the controller, connect the new panels in series.
3. If you are too far from either condition, you need a second controller with its own MPPT input.

[chiefk]

You need one of three things:

1. If you can match the output voltage within 5%, connect the new panel (string) in parallel.
2. If you can match the output current within 5% and the total voltage is not too high for the controller, connect the new panels in series.
3. If you are too far from either condition, you need a second controller with its own MPPT input.

Makes sense to me, thanks for the advice.

[inetdog]

Makes sense to me, thanks for the advice.

You are welcome.
Under some circumstances greater mismatches may be tolerable (like where one of the panel groups is much lower wattage than the other, or you are adding one higher current panel in series to an existing lower current string), but that sort of thing requires individual calculation rather than rules of thumb.