question

Hi Richard. You certainly could with a separate mppt cc paralleled into the same batts. The purists would say no into the same cc, and would usually be correct, but it *might* be possible.

You'll need to tell us pv specs, incl Voc and Vmp, how many, mppt type, batt V.

Yeh ok. One of the beauties of 48V is that you often find yourself with excess mppt capacity, and you certainly have that. Mixing in "18V" panels you wouldn't normally do, but if they come 'free' would be worth a try.

Your existing panels should be wired 3x series/2x parallel - check that! , with Vmp totalling 97.5V. You have to try to match that with each string of new panels. So (say) @ 18Vmp you could use 5x (giving 90Vmp) or 6x (giving 108Vmp). Neither is ideal, and there will be some loss apparent, but overall should still produce pretty well. You do have blue kit after all..

You can't break anything, unless of course you exceed 150Voc (less safety margin) on the mppt. *standard warning*.

Hope this helps a little. A tinkerer like I would have a go, help yourself.. :) Good luck too.

What is your Victron Bluesolar or Smartsolar regulator model there are currently three version type for PV input

100 , 150 and 250 Volt version, Max PV voltage units,

So its important that the OPEN circuit voltage does not exceed the PV voltage of the MPPT Regulator AT ANYTIME.

Now each string should have the same voltage or as close as possible, and within each string all the panels should have the same max current/amps, do not mix different amp/current panels within a string.

So there are a few important things to consider when mixing panels in series (excluding the consideration of partial shade effects.)

1. IMPORTANT all individual panels in the string should have the same amp/current output, plus or minus a few percent is ok otherwise you will reduce the output of the other panels or damage the lower amperage panels cells. do not mix different amp/current panels in a string.

2. IMPORTANT for the regulator, the open circuit string voltage must not exceed the max PV voltage of the MPPT regulator or you will destroy the regulator. Different voltage panels within the string are ok to be mixed. ie 36 volt and 18 volt panels (as long as each panels current output is the same)

3. If using multi strings in parallel then each strings voltage must be the same or quite close, keep in mind here that each string that's joined in parallel can output different amps/current higher or lower it does not matter as long as the total voltage is the same on all strings.

4. The Regulators max output wattage can be exceeded without issue as the Victron MPPT regulators will only allow the max wattage of the regulator through at any one time and thus just clip the excess amps/current off without damage. (NOTE do not exceed max voltage)