Add additional panels : Should I upgrade my MPPT or add another ?

[starmage]

I have 6x355 panels and a Victron BlueSolar 150/45 MPPT (max 2600w input from panels). 

Although my summer production is basically enough most days(basically +- 13kW production), my winter production is almost half that at arounf 7.5kW.

I now want to add an additional 6 panels to specifically increase my winter production.

 What is best :

1. add another 150/45 MPPT 

or

2. Replace the current MPPT with a larger model e.g. 150/70 (max 4000w) 

 

[wolfandy]

51 minutes ago, starmage said:

1. add another 150/45 MPPT 

or

2. Replace the current MPPT with a larger model e.g. 150/70 (max 4000w) 

Adding a 2nd MPPT would give you the option to have the new panels face a different direction (e.g. capturing the early morning sun)

If you replace your current MPPT, I would go for a 250/XX model. This allows you to connect more panels in series, which result in a longer solar day

Maybe play around a bit with the PVWatts Calculator and see which direction will give you the best yields?

[starmage]

Forgot too add - its a flat IBR roof, so there is only 1 direction  (direction and pitch is excellend for summer >85% efficientcy, where as in winter the efficiency drops to about 60%)

[wolfandy]

9 minutes ago, starmage said:

so there is only 1 direction 

In that case I would upgrade to a 250/XX model and re-wire to put more panels in series. Are you currently running 2S3P? If yes, you could then add your new panels to make 4S3P - which means you would not even need to pull any new wires or add any new combination boxes (obviously assuming that your current wires/boxes can handle the new config)