question

Lyndsay Cotton avatar image

How does the MPPT work if panels are placed on North, East and West facing planes

Hi everyone. I'm onto the next install and need to understand the actual functioning specifically of the Smartsolar charge controller xxx|yy - TR and the xxx|yy- MC4.

1. Why (Is the) difference between the TR and the MC4.

My supplier told me it's "safer" to use the TR than the MC4 option as there is less chance of a poor connection / they have seen failures on the MC4 due to high currents.

I would like an opinion on this.

This also then leads to the next question

2. Can one charge controller be used on multiple planes. I believe I do understand the concept of MPPT's. I am unsure of how the Victon Smartsolar xxx|yy - z deals with this

2a. Is there a difference between the MC4 and the TR other than actual connection / termination.

2b Would an MCT option be able to manage 3 different inputs eg one each of a North, East and West facing PV arrays.?

OR;

2c. Irrespective of the termination configuration, I would need a SEPARATE charge controller for each plane?

Should I not understand the concept I would value assistance.

Lastly,

3. My West and East facing arrays are smaller than the North facing array. Am I correct in understanding that I would be able to install smaller Smartsolar charge controllers for those 2 arrays.(Naturally taking into account for string voltages and Isc)


I will be installing 2 x 48|5000 Multiplus ||'s

Many thanks






MPPT - Solar Charge Controllermppt charging
2 |3000 characters needed characters left characters exceeded

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

2 Answers
Kevin Windrem avatar image
Kevin Windrem answered ·

I believe all the MC4 connectors on those MPPT models are connected in parallel. They are not separate inputs so handled by one MPPT algorithm.

2 comments Share
2 |3000 characters needed characters left characters exceeded

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

Thankyou - This answers a nagging question.

Would this answer possibly be different on other brand CHARGERS. (Not hybrid Inverters)

seb71 avatar image seb71 Lyndsay Cotton ·

The new "RS" solar chargers from Victron have multiple PV inputs (2 or 4). But these are solar chargers for high voltage strings - many panels in series (which you might want or not).

seb71 avatar image
seb71 answered ·

Tr version has "clamp-down " style connector wires for PV.

MC4 version has MC4 connectors (like the PV panels conectors) for PV input.


Battery connectors are the same on both (and the same as on Tr version).

In my opinion your installer suggested the better option (Tr).

-------

All PV panels (modules) connected to a certain MPPT charger should face the same direction (same azimuth) and should have the same inclination.


Only one exception is allowed (but not recommended): you can connect to a single MPPT two identical PV arrays, one facing exactly East and the other facing exactly West (on a roof with two sides, facing E and W).


------

MPPT chargers (connected to the same battery) for different PV arrays can be different sizes (even different brands, but then you lose some nice features).

3 comments Share
2 |3000 characters needed characters left characters exceeded

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

Thankyou for the answers

Yip, I concur - do not mix brands

@Seb71 I have done some research and with assistance of a previous tutor, I reference an article written by Dipl-Ing.(FH) Dietmar Staudacher, Fronius International GMBH.

In his paper he concludes that mismatching of one MPPT on an East/West Scenario vs a separate MPPT for each East and West is so nominal that the cost saving of only one MPPT far outweighs the losses experienced.

Basic installation rules would apply:

a. Shading must be avoided

b. The number of modules must be identical in all strings

c. Within a single strin, the inclination andgle and orientation of the solar modules must be identical

seb71 avatar image seb71 Lyndsay Cotton ·

I read that study.

But:

  • sometimes you have shading during certain times of the day (it might not be your case);
  • the two sides of the house roof in most cases are not facing exactly E and W;
  • if you use two MPPTs, these can be smaller, so cheaper - it's not twice as much;
  • redudancy might matter for some;
  • the less strings in parallel connected to a certain MPPT, the better.