question

lorettaboy avatar image
lorettaboy asked

Trying to decide between Victron 100/30 or 150/35 MPPT

Okay, i'm designing a solar system for my 30 foot travel trailer and would appreciate some advice. I'll have 6 100 watt mono solar panels on the roof, paired in series then wired in parallel. My battery setup is 2 6volt Trojan T105's. This setup will be used for boondocking; running the trailer lights, water pump, fan, and light use of a smart TV via a small inverter. Nothing crazy. Based on this setup, what MPPT would you recommend between the 100/30 and the 150/35? Specs for the solar panels are:

  • Maximum Power: 100W
  • Open Circuit Voltage (Voc): 21.6V
  • Max Power Voltage (Vpm): 17.3V
  • Short Circuit Current (Isc): 6.17A
  • Working Current (Iop): 5.78A

Thanks in advance!

MPPT SmartSolar
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5 Answers
seb71 avatar image
seb71 answered ·

Get the 150/35.

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ddickov avatar image
ddickov answered ·

Hi there I would always go for the highest rated mppt for your system incase of future expansion.

Wired in series would give you multiplied voltage per connection 6 panels open circuit pairs if I’m right on this should be 43.2 volts for two panels, three pairs then wired in parallel would equal 43.2volts input and a current level two panels in series doubles the voltage and halves the current so would equal one panel current level of 6.17a for your two panels.

The first number incase you aren’t aware is the input voltage max and the 30/35 is the charge current.

I would double check also the battery max charge current would be the second number on the mppt. If you upgraded your battery bank for example or expanded it would maybe require a higher charge current than the smaller mppt’s can supply. I would always if it’s affordable get a slightly higher rated unit.

I have the mppt 150/70TR and it’s flawless and it’s slightly oversized but does the job as always.

Victron have also in the phone app got an mppt calculator tool. This would ensure you selected the correct product for your system.

Hope this helps a bit thanks david

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marc-de-montreal avatar image
marc-de-montreal answered ·

hi,

what is your serie/parallel configuration? (for the max voltage).. 6 x 100w on 12v = 50amp.. you should use a 60 amp mppt but at this level of charge, your batteries (6v x 2) will gaz if charging more than 1/3C.. i suggest you to limit the charge at 1/5C (20amp for a 100ah batt) with a 30amp mppt setted at 20amp maximum.. maybe someone have a better idea..

Marc

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Vance Mitchell avatar image
Vance Mitchell answered ·

Neither.

As marc-de-montreal stated, 600w is 50A into 12v. (When charging @ 14.4v, 40A is more realistic)

I believe the T105 are 225Ah each and have a recommended max charge rat of around 30-35A.

For around the same money as the 150/35 you could purchase the 100/50.

This would then allow you to set your charge rate down if you wanted but would also allow you to fully utilize your panels if you ever upgrade your battery bank.

It would also allow you to add more panels in the future if you decide to upgrade (subject to finding the same panels or compatible). (limited upgrade available depending on location).

For that system your wiring seems ok with three parallel pairs of panels.

Personally I would consider going to two parallel sets of three in series to reduce wiring requirements and simplify the connections.

The best advice would be for you to visit or phone your nearest dealer and discuss your requirements with them and they can ensure that you get the most appropriate setup for your circumstances.


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seb71 avatar image seb71 commented ·

When installed horizontally, the panels will be less likely to ever produce at their rated power.

On the other hand, during unfavorable conditions, slightly oversizing the panel array is desirable. You need the most you can get during cloudy days.


I already explained how to wire them (and told about other panel options) here.

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alan avatar image
alan answered ·

If you went a 150/45, you could wire all 6 panels in series.
Having a higher string voltage is much more effective in overcast weather, plus the 150V will allow a wider configuration window if you decide to get better panels later. Like some 250w standard grid panels.

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