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joshua-t asked

Upgrading solar with an existing MPPT 100|50 charge controller

I currently have a solar system with 500W of solar (connected in parallel), a Victron MPPT 100|50 charge controller, and a Victron BMV-712 Smart Battery Monitor. For my batteries, I have three 125Ah Deep-cylcle, marine-grade AGM batteries connected in parallel for a total of 375Ah. All of this is installed in my off-grid tiny house.

I'd like to upgrade my solar to bring in more power. Just got a new job, and it requires a new desktop computer that uses a lot more power than my laptop. However, with my current system, I don't have much room for growth because I have everything set up for 12v, and the solar can bring in up to 40A (though it is typically closer to 30). I'd like to add some panels and re-arrange everything to connect them in series (or a combination of series and parallel) to bring the solar power up to 24v. However, I want to keep my batteries set up in parallel for a 12v system.

Can I connect my panels in series to create a 24v charge and lower the Amps, but use my existing MPPT to charge my batteries even if my batteries stay at 12v? Does the charge controller compensate, and do I have to change anything specific in the settings?

Thanks!

MPPT ControllersMPPT SmartSolarmppt charging
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trip-tracks answered ·

You can series up your panels up to 100V with the MPPT 100/50. The regulator will convert this to 12V to suit your batteries.

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launacorp answered ·

There are no 12V panels or 24V panels. This doesn't exist in "normal" applications.


Look at the Voc of your panels. This is typically around 22ish Volt at 25°C. The colder the panels the higher the voltage. I (personally) would calculate around 10% voltage on top for negative degrees. So the panel could rise up to 24.ish Volt for a "12V Panel". If you have a 100/50mppt you could bring up to 4 panels in series. The MPPT, as told by Trip-Tacks, converts it into 12V or if you wish 24V (for 24V System).

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joshua-t answered ·

Thanks! Is there a specific setting I need to change when I connect it, or will it detect it automatically?

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trip-tracks avatar image trip-tracks commented ·

The MPPT regulators will automatically detect the battery voltage when first turned on. You can check it/set it/change it using the VictronConnect software. You can also change a lot of other parameters including battery type using the same software. Analysis tools are also included as well as a neat 30 day history of harvesting. Very useful tool.

Buy the SmartSolar version and you can easily connect to it using Bluetooth, otherwise you will need a bluetooth dongle.

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misullivan avatar image misullivan trip-tracks commented ·

I thought that the MPPTs only detected the voltage and set themselves on *first* powerup... after that they need to be changed in veconfigure...

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