Reddit reviews Victron BlueSolar 75/15 MPPT Charge Controller - 15 Amps / 75 Volts

You need to stay within the amperage limitations of your wiring and charge controller.

For instance, this is a good charge controller that can do 75v and 15 amps, so in theory you would think it could do 1125 watts. But that's not the way it works. You need to keep peak voltage and amperage under 100/15, and load voltage and amperage will be a good bit less.

You could run three 300w panels like this in parallel with a charge controller that can handle 40v 30 amps, or you could run the same panels in series with a charge controller that can handle 120v 10 amps. The wiring needs to handle the amperage, so much smaller wiring would be needed for the latter.

If you did more, smaller panels, like six 150w panels, you could do a series/parallel combination for something like 80v at 15-20 amps. That would go very nicely with this charge controller.

And then there's the decision of how likely you are to want to expand the system and if you should buy equipment that can handle more panels.

Create a short list of your preferred charge controllers and their capacities, then start shopping for panels and do the quick math. If the panels were the same dollar-per-watt I would probably do six 150w in series/parallel with the controller I mentioned above. If you think it's likely you may expand capacity, I would go with three 300w panels in parallel with this controller, then you could add 6 more of the same (2700w total) in series/parallel without changing your charge controller or wiring.

I really like the new Victrons. Blazing fast mppt. And you can add bluetooth monitoring/programming. Which is really nice.
v75/15

Controller https://www.amazon.com/gp/product/B00U3MK0CI/ref=oh_aui_detailpage_o08_s00?ie=UTF8&psc=1

Panel https://www.amazon.com/gp/product/B06XVWPD7N/ref=oh_aui_detailpage_o09_s00?ie=UTF8&psc=1

Just found that these Victron MPPT solar charge controllers have a lithium charge profile you can select: https://www.amazon.com/dp/B00U3MK0CI/ref=cm_sw_r_tw_awdo_x_ClVtybFR6JJ4Y

Still wondering if there is some elegant way to tie in alternator charging

true looks like almost a $120 difference.. damn

PWM

vs.

MPPT

edit: any thoughts on this one? sounds pretty great for a 200W setup.

Are you within the Amazon return window? Send it back.

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That is almost certainly not a real MPPT charge controller, and it is way overpriced for what it is. The "PV Off" setting is where charging stops and the battery goes into float. A single setting is not enough, with this controller you will always undercharge and eventually ruin the battery prematurely.

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A proper charge controller (MPPT or PWM) allows you to set a level for Bulk charge (i.e. approximately 80% charged), Absorption charge (the remaining 20% to full) and Float charge (trickle charge once full).

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If you are on a budget, on the cheaper side get Epever or Renogy. This 30A Epever is a proper MPPT controller and is more than enough charge controller for your setup (with a 30Amp MPPT you can go up to ~400W of solar if you are charging a 12V batttery system).

https://www.amazon.com/EPever-Controller-Tracer3210AN-Charging-Regulator/dp/B07BHKJSFN/ref=sr_1_8?keywords=epever+tracer+40a&qid=1562524137&s=gateway&sr=8-8

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With a 100W panel you don't need a 40Amp controller, or even a 30Amp controller. A 100 watt, 12V nominal panel (i.e. 18-20V PV) will produce around 5.5 amps, and a real MPPT controller might raise that to 7 amps charge to the batteries. This 15A Victron controller is vastly superior and can handle up to 200 watt solar when charging 12V batteries.

https://www.amazon.com/Victron-BlueSolar-MPPT-Charge-Controller/dp/B00U3MK0CI/ref=sr_1_4?keywords=victron+75%2F15&qid=1562524536&s=gateway&sr=8-4