VOC MPPT Voltage

VOC = Volt open circuits
MPPT = maximum power point tracker

The VOC is with every solar cell (or ever positive impedance source) is always higher then the working voltage.

With Solar cells VOC is usually Specified with a cold Cell at 1000W/m² illumination and and 0A (so also 0W) Drawn.
so non realistic conditions.

So the Real world Output of 12VOC solar cell will always be lower then 12V.
The Maximum power Point will be at depending on temperature and Illumination at around 9V

Q6: What kind of solar panels should I choose for EB3A?

EB3A is compatible with solar panels with 12-28V Open Circuit Voltage,

So Thats wrong.
EB3A needs around ~13V to start Charging all and >14V the MPPT to start working.
At and below 12V the EB3A not charging and a 12VOC solar panel will always be below 12V

Hi @lambda

I think this question from the FAQ is only meant for choosing a Solar Panel that doesnt kill the MPPT or choose a Solar panel which delivers enough voltage to get the EB3A starting and reconize a solar panel



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I think this is something that can be resolved with a capacitator on the solar cable as described here: EB3A Solar input not working - #13 by sgreenshot

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the capacitor can increase the “burst” current but not the voltage.

The Capacitor is only a ugly fix for a bad MPPT algorithm implementation.

“An ugly fix” that works !!! And it helps me a lot to extend my daily range for charging.
I get more than 4 hours charging time

The Capacitor helps to solve an problem that should not be there in the first place.

But it can’t help to make a lower Voltage work if the problem is not a current limit.

Any official Update on this?


The manual say OCV /VOC but the VOC point is by definition at 0W power.
In operation the panel is per definition always below VOC.

How can it work with solar cells <12V if it needs >12V to start?

Cold conditions will often cause the VOC to exceed the rating. I believe those rating are done in mild weather, around 60 F & with a panel that has warmed up some from the sun.

Before any voltage resistance is realized the VOC can damage a mppt.