AC300 with Dokio 220W Panels?

Product Discussion BLUETTI AC Series
1

Hello! I have the AC300 + 1 B300 battery.

I also have a Dokio 220w Suitcase style solar panel. Will these work together? I ask because, I connected them using an mc4 adapter and it did not work. The Dokio is 18v.

Here is the link to the panel: Amazon.com

Please note: TOTAL novice here: I do not speak solar :)

Thanks for any help.

2

Hello, theoretically it should work since AC300 AC input is rated 12-150 V but in real a 18 VoC panel like that, taking it for granted it could reach 18 V, must be in direct sunlight to provide a volt/ampere ratio which would be maybe enough to trigger the MPPT (internal solar charger).
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The AC300 battery side is nominally 48 V, so if yor DC input is less than 48 V, in your case 18 V, the internal charger would run in boost mode to increase the voltage above nominal to actually allow energy to flow in and charge the battery since a battery needs the input voltage to be higher than its voltage to be charged. This conversion process uses energy, so what you put in would need to exceed this threshold to provide a useful charge.
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In practice, the energy from your PV system should exceed what the AC300 needs (conversions, voltage drops due to connectors, efficiencies) to actually charge the battery, since what goes into the battery is the total energy you supply to the AC300 minus the energy the AC300 needs to do so.
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Said another way, imagine you have 2 identical bottles on a table, the first bottle has 48 liters of water, the second bottle has 18. If you connect these two bottles with a pipe in their bottom, and you want to move the water from the bottle with 18 liters into the full bottle with 48 liters, you need a pump, the pump consumes energy because it has to counteract the water from the bottle with 48 liters that wants to pass by gravity onto the bottle with 18 liters of water. This explains why charging a battery with a source that has a lower voltage than the nominal is very inefficient.
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If you tap the PV icon on the AC300 display homepage, what voltage do you read from the panels?

3

Thank you! That makes total sense. I do not have it connected currently, but will in 2 days, and plan to do some experimenting. I decided to buy a second panel just like the one I have, and connect the 2 in parallel. (I know series is recommended, but that is to not go over the volt max, correct?) Doing them in parallel would increase voltage to 36, no? I will come back with experiment results in a few days, and report the PV icon reading as well :-)

4

Please report back with your findings.
Make sure to connect them in series if you would like to increase the voltage.
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Imagine energy is a river where voltage is the speed of the river and current is its width.
If you parallel the two rivers you will result in a river with twice the width (current) but same speed (voltage).
If you series the two rivers you will result in a river with the same width (current) but double the speed (voltage).

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5

Okay, I’m confused. I thought Bluetti recommends only connecting in series in order to avoid overvoltage. Is that incorrect? More likely that I just don’t understand.
Also, are you a teacher? I’m a teacher, lol and I love your analogy. Thanks!

6

Just to be sure we understand series and parallel correctly with two panels A and B of 18V/12A each:

  • series is when you connect together A- and B+ and use A+ to PV input (+) and B- to PV input (-) → this way the voltage sum and current stays the same → nominal output will be 36V 12A
  • parallel is then you connect A+ and B+ together to the PV input (+) and then A- and B- together to the PV input (-) → this way voltage stays the same and current sum → nominal output will be 18V 24A

I’m not a teacher but I like to explain things in a way people understand. :slight_smile: