Inverters and "direct" consumption

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karistote
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Inverters and "direct" consumption




by karistote » 28/09/17, 05:18

Hello everyone,

Here is my case: I have (potentially) 1000 Wp of PV to install
(400 already installed in test for now)
PV are 12v / 100W mono. (connected in series of 24v)

I also have a wind turbine that can output 600W Max, also in 24v.

In my case, I want to use as much power as possible
at the time it is produced, I have relatively little need
storage (very low consumption at night for example).
In addition, I would like to limit the size of the battery park required.
I don't care if there are losses (energy produced but unused)
I could for example divert these towards a resistance of water heater.
(which will greatly limit the losses in question)

The question is therefore the following: which inverter (s) me
would you advise for this use? (Maximum direct consumption)
Knowing that, I do not refuse to add a few Wc eventually.

For now, and as an example, I have a victron mppt 100/50 charger
on 240 Ah of 24V batteries. I also have a German inverter of 3000W in 24V
I have a problem: when the victron goes into "absorption" mode, the voltage
delivered to the batteries is then about 29V, which turns the inverter into safety
(for over-voltage at input).

Thank you for your analyzes, and advice :)
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karistote
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Re: Inverters and "direct" consumption




by karistote » 28/09/17, 05:52

Well, I’ve already fixed a problem, I can adjust the absorption voltage on the victron :)

On the other hand, the question of a regulator with a DIRECT output (I have already seen some in PWM)
always arises ... Do you think I can without fear "hit the batteries" in full
charge cycle with the current config?
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izentrop
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Re: Inverters and "direct" consumption




by izentrop » 29/09/17, 01:02

Normally no problem, the maximum power of the panel is lower than that which the regulator can support.
It is just necessary to avoid the deep discharge of the battery, in case the sunshine is insufficient to compensate for the discharge.

In principle, the inverter disconnects use as soon as the battery voltage drops to around 22 V. This is normally provided for in its specifications.
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Re: Inverters and "direct" consumption




by ENERC » 04/10/17, 09:44

For now, and as an example, I have a victron mppt 100/50 charger
on 240 Ah of batteries in 24V

It's good, you will not exceed 20% of the battery: 1000 (W) / 24 (V) / 240 (Ah) -> 17%

Well, I’ve already fixed a problem, I can adjust the absorption voltage on the victron

Do not go too far below 29V, otherwise the batteries will die quickly.

In absorption mode, the battery makes bubbles (hydrogen and oxygen) which mix the acid. During charging / discharging, the concentrated acid goes down while the less concentrated acid goes up. The purpose of absorption is to mix this acid.
If you do not mix enough, the battery loses its capacity and sulfate.

If you are too annoyed you can put a large diode to drop by 0,7 V the voltage seen by the inverter.

Do you think I can safely "hit the batteries" right in
charge cycle with the current config

Yes No problem. Ideally, let the Victron finish its absorption which it automatically calculates according to the charges / discharges. The best thing is that the Green led (Float) lights up at least a few minutes a day.
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