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samuil avatar image
samuil asked

How to keep load on during the day and switch off at night time - MPPT

Hi,

I would like to have my MPPT 75/15 to operate as normal during the day, but cut power to the load at night.


I like the concept of the street light function however it appears to only do the opposite.

I have searched other options on the forum which have pointed towards the user defined algorithms in the load output operation mode section.


I read that it has 'load switch high voltage level' and 'load switch low voltage level.' I want the load to completely turn off, not just reduce in power. Maybe it does cut off power completely and I am just interpreting it incorrectly.


If you could please let me achieve my scenario that would be great.

Kind regards,

Samuil

MPPT Controllers
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4 Answers
David avatar image
David answered ·

You would think that could be an option, wouldn't you?

Adding some non-Victron kit into the picture, you could run the load output though a little 30A relay (cost just a few pennies) and have that relay switch on/off using the PV input into the controller, so when the sun goes in at night and the panel voltage drops, the rekay switches off and the load is disconnected.

Depending on the relay, you may need to reduce the PV voltage into the control line via a regualator, but the currents required are so small, only basic devices would be needed, not high wattage ones.

(this is the approach I would take anyway for that requirement).

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samuil avatar image samuil commented ·
Hi Thanks for your response.


I see, so there is no way to actually have the MPPT charge my battery during the day & give power to my load? Then at night have it switch of the load to not waste any power?

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wkirby avatar image
wkirby answered ·

How about using the streetlight function with inverse off - on settings?
I have not tried this myself, but it might work for your application.

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David avatar image David commented ·
now THAT makes sense :) never looked at the Streetlight menu before :D
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mtadao avatar image mtadao David commented ·
I have such a setup driving a water pump during the day. Will post the settings shortly.
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mtadao avatar image mtadao mtadao commented ·

This works for me during the day. Use always on, or set the algorithms to use in load output settings. Street light setting must be off and your load output will work




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samuil avatar image samuil mtadao commented ·

Could you please show me screenshots of your settings please, I’m still a bit new to this and don’t want anything to go wrong.

I’m just a little confused, why would the street light option be turned off? My goal is to have the load turn on by itself once the sun rises and turn off once the sun sets, so if we remove the streetlight setting and not use the settings by wkirby how does it know to turn on and off ? :/

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samuil avatar image samuil commented ·
I will give it a go tomorrow during the day and let you know!


Cheers

Sam

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samuil avatar image samuil commented ·

Hi I have put these settings in:


Do I have to wait 3 days for the charge controller to synchronize as it hasn’t turned on yet?


For the load output does it make a difference if I set the setting to battery life instead of always on?

Cheers

Sam
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samuil avatar image samuil samuil commented ·

Hi @WKirby , sorry to bother you again. Our system didn't turn on with the above settings and it's been 1 full day cycle (sun/night). Do I need to wait 3 days for the charge controller to synchronize as it hasn’t turned on yet?


Could you please check my settings above and see what I am doing wrong?


Cheers

Sam

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mtadao avatar image
mtadao answered ·

This works for me. I have set those voltages so that the load does not over consume from the 24volts battery system

Screenshot_20210729-214159.jpgScreenshot_20210729-214217.jpg


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samuil avatar image samuil commented ·
Hi,


Thanks for your contribution.


I use a 12v battery, what voltage would I need to set for my build? I see your vales are not exactly 24v.


How does your system work on days with no sun light, will it turn off?

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mtadao avatar image mtadao samuil commented ·

It depends on how much solar power you get and how much power your load is and how low you want your battery to go, hence the voltage settings. You can also have power always on regardless of the battery voltage. The settings can only be by trial and error for your system until you get the right low n high voltage, but don't set 12volts as your minimum as you will find yourself with a flat battery! Try a minimum of 12.3 as a start and when the charger sees less for 2 min, it disconnects power to the load.

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samuil avatar image samuil mtadao commented ·
Thanks for this, I don't think we can rely on this method, I will try the above method mentioned by kirby. But greatly appreciate your input!


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henriv avatar image
henriv answered ·

I know it's a late reply..

Acording to the manual , "Switch on before sunrise" still switches off at sunrise. That is why the setting did not work for you.

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