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kai-fuchs avatar image
kai-fuchs asked

Redirect Solar DC when Battery is full to other use

Hello

I want to use the power of my solar to do other things after my battery’s are charged.

This has been asked in several ways. But let’s make it more general.

Setup:

200W Solar

Mppt smartSolar 75/15

Smart shunt

160Ah AGM battery

I have this setup deployed in several offgrit applications (vans, Garden, etc), the main purpose is to charge the battery’s to store energy for later use. But 80% of the time my battery’s are full and the system just idles. This is wasted potential, therefore I would like to automatically redirect the power from the panels. Let’s stay my smart shut is telling me I’m charged 100% I want to redirect the DC from the panel to another use, and recharge the battery’s if they drop below 90%. I would need to redirect between mppt and Panels to power eg. a solar pump that fills my water tank or let my van act like a small scale balcony power plant.

I understand the smart shunt can not trigger a relay. Just using the Load out put of the Mppt, triggered by battery voltage thresholds, would also drain my battery’s creating unnecessary changes cycles.


Is there any way I can use the information that smart shunt is giving me to redirect where I want to put the energy Im potentially producing?

If no, how can I pull this off?

Edit:

- One way would be to enable the SmartSolar face decisions based on VE.Smart network information. (like it does with a low temperature charge cutoff)



Thanks in advance

Kai

MPPT SmartSolarSmartShuntoffgridVE.Smart Network
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Michelle Konzack avatar image Michelle Konzack commented ·
You can program the Relais Output to be activated e.G.


1) High Voltage

2) if Battery is on Float

3) if Battery is in Absorbtion

...

I do this with my 200l Boiler, which require around 12,5kWh to increase the temperature from 10°C (well water) to 60°C. In the summer my Batteries (currently 70,5kWh SOPzS but I am waiting for the Upgrage to 175kWh) are 85-90% full in the Morning hence my 6kWp Solarpanels are tough enough to charge my batteries in until 10:00 and then heat up the 200l boiler.


Oh, I get around 45kWh a day from my Solarpanels, hence impossible to use it up... but needed in Spring and Autum!


The only thing which is basicly missing is an EV... ;-)

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hardy-tuner avatar image
hardy-tuner answered ·

Your mppt can Switch something at load Output, but is maybe not smart enough for your wishes without a cerbo (or raspberry) Venus OS

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kai-fuchs avatar image kai-fuchs commented ·
Thank you for the answer!


I believe the Mppt should be smart enough, due to the fact that it’s performing a similar operation with the low temperature cut off.

Installing multiple Cerbos would cost quite a lot for a little improvement. And ideally this could be solved by improving software rather than adding hardware.

I’m might try the option with a cerbo for experimenting purposes but not to Rolle it out to all systems.

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kai-fuchs avatar image
kai-fuchs answered ·

Hey Michelle,

Thank you for your answer!

I'm not sure if you are referring to the relais in the Cerbo or an Smart MPPT. I'll go down tomorrow first thing in the morning to check again if the MPPT allows the switch on load when battery is in float. This would be new to me but would solve the problem.

Regards Kai

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Michelle Konzack avatar image Michelle Konzack commented ·
I simply use the Relais from the SmartSolar. The solar charger has everything available you need to do this.


The Cerbo GX is only needed, if you want to do something more complex.


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kai-fuchs avatar image
kai-fuchs answered ·

Hey Michelle, the mppt only allows turning load on or off based off voltage not based of “float” status.

The problem is as soon as I redirect my panels to power the solar pump (relais between panel and mppt) I'll loose the float voltage and therefore the panels would be switched back to the mppt. The solar pump runs off 30-120V directly connect to a panel. Therefore I can not just power it through the load of my 24v system.

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Michelle Konzack avatar image Michelle Konzack commented ·
Ahhh, this is a different case.


Why do you want to disconnect the Solarpanels from the MPPT?


MAYBE you can try following:


Connect the Relais contact and pump parallel to the MPPT and THEN switch the Relais using the Relais output of the MPPT.


If you now setup the MPPT to switch on the Relais on "float" it should work.

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kai-fuchs avatar image kai-fuchs Michelle Konzack commented ·
This is my plan, the only issue is to switch on load on „Float“ my Mppt is not supporting this option.
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Michelle Konzack avatar image Michelle Konzack kai-fuchs commented ·
Which one do you have?


I have several SmartSolar and ALL have in the menu for the Relais the option FLOAT.


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kai-fuchs avatar image kai-fuchs Michelle Konzack commented ·

Hey Michelle, i got the a SmartSolar MPPT 75/15 and a BlueSolar 75/10. Both don´t show that option. Anyways I just bought a Cerbo but even with the "Standard" relais options I´m not able to do so. the Relais option are quite limited, eg. the Generator start stop is the only feature that allows a relais action based of SOC but the start SOC needs to be bigger that the stop SOC. Looks like i need to learn how to program something myself.

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derrick thomas avatar image derrick thomas kai-fuchs commented ·
You should be able to accomplish something fairly easily with node red.
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kevgermany avatar image
kevgermany answered ·

Probably better to do this from the battery side of the system, not the PV side. If you switch on the panel side of the MPPT, every time the MPPT sees the panels, a new charge cycle will start and it will think it's a new day.

The load output of the MPPT is intended for this, but depending on MPPT model, may provide limited power. You will need to keep load below a level that causes a large voltage drop while the load is applied. Suggest you check the manual for your MPPTs and see if the load configuration will work for you.


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