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Can the CCGX activate relay for hot water heater when excess solar available after battery charging duties?

CCGX Color Control
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Thankyou. I thought the generator output could be used. Cheers

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Paul B avatar image
Paul B answered ·

you could program the relay to close when the battery voltage raises to a set figure or SOC plus a heap of other options

the relay has a few different modes available.

one as a example is generator autostart, now I know you are not interested in autostart per say,but as a example you could use this to turn the relay on /off ,and thus the relay could close a contactor that turned the hot water heater on or off.

it also has a quite hours operation that allows you to control the time of operation.

so have a look at that area and see if that maybe of help


hope the above makes sense


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Pat Davitt answered ·

I am working on a project to address the issue of calculating and using "Excess Solar Power" to run an electrical load. The question is; "What is Excess Solar Power?" You can't calculate it unless you know the current Solar Irradiance at the array and the temperature of the solar panels themselves. Using information from a CCGX and a solar irradiance/temperature sensor from Mencke & Tegtmeyer GmbH in Germany it is possible.

This functionality requires a few non-Victron components (A PLC or Raspberry Pi). The components arrive on Monday and I plan on starting another thread to discuss this project.

Pat

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Very interesting - I would love to know more about this.

can you link the thread when its up please?

Sounds cool.


People inside Victron are also thinking about how to solve this same problem.

In an off grid system, I am considering using earlier staggered frequency relays to bring in loads, before throttling the PV inverters.

Alistair Warburton avatar image
Alistair Warburton answered ·

I plan to implement this using a PLC, only because I am comfortable with PLC.s and they are solid, not because you coudnt do it with anything else.

RE the accepted answer...

I get the complexity surrounding potential solar charge but I would suggest it largely dosnt matter.

If the load, lets call it a dump load, a water eater perhaps, is basic and simple, just on/off then modulating it will only require a simple duty cycle with a very low frequency, perhaps even in minutes rather than seconds. A variable load is even easier.

The trigger would be SOC and a charging current.

If SOC is >= xx% and there is charge current, run the load at some duty cycle.

Duty cycle would be a function of charge current, at the battery, which will be floating.

Within the top few % of SOC terminal voltage will drive the solar charger so adding a load will reduce terminal voltage causing the solar charger to ramp up, assuming it can.

Essentally you would be applying load untill the float foltage started to fall, slightly, at which point the solar is supplying all it can, maintaining the dump load and battery float voltage.

Now I apriciate that waiting for absorbe to finish or float to start, whichever will be required but as I havent looked at detail yet, I havent commented.

My point is that exess solar can be defined in terms of what it can do as opposed to what is theoretically available. MPPT does exactly this, making a change observing the result and then either making another change in the same direction or resetting the change it just made.

Sure you cant determine what is available if the charger is throttling the very thing you are trying to measure but you can draw some load and determine if the charger is keeping pace with it.

Al

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Pat Davitt avatar image
Pat Davitt answered ·

Have created a new post for the project. It can be found here:

https://community.victronenergy.com/questions/7170/calculating-and-controlling-excess-pv-power.html

Pat

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Boekel answered ·

Difficult to give advice without knowing the system.


When you have Lead-acid batteries, you'd want them to finish charging. when you have Lithium, I'd just start the load at a certain battery voltage.

If you use a Multi / Quattro (with AC2 output relay) you can also program this so that when there is more current draw on the system, the AC2 output is shut off.
You can also use the Venus for this, just need an extra relay to switch AC currents.

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