General MPPT question.

[St8kout]

Is there a 'smart' MPPT controller that communicates with Inverters to adjust for load, instead of relying only on sensing battery voltage drop before going into Boost mode?
I find it annoying that my MPPT allows my battery bank to discharge even though it has more than enough power available to supply the Inverter and still recharge the battery bank, (during the day, that is).
If someone hasn't invented this by now, there's an obvious niche that needs filling. At the very least, maybe an 'amp sensor' you can attach to the Inverter input cable that reads amps just like the ones that already exists for hand held meters like electricians use.

[Sunking]

No need for such communication, it is automatically done via Ohm's Law.

When a Charge Controller completes its cycle of Bulk/Absorb, it reduces the voltage to FLOAT so it does not over charge the batteries. Assuming there is still daylight left, and the load does not exceed what the panels can produce, any load power comes from the panels, not the batteries. Otherwise if the load demands more than the panels can produce, the shortage has to come from the batteries. There is no other place to get the power.

As soon as the load demand decreases to what the panels can handle, then the panels will supply the power to the load, and any extra will go to the batteries to replace what was used. No communication is required or necessary.

Now if your controller is switching back to Re-Bulk just means you are using way more power than the panels can generate for a long enough time, the battery voltage will fall and cause the Controller to raise its voltage in order to recharge the batteries. But if the load demand still exceeds what the panels can produce, the voltage will stay low until the load demand ceases and the panels can catch up.

The controller already knows what the Inverter is doing, demanding more than the panels can generate, thus turns full on and try to catch up. The communication is the battery voltage, and the controller knows exactly what the voltage is. It does not need a gizmo to tell it what it already knows.

You cannot control where power flows. By the Law of Physics, energy balances out to ZERO every time.

[NEOH]

Is there a 'smart' MPPT controller that communicates with Inverters to adjust for load, instead of relying only on sensing battery voltage drop before going into Boost mode?
I find it annoying that my MPPT allows my battery bank to discharge even though it has more than enough power available to supply the Inverter and still recharge the battery bank, (during the day, that is).
If someone hasn't invented this by now, there's an obvious niche that needs filling. At the very least, maybe an 'amp sensor' you can attach to the Inverter input cable that reads amps just like the ones that already exists for hand held meters like electricians use.

Your MPPT Controller will not just let the battery bank discharge when the sun is shining, it will do its best to maintain voltage
You need to be more specific about your problem.
What is the model # of your Charge Controller ?
What voltage is your battery bank dropping to when the sun is shining?
What exactly is your Controller doing incorrectly?
You may have a Voltage Drop across the wires between your battery bank and your inverter, which is not an MPPT Controller problem.
Explain to us in detail what you see happening ...

[Mike90250]

Midnight Classic controller has a Mode called waste not where as the batteries fill up which could turn on extra loads to run a well pump to fill a cistern or an air compressor. use your imagination

[NEOH]

Midnight Classic controller has a Mode called waste not where as the batteries fill up which could turn on extra loads to run a well pump to fill a cistern or an air compressor. use your imagination

The OP is complaining that his battery bank is discharging during the daytime, when the MPPT should actually be charging the battery bank

[BackwoodsEE]

No need for such communication, it is automatically done via Ohm's Law.

When a Charge Controller completes its cycle of Bulk/Absorb, it reduces the voltage to FLOAT so it does not over charge the batteries. Assuming there is still daylight left, and the load does not exceed what the panels can produce, any load power comes from the panels, not the batteries. Otherwise if the load demands more than the panels can produce, the shortage has to come from the batteries. There is no other place to get the power.

As soon as the load demand decreases to what the panels can handle, then the panels will supply the power to the load, and any extra will go to the batteries to replace what was used. No communication is required or necessary.

Now if your controller is switching back to Re-Bulk just means you are using way more power than the panels can generate for a long enough time, the battery voltage will fall and cause the Controller to raise its voltage in order to recharge the batteries. But if the load demand still exceeds what the panels can produce, the voltage will stay low until the load demand ceases and the panels can catch up.

The controller already knows what the Inverter is doing, demanding more than the panels can generate, thus turns full on and try to catch up. The communication is the battery voltage, and the controller knows exactly what the voltage is. It does not need a gizmo to tell it what it already knows.

You cannot control where power flows. By the Law of Physics, energy balances out to ZERO every time.

This is exactly the right answer, and well said. There's really nothing more to it. I've spent way too much time watching my Morningstar TS-MPPT charge controllers (hey, it's free entertainment for a EE geek) and they supply what they can when a load comes online asking for more. No communication needed.

[sensij]

This is exactly the right answer, and well said. There's really nothing more to it. I've spent way too much time watching my Morningstar TS-MPPT charge controllers (hey, it's free entertainment for a EE geek) and they supply what they can when a load comes online asking for more. No communication needed.

It is the right answer for *your* controller, but probably not the OP's. Some controllers won't go back into a boost mode until voltage drops below a certain level. For example, the Renogy Rover has a "boost return" voltage setting. Once it gets to float, it will stay in a non-boosted PWM mode (current in = current out) even if load current exceeds charge current. Once the battery discharges down to 13.2 V (default setting), the mppt boost logic kicks back in.

I think the answer for the OP is "buy a better charge controller", or possibly, "Use the software interface to raise the boost return voltage level to a higher value." OP will need to respond with the actual charge controller model to be sure.

[Sunking]

The OP is complaining that his battery bank is discharging during the daytime, when the MPPT should actually be charging the battery bank

Not necessarily, not enough info to say. If the user daytime loads exceed what the panels can produce and be replaced, That is deficit charging. If that is the case says his panel wattage and battery capacity is too low.

During the day assuming the panels are correctly sized, his voltage should rise to around to 14.5 volts or so, then by before sunset should be Floating around 13.5 volts, and settle to 12.6 volts when the sun sets.

My guess at this point is the OP system is grossly undersized, Or his Controller went south,

[NEOH]

Not necessarily, not enough info to say. If the user daytime loads exceed what the panels can produce and be replaced, That is deficit charging. If that is the case says his panel wattage and battery capacity is too low.

During the day assuming the panels are correctly sized, his voltage should rise to around to 14.5 volts or so, then by before sunset should be Floating around 13.5 volts, and settle to 12.6 volts when the sun sets.

My guess at this point is the OP system is grossly undersized, Or his Controller went south,

Yes necessarily, that is the OP's complaint.

The OP states ...
even though it has more than enough power available to supply the Inverter and still recharge the battery bank, (during the day, that is).

[Sunking]

Yes necessarily, that is the OP's complaint.

The OP states ...
even though it has more than enough power available to supply the Inverter and still recharge the battery bank, (during the day, that is).

Sure about that? The OP does not seem to have a clue what is going on. The OP said:

I find it annoying that my MPPT allows my battery bank to discharge even though it has more than enough power available to supply the Inverter and still recharge the battery bank,

That is an oxymoron. A battery is either discharging or charging. It cannot do both at the same time. So which is it? Charging or discharging? .

[sensij]

Sure about that? The OP does not seem to have a clue what is going on. The OP said:



That is an oxymoron. A battery is either discharging or charging. It cannot do both at the same time. So which is it? Charging or discharging? .

The charge controller can be supplying part of the load while the battery is still discharging. The charge controller can be in float mode and not delivering the full capacity of the array until the battery discharges below the Boost Return setting, at which point the controller goes back into bulk and uses mppt to supply the entire load and begin charging the battery again. It sounds like the OP is objecting to the need for the battery to discharge before triggering bulk again, which, as I've already said, means the setting needs to be changed or a different controller used.