Matthew C avatar image
Matthew C asked

Problem with Victron MPPT in parallel with wind controller

We have the following 48V Victron setup:

  • Multiplus II
  • 150/35 MPPT
  • CCGX
  • 48V, 260Ah SLA array

As an experiment we are trying to add some wind power to keep the batteries topped up at night and in bad weather etc. The wind controller unit is setup to have a higher cutoff than the Victron and during testing we are putting about 4-5A into the battery array. The unit is simply wired in parallel with the DC bus.

The Victron MPPT seems to behave as expected as it approached the set-point (current backs off to less than 1A) until it switches to float mode.

What appears to happen when the Victron switches to float is that it gets confused by the other charging source and switches back to bulk charge mode. This is then dumping the full 35A into the battery and taking the bus voltage up to ~55V, until we pull the plug to stop it.

So we are wondering if there is something in the MPPT configuration options that would enable us to stop the Victron from behaving like this

Hydro and Wind Power
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Can you do a screen recording of the Trends screen in VictronConnect of the battery voltage and battery current when this occurs?

Have you tried setting the wind controller to slightly lower target voltage than the Victron MPPT?

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48v-on-56north avatar image
48v-on-56north answered ·

2nding Guy's comments.

I have circa 4KW 12 panels across two Victron Smart MPPT's They are linked for charge control (with feedback from Pylontech BMS). The Victron/Pylontech loop controls High Voltage Discharge to just over 52V. Solar takes it to 90-97% SOC.

In parallel, a 3KW Winturbine where the (tristar)MPPT HVD s set just below 52V. This way the Windturbine is 'bulk charging' but stops before the Victron solar MMPTs. Wind will take the battery to 80-85% SOC, then stop.

Key is to prevent the Turbine taking SOC above 85-90% where most damage can be done to the battery bank either by too high current or by confusing the Solar MPPT's. Its helpful if the windturbine turbine MPPT battery voltage sense is directly on the battery terminals to avoid HV Disconnects in gusts.

HVR (high voltage reconnect) happens battery when battery voltage has dropped 1-2V to 50-51V which is equal to loosing 15-20% SOC. Hence without sun and with amble wind the batteries will cycle between 65/70 and 85/90 % SOC which is a safe operating zone for LiFePo.

You may consider some way of braking / load dumping, when the HVD occurs. I switch over the turbine to a set of dump load resistors that moves the turbine out of the power zone and its left turning slowly until the In my case a 5KW 1 ohm resistor across the turbine hence able to absorb 50-60V 50-60A which is quite a lot of braking but its acting smoothly to slow down the turbine.

In a fully operational system like an off grid house, there is plenty of ways to use excess energy so load dumping or braking should be rare.

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icavanaugh avatar image
icavanaugh answered ·

It is never wise to integrate non-managed charge sources since equipment can brake, create over voltages/current and destroy your system that way. Especially in off-grid systems when you really depend on the energy you generate and store.

I have a completely different approach on integrating wind turbines to the Victron with ESS, using enPhase IQ8M micro-inverters on AC-Out, a super capacitor banks to store energy and a SmartSolar 250/100 to ensure the voltage specifications on the micro inverters are not exceeded.

Basic concept is the have the AC from the wind turbine (with a short-circuit stop switch before rectifying) rectified to DC and insert directly into the PV connection of the SmartSolar 250/100. The SmartSolar already wakes up of 5V generated from the turbine and start to charge the capacitor banks. The micro inverters are connected in parallel to the battery connection on the Smart Solar. In parallel to the micro-inverters a super capacitor back of 64V 14.5F to store energy to stabilize the voltage drops to the micro-inverters. You can add as many banks as you want to temporarily store more energy then 260Wh in my case.

The micro-inverters have a start voltage of 22V and a voltage range of 16V to 45V. To never exceed the maximum voltage of the micro-inverted configure the SmartSolar for a 36V battery bank.

This way every voltage which is generated by the wind turbine is temporarily stored in the Super Capacitor Bank(s) as long the turbine generates more than the voltage in the capacitor banks. The micro-inverter will start inverting at already 22V. It will keep inverting until 16V is reached. If the wind keeps the voltage generated by the turbine above 16V it keeps inverting and delivers the power to my Multiplus-II 3 phase ESS on each AC-Out respecting the 1:1 factor. This energy then can be used to either charge the batteries (by the Multiplus-II charger which is managed to my 48V, 30KWh Pylontech array) or delivered to the grid using ESS assistant without interfering with a Victron installed system and disrupt measurements.

I am still testing with this setup but the first results are very promising and production of a small vertical turbine is significantly more then connecting it directly to my 48V DC bus. The big difference here is to reach 48V you need powerful winds, to reach 22V a small breeze is enough ;)

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usernamepasswordbs avatar image usernamepasswordbs commented ·
@icavanaugh Sounds complex but very interesting.

Please keep us posted.

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