Victron MPPT solar charger
When powering up your Victron MPPT for the first time, best do that via the battery connectors using the system voltage with which you plan to operate it. This way the device will automatically recognize and remember whether it is supposed to run on 12, 24, or 48 volts.
A new device is allowed to be connected to PV first only if the system voltage is manually set correctly before connecting the battery.
Later it does not matter whether PV input or battery input is connected or disconnected first.
You may change the battery voltage any time in the device settings; the special case of 36 V needs to be configured manually this way.
Beware that the device may get damaged if connected to power having an entirely different voltage (e.g., 48 instead of 24).
Though it may be tempting, better not directly connect an inverter to the Victron MPPT load output. While being short-circuit proof, it may still get damaged by spikes on connect or disconnect. So connect an inverter only indirectly (via the battery connectors), where the Victron load output could be used to determine when to automatically switch off the connection on low battery.
Note: When connecting the MPPT input of a solar inverter (or any other form of DC-DC-converter) more or less directly to a battery,
even with a BMS and a circuit breaker (or some other form of fuse) in between that is supposed to limit the current,
its input capacitors cause a heavy inrush current for few milliseconds.
Depending on the battery, BMS, cable resistance, inverter model, etc., its peak within the first millisecond can be around 250 amps.
Also because a spark can be observed when connecting, many people believe that this is not safe and at least increases the risk of damage in the long run. Yet transient currents are not critical to capacitors, and also the internal input wiring of solar inverters is pretty solid, such that precautions regarding the inrush current are not really needed.
In case you still prefer to perform some kind of soft start, simple ways of doing so include:
- If the battery has a soft start capability, use that.
- When the PV input is connected during the day such that it has at least MPPT start-up voltage, connect to the Victron at first only the inverter in order to pre-charge its capacitors from the PV input. Then, after (at least) a few seconds, in addition connect the battery.
- Independent of the Victron MPPT and its PV and battery inputs, connect the inverter to the battery at first via a resistor having around 200 to 500 ohms that can handle at least 5 W power for pre-charging the capacitors. Then, after a few seconds per input line used, the resistor can be replaced or bridged using a sufficiently strong switch or circuit breaker, such that the full inverter input power may flow without loss.
For the serial VE.Direct data interface and its connection see Victron VE.Direct.
Note: It is better to buy a VICTRON MPPT SmartSolar instead of a BlueSolar as the former has integrated Bluetooth.
If you have a BlueSolar version, you may need to buy a VE.Direct Bluetooth Smart dongle in order to enter key setup parameters to the MPPT using your phone. You can disconnect the blutooth dongle after programming in order to connect the MPPT to the OpenDTU-OnBattery.
Alternatively, you can avoid all the above and use the pre programmed lifepo4 profile.
Note when configuring a Victron MPPT for the correct battery voltage:
-If you have a BlueSolar MPPT, just read the manual and set the physical dial
-If you have a SmartSolar MPPT, you can use the same physical dial on the MPPT to select the battery voltage, but that dial is ignored if the respective settings are made through the Bluetooth App. In that case connect to your Victron SmartSolar MPPT using Bluetooth and the respective App and check the settings.
schlimmchen commented last week
Im Bulk Zustand gibt die Batterie die Spannung vor, die den Strom "schluckt".
Der Laderegler wechselt von "Alles reinpumpen was geht" (Bulk) zu "Regle auf eine feste Spannung" (Absorption).
Im Absorption Zustand stellt sich der Strom von selbst ein, weil die Spannung fest ist.
Wenn der Strom dann klein geworden ist, geht es in den Zustand Floating. Dazu muss der Laderegler nichts über die Batterie wissen außer der Zielspannung.
You can (there are constraints) connect up to three Victron MPPTs with OpenDTU-OnBattery.
Keep in mind that you should also have the Victrons communicate among themselves!
If you have Smartsolar Victron MPPTs, it is very easy: Hier schließe Ich meine 3 Laderegler von Victron Parallel zusammen
Welcome to the 100€ question.
Let's do first some basics. You can connect solar panels between them either
- in serial order like
- in parallel order like
- in combination of both like
When this happens, each series of panels is called "a string"
Also, mixing different Panels is possible (causes power losses)
Important rule #1
Important rule #2
Ambient temperature impacts voltage. The lower the temperature, the higher the voltage and vice versa. Thus, a PV system that has been working fine during the summer months, may cause damage by over-voltage on a very cold (sub zero temperatures) sunny winter day!
People often ask whether they need separate Victron MPPTs if they install Solar Panels at different orientations.
In summary: You could but, you do not need to!
A quick (and dirty) explanation:
- Solar Panels connected in parallel to a single MPPT input are forced to have the same voltage
- Solar Panels have the same optimal voltage quickly, even if they hardly produce any power (Amps)
- Having East & West Panels together, both sides will very quickly achieve the same Voltage, one side will be delivering power (high Amps) whereas the other will have low power (low Amps)
- The Victron does not care (since the Voltage is the same on all panels) and will take the power from the panels that can deliver
- There will be inefficiencies early morning/late evening when the one side Panels will have so little sun that they can not even deliver sufficient voltage
- Despite the small inefficiencies, the savings on the extra Victron MPPT charger (and fuses etc. etc.) make such setups a good decision
As one Forum member writes:
Kann ich so bestätigen. Bei mir wären die beiden strings identisch mit identischen Modulen. In meinen Influxdaten gehen die quasi exakt zeitgleich an und aus und tagsüber sind die Spannungen wirklich nur minimal auseinander für wenige Minuten. Das rechtfertigt nie und nimmer einen zweiten Laderegler und die ganze Absicherung 2x finanziell, die paar % spielt man nie wieder rein.
The graph from the above member shows, the voltage difference between east (Osten) and west (Westen) is minimal, during the sun's full circle across the horizon. You will need to zoom in and look closely in order to see a difference (right-click with the mouse on the Graph and select "open image in a new tab"):
The picture below shows six solar panels of a test installation, spread in different positions and orientations.
The upper row is currently under the sun, while the lower row in completely in the shade.
You will notice that all panels have approx. the same voltage, although the lower row is not producing ( < 1 Amperes)
Another example: Two panels connected to the same MPPT. One almost fully in the shade, the other full under the sun. Both have the same voltage, and while the shaded panel deliver very little current (0.61 A), it does not block the other panel from produce much current (7.56 A)
For more information:
No disadvantages The tests on the two PV systems have shown that mismatching losses occur in an east/west aligned PV system with a common inverter for the east and west modules. As expected, however, these losses are very low and are partially compensated by the fact that the common inverter usually operates in a higher efficiency range. The minimal yield losses are offset by significant cost reductions in other areas: Firstly, the number of MPPTs and inverters can be reduced, and secondly, the nominal output of the common inverter can be reduced by up to 35% --- depending on the angle of inclination of the installed solar modules. In addition, installation costs can also be minimized.
Victron has developed a very good tool to help you ensure your selected configuration is within safety limits: https://www.victronenergy.com/mppt-calculator
For example, let us suppose these are the specs of your panels:
entering the key values into the MPPT Calulator and selecting max/min outside temperature as well as the combination of series/parallel panels as below:
Will result to this answer(s):
- At a temperature of -20 °C, your 3 series/2 parallel configuration will achieve max. 140 V (within the limit of a Victron MPPT 150).
- At a temperature of +65 °C (your panel temperature in summer) the same configuration will achieve max 88.2 V.
- The max. delivered current will be 35 A (due to the limit of an MPPT 150/35) and the power that could be delivered by your 3 series/2 parallel configuration will be up to 23% higher than the 35 A limit of the MPPT 150/35 (which is acceptable).
and this is the yield to expect
You can change the parameters yourself using the link to the above example: