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drafts:mppt_faq [2017-09-06 08:44] – [MPPT FAQ] mvaderdrafts:mppt_faq [2021-09-30 07:18] (current) guystewart
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 ====== MPPT FAQ ====== ====== MPPT FAQ ======
  
-See also [[victronconnect:mppt-solarchargers|]]. +==== Q1: I want to size or oversize my PV arrayhow can I do this? ====
-==== Q1: 75/15 and 100/15 cannot be controlled by a BMSwhat now? ====+
  
-The reason is that the RX pin is already used to the battery life on/off selection with the jumperSo therefore it is unfortunately not possible to control these two models with the VE.Direct .. remote on/off cable [link]. The solutions is buy the next model in line: the MPPT 100/30.+See the blogpost [[https://www.victronenergy.com/blog/2014/03/28/matching-victron-energy-solar-modules-to-the-new-mppt-charge-regulators| Matching solar modules to MPPT charge controllers]].
  
-==== Q2: My MPPT is only showing voltage readings, not currents and also no Watts? ====+==== Q2: 75/10, 75/15 and 100/15 cannot be controlled by a BMS, what now? ==== 
 + 
 +By default the RX pin is already used to control the battery life on/off selection with the jumper. Use VictronConnect to change the function of the RX pin to remote on/off to enable BMS control. See 
 +[[https://www.victronenergy.com/media/pg/Manual_SmartSolar_MPPT_100-30__100-50/en/configuration-and-settings.html#UUID-b6cabb55-8d14-4fc9-190f-c0856aab60d3]] for details. 
 + 
 +==== Q3: My MPPT is only showing voltage readings, not currents and also no Watts? ====
 Make sure to *not* connect PV minus to the battery. See the manual. Make sure to *not* connect PV minus to the battery. See the manual.
  
-==== Q3: Can the output of the MPPT be used as a power supply, thus without batteries? ====+==== Q4: Can the output of the MPPT be used as a power supply, thus without batteries? ====
  
 The answer is; it depends on the type of load. The answer is; it depends on the type of load.
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 Loads where under voltage does not apply, like light globes, can be operated without any problems. Loads where under voltage does not apply, like light globes, can be operated without any problems.
  
-==== Q4I want to over dimension the PV array, how can I calculate the maximum? ==== +==== Q5: What about grounding one of the PV array poles? ====
- +
-Over-dimensioning a PV array is installing more Watt-peak than the maximum charge power of the chosen MPPT charge controller. A common reason to over dimension is to cater for winter time.  +
- +
-How to determine how far you can over dimension the PV array? +
- +
-There are two limits, when determining the maximum array size that can be connected to an MPPT: +
- +
-  - The Maximum PV open circuit voltage (Voc at STC) +
-  - The Maximum PV short circuit current (Isc at STC) +
- +
-Both values are specified in the datasheets of all our MPPT Solar Chargers. Those two ratings of the PV array must not exceed these MPPT limits. +
- +
-Note that these two maximum ratings must **not** be multiplied to determine the maximum installable Watt-peak. Instead, each of them needs to checked by itself: +
- +
-=== Determining the maximum PV open circuit voltage === +
-First look on the datasheets of the solar panels to see what their maximum open circuit voltage is. Then multiply that by the number of panels that are in series in the array. The result of the multiplication must not be higher than the Maximum PV open circuit voltage as listed on the MPPT Datasheet. Make sure to not forget taking the coldest expected temperature into account. Because the colder it is, the higher the open circuit voltage on a PV array will be. +
- +
-=== Determining the maximum PV short circuit current === +
-Get the maximum PV short circuit current from the PV Panel datasheet. Multiply by the number of panels in parallel in the array. Having more panels in series does not change the number. +
- +
-The result of the calculation may not exceed the Max PV short circuit current as specified on the MPPT Datasheet. +
- +
-=== What about grounding one of the PV array poles? ===+
  
 The MPPT is non isolated, meaning that the minus of the PV input is at the same potential as the minus of the battery output. The MPPT is non isolated, meaning that the minus of the PV input is at the same potential as the minus of the battery output.
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 Grounding is always done at one point only, to avoid ground currents. For a battery system, grounding must be done at the battery. Grounding is always done at one point only, to avoid ground currents. For a battery system, grounding must be done at the battery.
  
-==== Q5: Solar Charger is not charging ====+==== Q6The Solar Charger is not working ====
  
-1. Check that the PV voltage is high enough compared to the battery voltage. Either read it with a remote panel or VictronConnect. Or measureon the terminals on the charger!, not elsewhere and mind fuseswith a Volt meter.+1. Check that the PV voltage is high enough compared to the battery voltage. Either read it with a remote panel or VictronConnect. 
 + 
 +Or measure the voltage with a Volt meter. Make sure to measure the voltage on the terminals on the charger. Not elsewhere, to rule out any faulty wires or fuses. The panel voltage needs to be at least 5V above the battery voltage for the charger to start power conversion; [[https://www.victronenergy.com/support-and-downloads/manuals|see the manual for more information]].
  
 2. For models with a Remote on/off switch (a green two pole connector, labelled Remote L H), check that the jumper is in. L and H need to be shorted for the unit to switch on. Only the large models have this connector, see datasheet for details. 2. For models with a Remote on/off switch (a green two pole connector, labelled Remote L H), check that the jumper is in. L and H need to be shorted for the unit to switch on. Only the large models have this connector, see datasheet for details.
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 If all above is fine, and still the unit does not operate, contact a dealer to have the unit tested. If all above is fine, and still the unit does not operate, contact a dealer to have the unit tested.
 +==== Q7: Can I use the MPPT Solar Charger as DC-DC charger? ====
  
-==== Q6: Can I use the MPPT Solar Charger as DC-DC charger====+For example to charge a 12 Volt battery from a 24V battery bank?
  
-For example to charge a 12 Volt battery from a 24V battery bank?+No. 
 + 
 +==== Q8: Can I connect different panels to the same charge controller==== 
 + 
 +No. Under no circumstances.
  
-Yes. +==== Q9: Can I use panels with optimisers? ====
-===== DISQUS Comments =====+
  
 +No.
 +===== DISQUS =====
 ~~DISQUS~~ ~~DISQUS~~
  
drafts/mppt_faq.1504680264.txt.gz · Last modified: 2017-09-06 08:44 by mvader

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