drafts:mppt_faq
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drafts:mppt_faq [2016-12-02 11:26] – [I want to over dimension the PV array, how can I calculate the maximum?] mvader | drafts:mppt_faq [2021-09-30 07:18] (current) – guystewart | ||
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====== MPPT FAQ ====== | ====== MPPT FAQ ====== | ||
- | ==== 75/15 and 100/15 cannot be controlled by a BMS, what now? ==== | + | ==== Q1: I want to size or oversize my PV array, how can I do this? ==== |
- | The reason is that the RX pin is already used to the battery life on/off selection with the jumper. So 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/ |
- | ==== Can the output of the MPPT be used as a power supply, thus without batteries? ==== | + | ==== 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:// | ||
+ | |||
+ | ==== 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. | ||
+ | |||
+ | ==== 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. | ||
- | ==== I want to over dimension | + | ==== Q5: 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. | ||
+ | |||
+ | Grounding is always done at one point only, to avoid ground currents. For a battery system, grounding must be done at the battery. | ||
- | 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 winter time. | + | ==== Q6: The Solar Charger |
- | How to determine how far you can over dimension | + | 1. Check that the PV voltage is high enough compared to the battery voltage. Either read it with a remote panel or VictronConnect. |
- | There are only two limits, when determining | + | Or measure |
- | - The Maximum PV open circuit voltage | + | 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. |
- | - The Maximum PV short circuit current | + | |
- | Both values are specified in the datasheets of all our MPPT Solar Chargers. The ratings of the array must not exceed these two maximum limits of the MPPT. | + | 3. Check that the battery voltage is set properly in the settings (12/24/48). |
- | The maximum PV power listed in the datasheet is **not** the maximum installable PV power. Instead it is the maximum charge current. | + | 4. Check for [[: |
- | **Long explanation: | + | If all above is fine, and still the unit does not operate, contact a dealer |
- | Note that you cannot multiply these values to determine the install-able maximum Wp. Instead, look on the datasheets of the solar panels, to see what their max PV short circuit current is. | + | ==== Q7: Can I use the MPPT Solar Charger as DC-DC charger? ==== |
- | And same for the Maximum PV open circuit voltage, and then do not forget | + | For example |
- | As an example, the maximum charge current of a 75/10 is 10 Ampere. When connected to a 24 Volt battery, it charges at 28.8 Volt. So the max charge power is 288 Watt. When installing a 300 Watt panel, it will reach its maximum charge current and power in summer. But not in winter. | + | No. |
- | To get less difference between summer and winter, you can install two panels, i.e. 600 Watt peak of PV. In summer | + | ==== Q8: Can I connect different |
+ | No. Under no circumstances. | ||
- | ===== DISQUS Comments ===== | + | ==== Q9: Can I use panels with optimisers? |
+ | No. | ||
+ | ===== DISQUS ===== | ||
~~DISQUS~~ | ~~DISQUS~~ | ||
drafts/mppt_faq.1480674361.txt.gz · Last modified: 2016-12-02 11:26 by mvader