I have an AC500 that has a solar input limit of 150 Volts. Can I have an array of panels that exceeds 150V and use a device that would not allow the input to exceed 150V? In other words, is there a device that can be set at 150V that will keep the solar input from going over 150V?
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Same problem here, trying to add more solar panels without going over the 150V limit, as you can’t lower the panel Voc.
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I did see some 405 watt commercial sized panels with a Voc of 37V, where 4 in series would equal 148 Voc, and at 1620 theoretical watts, that might just be the way to get 1500 watts one side of the ac500 inputs. They are pretty big, so there would be trucking costs added on. They are one of the few high wattage panels I see with a Voc below 40Volts. I find myself shopping by Voc instead of wattage.
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You should consider running your solar panels in a series-parallel configuration. I personally have a ac200max. Which has a 145 volt & 15 amp limit. I was running 5X 200 watt panels in series, the panels have a 28.1 OCV @ 8.55 amps. I was not regularly hitting the 920 Watt limit, more of a 750 watt max under continuous hot sun.
So i wanted to add more solar, in order to add a 6th panel and stay under the 145V limit, I wired them in 2 strings of 3. Each string is wired in series, the 2 strings are wired in parallel. I could add up to 2 more of these panels per string (10 panels, 2000 watt total). Making for a large over paneling while staying safely within spec. My amperage is a little over spec but that isn’t a safety issue, just less ultimate potential, which my 920 watt cap supersedes anyways. I suspect your amp limit is higher anyways.
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There have been numerous posts on exceeding the solar voltage input limit and they state that it will damage your unit. I would rather not take a chance and even approach the limit.
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There is a PV step down voltage module listed in the accessory portion of the Bluetti site that reduces incoming voltage to 120 volts.
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Thanks for your recommendations. I also search for Voc first. Is it a problem going over the 1500 wattage limit of the AC500?
Thank you. I will check it out.
Yes, I have considered that wiring configuration and over- paneling. The AC500 has the Amperage limit at 15A. Thanks for your response.
I am going to try a few 150v zener diodes to limit the voltage. This is for another device that has 160v max input but wanted to share the idea for you guys.
30Pcs SR5150 Schottky Rectifier Diode 5A 150V MBR5150 SB5150 Bypass Blocking Solar Doorbell Diodes 5 Amp 150 Volt Axial Switching Zener Dioden DO-27 Package https://www.amazon.com/dp/B0CKSQNGST?psc=1&ref_=cm_sw_r_apin_ct_346MZ8PWHZ2A5X3XG7ZN&language=en_US
Don’t risk to go near the voltage limit if you are living in cold environments.
The voltage increases when the temperature decreases.
My PV strings VoC is 136,5V at 25° C and increases to 149,9V at -3° C.
Any colder than that will surpass the voltage limit.
Victron has a MPPT sizing calculator for this:
https://www.victronenergy.com/mppt-calculator
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Theoretically yes, but make sure you research the topics sufficiently for your own safety.
My take - Concerns with Using Zener Diodes for Voltage Limiting:
Power Dissipation: Zener diodes are generally used for voltage regulation in low power applications. When used to clamp high voltages at significant currents, such as those in solar panel setups, they can dissipate a lot of heat. In your case, if the voltage needs to be clamped at 150V and the current involved is up to 15A (as with the AC500’s maximum), the power dissipated by the Zener diode could be very high, potentially leading to overheating unless properly managed with heat sinks or cooling systems.
Voltage Stability: Zener diodes are not typically used for high power applications because they may not provide a stable voltage under varying load conditions. In a solar power setup, load variations are common, which could lead to voltage spikes exceeding the Zener diode’s clamping voltage.
Reliability and Safety: Implementing Zener diodes for high voltage and current applications can be risky. Any failure in the diode could lead to an over-voltage situation, potentially damaging the connected equipment or creating a fire hazard.
Another approach would be the D300S drop-down module of Bluetti. It regulates any voltage up to 450V to 120V. Sounds ideal on paper, but the following illustrates the potential dangers of DYi’ing your own Zener solution.
I’ve had a relevant experience with the D300S drop-down module when I used the AC500 as a backup generator after my main system malfunctioned. My rooftop setup includes 6 strings at 225V, which exceeds the AC500’s capacity. Initially, the D300S was effective, but unexpectedly, it failed and allowed the full 225V through. Thankfully, the AC500’s built-in protections kicked in promptly, preventing any damage by blocking the input.
This incident serves as a crucial reminder of the potential failures in voltage regulation devices, even those professionally manufactured. While the D300S is designed to reduce voltage to safer levels, its failure mode allowed a dangerous voltage pass-through, a design flaw where ideally, it should have disconnected the load.
Given this, I urge caution, especially when considering a DIY approach like using a Zener diode-based voltage clamping system. Even with substantial electrical expertise, the risks of unexpected equipment behavior and the consequences of failure warrant careful consideration. It’s important to implement redundant safety measures and regularly test all components to ensure they function correctly under all conditions.
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I completely agree with DECERTO’s answer.
In such a configuration, if the battery is fully charged, then the Zener will conduct all the panel current : the Zener diode would need to be rated at the same power as your panels. This means a very large and expensive Zener and a big heatsink.
In my opinion, even if it requires more work, it is better to resize the configuration of the solar panels to have an intrinsically safe installation with the batteries.
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I forgot to say that the Amazon link given above points to a rectifier diode and not a zener diode when I look at the datasheet. The ad on Amazon is poorly written and shows the word “Zener” but I think it’s not a Zener diode.
Good catch. I totally missed reverse breakdown of the zener rated in mA. That wont work at all!