PH18

abdallah.91

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Hello all,

please I need your help, I am new in the solar energy world :), i installed last weel 12 panels 405W each, the configuration is 4 groups of 3 series panels. so each each group is <140v VOC under the PH18 5045 PLUS MPPT limit which os 145V. my problem is that I mostly need the system during the day more than over the night in Lebanon when there is an electricity crisis. the idea that Untill I import batteries I am uusing 4 old cosumed battery (distinct model, size,..) so I am using them just to make the inverter launch because it requires batteries, my needed power is 2000W. my face problem is that even if the sky is totally clear, the sun is pure if I load the inverter around 1800W it starts consuming from the batteries continuously (I waited 3 min and that values almost the same) around 1100 watts. is it logic for a solar system 5Kw inverter and panels during sunny days to take from batteries to feed 1.8 Kw charge instead of the solar panels charges the batteries and feeds the home appliances?
 

syclonedriver

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I would expect your panels to to support 1800 watts if the sun was strong and high in the sky. Are the panels facing the sun? What brand of panels? Remember shading kills output. Try isolating each group of panels, maybe have a bad panel or connection.
 

abdallah.91

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I would expect your panels to to support 1800 watts if the sun was strong and high in the sky. Are the panels facing the sun? What brand of panels? Remember shading kills output. Try isolating each group of panels, maybe have a bad panel or connection.
yes the sky is perfect, sun is obvious and nothing shades the panels all the day. the direction is almost optimal, 35 degrees vertical and directed to the south. this is the best orientation in Lebanon.
depending to the panels, they are TrinaSolar, Monochristalline, 405w, 51V Voc, 10,2A short circuit current.
please note that I didn't use PV combiner so I used a cable junction as the attached image describes.
4 mm DC cable with 50 m lenght is enough?
 

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abdallah.91

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I isolated all groups then I connected each one alone and measure the voltage just before the inverter, all were ok with voltage around 136V. could the 4 mm DC cable limit the current or it is excluded because there is no drop in voltage?
 

Horsefly

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I don't know what a PH18 5045 is, and neither does Google. You also didn't say what voltage your system is (12/24/48). Your nameplate 12 x 405W says your PV array should be capable of 4860W under STC. However, your charge controller is rated for a certain maximum current, and that is all you will ever get out of it. If you have a 24V battery, the MPPT would have to be rated at over 200A, or 100A for a 48V system. To generate 1800W on an 85% efficient inverter, you would need 1800 / 24 /.85 = 88A (for a 24V system) or 44A (for a 48V system).

Bottom line: You need to tell us about your system voltage, charge controller specs, and inverter specs.
 

abdallah.91

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I don't know what a PH18 5045 is, and neither does Google. You also didn't say what voltage your system is (12/24/48). Your nameplate 12 x 405W says your PV array should be capable of 4860W under STC. However, your charge controller is rated for a certain maximum current, and that is all you will ever get out of it. If you have a 24V battery, the MPPT would have to be rated at over 200A, or 100A for a 48V system. To generate 1800W on an 85% efficient inverter, you would need 1800 / 24 /.85 = 88A (for a 24V system) or 44A (for a 48V system).

Bottom line: You need to tell us about your system voltage, charge controller specs, and inverter specs.
sorry I miss typed the Must inverter model, it is PH18-5048 so 5Kw 48V.
I mentioned the configuration in the first thread, "the configuration is 4 groups of 3 pv in serie".
thanks for your attention.
 

Horsefly

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sorry I miss typed the Must inverter model, it is PH18-5048 so 5Kw 48V.
I mentioned the configuration in the first thread, "the configuration is 4 groups of 3 pv in serie".
thanks for your attention.
OK, that correction helps. I found the PH18-5048 on Alibaba, looks as though the PV input voltage is limited to 130V, according to this sheet, not the 145V you said in your first post:
PH18-5048.JPG

You said you had 4 parallel strings of 3 PV panels in series, and you said the Voc of the panels is 51V. 3 x 51V = 153V, so you are way over the limit on this PH18-5048, not even taking temperature into account. On most solar charge controllers, exceeding the voltage limit on input will fry it. If you have not yet fried it, I would fix your PV array to be 6 parallel strings of 2 panels in series.

The maximum amps out of the charger is 80A which should be more than enough to get your 1800W, but we don't know what the box is doing since you probably went over-voltage on the PV input. Your total watts of PV (4860W) exceeds the rated power of the P18-5048 (4000W), but that might not be a problem.
 

abdallah.91

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thanks @Horsefly for you attention,

I just checked again the PH18-5048 PLUS datasheet from Must company itself, please see attached a screenshot of its specifications table, the max pv serie open circuit voltage is 145V, and I checked in sunny day clear sky the voltage of each panel, no one exceeded 46v, so at max the 3 panels serie gave 137V. and that is the value which I read on the inverter display at very sunny times.
 

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Horsefly

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thanks @Horsefly for you attention,

I just checked again the PH18-5048 PLUS datasheet from Must company itself, please see attached a screenshot of its specifications table, the max pv serie open circuit voltage is 145V, and I checked in sunny day clear sky the voltage of each panel, no one exceeded 46v, so at max the 3 panels serie gave 137V. and that is the value which I read on the inverter display at very sunny times.
You have to use the open circuit voltage (Voc from the panels). The document you are showing even says that. The highest voltage you will see is not doing the sunniest part of the day. It is when the sun first starts to hit the panels but there is no current flowing yet. When there is current flowing the voltage will drop down from Voc. That's why your Vmp is lower than the Voc. Anyway, when trying to stay under the max voltage of the charge controller you MUST use Voc, else you do risk burning up your equipment.

Your panels Voc is 51V, so three of those in series is 153V, which is higher than the maximum of 145V. That isn't taking temperature into account. If the temperature is below 25°C, the Voc will be higher than 51V - The more under 25°C the higher it will be.
 

syclonedriver

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If you have access to a clamp on DC amp meter they can be very useful then checking multiple strings of panels and batteries.

Horsefly has a point. You might want to try rewiring your panels to reduce the voltage. Your charge controller might be limiting its output to protect it's self.
 

syclonedriver

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What is the cable length from the panels to the junction box?
What is the cable length form the junction box to the charge controller?
 

abdallah.91

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an important
thanks @Horsefly for you attention,

I just checked again the PH18-5048 PLUS datasheet from Must company itself, please see attached a screenshot of its specifications table, the max pv serie open circuit voltage is 145V, and I checked in sunny day clear sky the voltage of each panel, no one exceeded 46v, so at max the 3 panels serie gave 137V. and that is the value which I read on the inverter display at very sunny times.
an important update appeared today after I checked each serie current, I used a resistive load (around 30 Ohm heater), when the sun appeared the current flowed in the load got close to 6 ampers each serie. I collected them in the inveter again and nothing changed, I gave up and got angry and I called an expert to help me, in that time I did an absurd act which is resetting parameters during operation and the surprise was that inverter feed the load 900W and charge the batteries 600W, I added many loads arround 3000w and the inverter still charging the batteries and feeding the loads. now what I am facing is that a little clouds in the sky the system takes from the batteries to help feeding the load even if the load is not more that 800w, so it takes for that 800w load around 400w from the bateries. if this is the normal case I don't think I will take more than 500 watt during the winter from that big system (5kw).
 

abdallah.91

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an important

an important update appeared today after I checked each serie current, I used a resistive load (around 30 Ohm heater), when the sun appeared the current flowed in the load got close to 6 ampers each serie. I collected them in the inveter again and nothing changed, I gave up and got angry and I called an expert to help me, in that time I did an absurd act which is resetting parameters during operation and the surprise was that inverter feed the load 900W and charge the batteries 600W, I added many loads arround 3000w and the inverter still charging the batteries and feeding the loads. now what I am facing is that a little clouds in the sky the system takes from the batteries to help feeding the load even if the load is not more that 800w, so it takes for that 800w load around 400w from the bateries. if this is the normal case I don't think I will take more than 500 watt during the winter from that big system (5kw).
is it possible that the Trinasolar panels efficiency isn't good enough?
 

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upnorthandpersonal

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Your max Voc is indeed 145V, but the MPPT range is up to 130VDC, which according to your measurements, you're exceeding:

I isolated all groups then I connected each one alone and measure the voltage just before the inverter, all were ok with voltage around 136V.

(Did you measure that under load when connected?)

I'm using panels with a similar voltage range, and I also use a MUST charge controller (same as the one in your inverter) without issues - but I only put two panels in series per string.
 

abdallah.91

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What is the cable length from the panels to the junction box?
What is the cable length form the junction box to the charge controller?
around 50 meters 4mm DC cable. if 150V Voc the 3 panels gives, it higher by 5V the max in the datasheet. is it dangerous? could damage the inverter?
 

abdallah.91

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If you have access to a clamp on DC amp meter they can be very useful then checking multiple strings of panels and batteries.

Horsefly has a point. You might want to try rewiring your panels to reduce the voltage. Your charge controller might be limiting its output to protect it's self.
is this 5V different damaging the inverter?
 

Horsefly

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is this 5V different damaging the inverter?
Your all-in-one has three separate things in one box: Inverter, Solar Charge Controller, and Charger. Exceeding the max input voltage from the PV array is not damaging the Inverter itself, but it is damaging the Charge Controller, or at least could. It almost certainly would over an extended time.
 
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