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I have a 48 volt mppt controller that can handle 3200w,60A and 185 volts. I need 2000w 37A to run a/c unit on car trailer. If I run panels in series at higher voltage witch gives lower amps will the amp go back up when the controller drops the voltage down or do you lose the amps & watts when in series. THANK YOU JOHN
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Last edited by NEOH; 10-24-2017, 10:26 PM. -
thank you for the fast reply.
how many watts should I use for that kind of consumption.Comment
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ZERO without a few hundred pound of batteries.
To answer your question, I will teach you how to find the answer. Real simple Math
MPPT Output Current = Panel Wattage / Battery Nominal Wattage
I assume you intend to use a 48 volt battery, or at least I hope so because that is the only way you can do it, 12 or 24 will not work. 2000 watts / 48 volts = 41.66 max amps output to battery/load.
MPPT controllers are Power Converters, not Voltage Converters like PWM controllers. The whole point of using MPPT controllers is two fold:
1 It allows you to use much larger, higher voltage Grid Tied Panel which cost 1/3 what lower power battery panels cost. Major dollar stretcher. .
2. As a extra benefit it allows you to run higher voltages on the panels within limits. Depends on the controller. Most MPPT controllers but units that can operate at 48 volt battery usually range from 150 up to 600 volts DC. That means a lot more money saved. It allows you to wire panels in series keeping the wires smaller and fewer runs. To the point you do not need any combiners and fuses which are very expensive.
So here is what you need to know. A MPPT Controller is a Power Converter.
Power in roughly = Power Out
Current and voltage are dependant on each other. We already know Power = Voltage x Current. So the take away here is Power is the product of voltage and current. So if you know the Power, you can figure out voltage or current if you one or the other. Output is easy. What battery voltage right? 2000 watts / 48 volts = 41.6 amps ring a bell?
So what voltage is the Input from the panels. BTFOOM what the voltage is from the panels. You tell me. Add up the Vmp of the panels in series. I will tell you it must be greater than about 70 volts, or else will not charge the batteries under all conditions. You want it as high as possible without sacrificing controller efficiency. So lets say you have 30 volt Vmp panels with 3 in series = 90 volts. What would the current be?
Current = Wattage / Voltage.
Where have we seen that simple math?
2000 watts / 90 volts = 22.22 amps going in.
So on the Input you have 90 volts @ 22.2 amps, and on the Output you have 48 volts @ 41.6 amps. No matter how you spin it, 2000 watts in, and 2000 watts out. Voltage and Current is what it is.
Last edited by Sunking; 10-25-2017, 05:22 PM.MSEE, PEComment
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thank you for the info I am running 4 group 29 batteries for now in series to a 3000w 48v to 120v inverter the controller will handle 3200w 60a and 185v.
I do not no what batteries I should use. I was looking at the jinko 295w panels. I can fit 9 on roof.
THANK YOU JOHNComment
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295 Watt PV x 9 x 80% = 2,124 Watts from PV
That is enough power to operate the 2,000 Watt A/C Unit during the day with full sunshine.
But what about charging the batteries in a reasonable amount of time?
Duty Cycle ?
How often will the A/C run ?
25% = 15 Minutes every hour?
33% = 20 Minutes every hour?
Do you plan on running the A/C at night?Last edited by NEOH; 10-31-2017, 07:39 PM.Comment
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some times the a/c will run all day long at the track it can be 115f at times. I thought about using a swamp cooler to keep the draw down but it wold be nice to run the a/c unit all day and
for a few hours at night. so what would you do for panels and batteries for these type of conditions.Comment
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