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I want to design an inverter that can manage 900V input, with maximum efficiency, the output can can be regulated with a transformer.

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gamal.mothersil

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I want to produce 230 volts with 30 A per face from solar panels. My belief is if a 12VDC battery bank can produce 220VAC, therefore, 48DC can produce 8,800ACV. I would settle for 8,000VAC to reduce heat, but is this possible. A single solar panel can produce 48VDC with 6A which is sufficient for producing 6.9kW maximum. I understand that in reality the output will max at 70% or 4830kW which is still adequate. My main question is can one 48VDC 6A solar panel produce my output, or it is better to add more panels and design a high voltage input inverter.

Gamal
 

A single solar panel can produce 48VDC with 6A which is sufficient for producing 6.9kW maximum.

Plain math says you get 288 Watts from the panel, average. (48 x 6)

Therefore you can get 36 milliAmps at 8kV from the panel. (288 / 8000)
 

Plain math says you get 288 Watts from the panel, average. (48 x 6)

Therefore you can get 36 milliAmps at 8kV from the panel. (288 / 8000)
What I meant is, a 48V battery bank with 10A should be able to produce 6.9kW based on the 12VDC to 220VAC inverters I have seen.
 

What I meant is, a 48V battery bank with 10A should be able to produce 6.9kW based on the 12VDC to 220VAC inverters I have seen.

P = V I
so 48 volts at 10 amps is 480 watts
nowhere near 6.9 kW

assuming a perfect transformer:
12 VDC to 220 VAC is a voltage step up by 18.3 (12 x 18.3 = 220)
which means that the current steps down by a factor of 18.3

energy (in the form of power) is conserved
so power on input Pin = Vin x Iin must equal power on output, Pout = Vout X Iout
so if voltage goes up by some factor, then current must go down by the same factor.

and there are always losses - copper losses due to resistance of copper wire in windings,
core losses due to domain shifting in the core
magnetization losses, etc.

if you want 6.9 kw from 48 V, you'll need 160 amps, assuming 90% efficiency
6900 W / 48 V = 143.75 amp
at 90% efficiency, 143.75 A / 0.90 = 159.7 amps, hence 160 amps
 

I understand what you are saying in reality, but I was wondering why I was seeing people use one 12 volts solar panel to operate appliances that uses up to 4 amps at 120V which is 480W. That solar panel should be producing approximately 60W.
I might use a DC Voltage amplifier to increase the DC Voltage from 10 solar panels to my required value, and that should provide enough power for the inverter.
 

Hi,

a battery is a storage for energy.

you may feed it for 1 hour with 60W.

then you easily may draw 600W for some minutes. But surely not continously.

*****
Current is like the flow rate of water. A bucket is like a battery.
Imagine a bucket and a very low stream of water to fill it up wihtin hours.
But you can empty the bucket within seconds.

Klaus
 
I want to produce 230 volts with 30 A per face from solar panels. My belief is if a 12VDC battery bank can produce 220VAC, therefore, 48DC can produce 8,800ACV. I would settle for 8,000VAC to reduce heat, but is this possible. A single solar panel can produce 48VDC with 6A which is sufficient for producing 6.9kW maximum. I understand that in reality the output will max at 70% or 4830kW which is still adequate. My main question is can one 48VDC 6A solar panel produce my output, or it is better to add more panels and design a high voltage input inverter.

Gamal
PV impedance matching from the MPPT controller is critical where Z=Vol/Isc and also Pmpt = Vmpt * Impt, where losses increase with I^2R thus raising battery voltage is desirable with Pmpt to minimize conversion losses to some current max. to reduce the cost of cables and bridge drivers.

But 48V 6A is < 500W and not anything close to 5kW. 10A is a reasonable limit so if you wanted > 5kW, you would consider ~ 500 V battery string with BMS balancing and not 50V*100A
 

Hi,

a battery is a storage for energy.

you may feed it for 1 hour with 60W.

then you easily may draw 600W for some minutes. But surely not continously.

*****
Current is like the flow rate of water. A bucket is like a battery.
Imagine a bucket and a very low stream of water to fill it up wihtin hours.
But you can empty the bucket within seconds.

Klaus
Thank you for responding. The sun is the only input, therefore, I am okay when the power drops below a certain value.
--- Updated ---

Hi,

a battery is a storage for energy.

you may feed it for 1 hour with 60W.

then you easily may draw 600W for some minutes. But surely not continously.

*****
Current is like the flow rate of water. A bucket is like a battery.
Imagine a bucket and a very low stream of water to fill it up wihtin hours.
But you can empty the bucket within seconds.

Klaus
I am okay with the sun as the only input. This will be a daytime power source.
 
Last edited:

Hi,

There is energy and there is power.

Battery:
You first need to input some ammount of energy into the battery before you can pull it out. But there is loss, thus you always have to put in more than pull out.

Energy = P × t.
So you are free to use high power and short time ... or low power for long time..
For both input and output.

Klaus
 

Thank you for responding. The sun is the only input, therefore, I am okay when the power drops below a certain value.
--- Updated ---


I am okay with the sun as the only input. This will be a daytime power source.
Thank you one and all for the information. Finally I decided that I will use 12 400W solar panels and I will settle with the output. I can use 12 panels in series with a 600v input, or (2) 300v input to two inverters. I will not use a battery bank so this will be a sunlight power source. I will use a circuit or device to turn off the power at 800W or less. I want 230AC volts at the output, but that can be achieve with the proper transformer. I want insight on where to start with this project. For ex. which inverter is more efficient, will a huge capacitor's bank help to regulate the output. Thanks in advance for your reply.
 

I gained experience from my backup home power system made from PV panels, battery bank and power inverters. A store-bought inverter is likely to have built-in safeguards requiring that the power source be inside a certain voltage range, or it refuses to work.

Example, a. 12V inverter might work only when fed voltage between 10.5 and 16 volts. This is normal spread for lead-acid batteries charging and discharging. The battery acts as both storage bank and voltage stabilizer.

This means if you wish PV panels to be the power source, then you must install some kind of regulating circuit before the inverter, to do the stabilizing job normally done by the battery.

A PV panel varies its voltage depending on current draw. Maybe 22 V with no load. Voltage drops quickly as you draw power. You must somehow reduce voltage so the inverter accepts it on startup, then immediately begin regulating voltage to cooperate with current demand which is not always predictable.

If the inverter doesn't like the supply voltage, then expect it to shut down.
 

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