running a airco 24000btu

robocop

Hi

Considering  that I will not use no battery for now . How many watts total in panels do i have to use.

Airco 2000w running 2600 starting  inverter 5kva/4000w continious  48v dc

I think of 9 panels of 340w each will do the job, in the night if I will use the airc will put battery .

I think for 3 hours 4 batt of 100ah/12v will do the job.

live in Curacao where there is sun almost the whole year-tropic.

one other question on inverter  it says there is input 90-280v for comp et etc I do not understand that,

One thing I know  there is for instance 48vdc input and 200v or 110v or combination.

Beginning to understand the solar matter thanks to all of you

Rregards

 

Estragon

I think you will need at least some battery and a charge controller, even for daytime use. Is the inverter designed to be hooked up directly to PV? What is the make/model number?

For night use, to run ~50a@48v for 3 hours is 150ah. Minimum size for that would be around 300ah@48v. 8xL16 type 6v batteries in series would be a good way to do this if available locally, or 16xGC type 6v in 2 parallel strings. GC size deep cycle batteries are often used for boat house banks so should be available locally. This is minimum size, and assumes you will be able to reliably charge the next day.

9 panels @ 340w should be fine to charge a bank this size.

mvas

Without a battery bank, how will your Solar Panels provide the 3 TIMES start-surge for the compressor ?

Estragon

@mvas

He said 2600w starting.

mvas

Estragon said:

@mvas

He said 2600w starting.

Yes I saw that, but I do not believe it.

If this thread, is another discussion of the Daikin 24,000 BTU Mini-Split from the other very similar threads started by robocop,
and I think it is, then per Daikin the AC Power specifications are:
"... Requires 18.3 amps @ 240 Volts AC via Dual 20 Amp Breakers ..."

18.3 amps @ 240 Volts = 4,392 Watts ( start-up )

Robocop's plans are: 9 Panels x 340 Watts x 80% = 2,448 Watts output from the Inverter.
I do not think that 10 Amps @ 240 Volts is enough to start the compressor, that requires 18.3 amps.

Estragon

I was dubious too. Could he hook panels up directly to the inverter, even assuming the 2.6kw is correct?

mvas

Yes you "can", but  ...

There will be no MPPT and it works only if your load draws less than "Imp" amps ( Imp = Amps at Max Power Point ) from the PV Panel. The voltage is quite stable when the amps drawn is always less than "Imp" amps.  At "Imp" amps, the Voltage will typically be at or above 80% of Voc. It's called, "operating above the knee of the I-V curve". The PV Panel is in "voltage mode".  If the 48 Volt inverter can handle the voltage range from Voc down to 80% Voc then the Inverter will work just fine.  But if you ever try to draw more amps than "Imp" amps then the PV Voltage will drop very quickly and the inverter would temporarily shutdown. Simple solution - use a very constant load that won't ever draw more than "Imp" amps per string (just slightly less is best). This is how many/all PV Powered devices operated, before we had MPPT circuitry (the old days).  But robocop has an Air Conditioner Compressor as a load. And I say, the Start Amps is significantly larger than the Run Amps and that is why I think robocop will need a battery bank. His load is the exact opposite of "constant".

Two "48 Cell / 24 Volt" PV Panels wired in series could produce between 60 Volts (Voc max) and 48 Volts (Vmp @ Imp). There are some 48 Volt DC-to-AC Inverters that will work with input voltages between 62 volts (max) and 41 volts (min). So yes, if you happen to have two 48 Cell / 24 Volt PV Panels wired in series and you happen to have a 48 Volt DC-to-AC Inverter with a wide input voltage then voila you have "quick & dirty" way can make usable 110 V AC without a battery.

Estragon

Thanks, that's pretty much what I thought.

So as soon as a cloud rolls by, the voltage gets dragged down to the inverter LBCO. When the cloud passes, the inverter starts again and short cycles the AC before gas pressure equalizes. Even if the 2.6kw was right it's likely much higher on a short cycle.