Generate amps or Generate watts?

9 Posts
Sep 13, 2008 10:10 am
Generate amps or Generate watts?

There is an equipment that generates 450amps AC and this equipment is a water generation machine (Dehumidifier) not a pumping machine it extracts water from the atmosphere and converts it to drinking water. We are not sizing for a battery backup just sizing for solar panels and inverter cause there will be no batteries involved. Please can your come up with the number of panel we need to power this equipment for a day and the machine is to work from dawn till dusk. I need to know the sizing of the panels, inverters and any other thing you think we will need but there will be no battery charger as there is no battery. What voltage do you think we should use,48 VDC or ? Is it possible to use the solar panel to generate the amps and power the amps at 48v instead of generating power for the watt with the panels? I think we can power amps. Using an inverter 48V 450amp should generate 450amps and 220v across the inverter. Is this possible?
220 Posts
Sep 13, 2008 11:51 am
Re: Generate amps or Generate watts?


  this post makes no sense to me? either it is way over my head or we have have a communications problem. we need to go to the equipment or spec sheet from the manufacturer and get the power requirements. get all the numbers you can find with any letters with those numbers such as w, v, va, a, ac, dc, hz or other combinations of letters and numbers. or just copy the whole sticker.

 could this machine of yours be (generating) 450 ampules of water per hour? where did that 450amps come from? thats alotta juice.

good luck.
9 Posts
Sep 13, 2008 12:20 pm
Re: Generate amps or Generate watts?

Please can you send me your email so i can send you the specification sheet. It is a PDF document.
9 Posts
Sep 13, 2008 12:31 pm
Re: Generate amps or Generate watts?

Please can you send me your email so i can send you the specification sheet. It is a PDF document.
220 Posts
Sep 13, 2008 02:14 pm
Re: Generate amps or Generate watts?

 fantastic! you have the spec sheet.

 my dial up is very slow downloading files of any size and to keep this a true open forum we can stick that pdf file into a free file sharing site for all to have a peak at.

 i just put this 600kb photo up. heres a link-sort of

 you will have to cut and paste because i still have not figured out how to post a live link here.

 ok so post it at sendspace and provide the file id back here and the forum can have a go at being of some help.

 all the best
9 Posts
Sep 13, 2008 05:50 pm
Re: Generate amps or Generate watts?

I have uploaded the data sheet of the dehumidifier in this link
Please do look at it and tell me if using solar to generate amps instead of watts will power the equipment.
Sep 13, 2008 06:55 pm
Re: Generate amps or Generate watts?

Be prepared to dig deep into those pockets my friend because a PV array for this ain't gonna be cheap.
You will see on page 2 of the file;
voltage 220/3/50
FLA 398.1
That means 220 volts/ 3 phase / 50 Hertz
Full Load Amperage 398.1

Figuring 3 phase wattage is a little different than figuring single phase wattage.

Multiply 398.1 times 220 times 1.732 = 151,692 watts divided by 1,000 = 152 kilowatts

You will have to know the number of hours of equivalent full rated power from a PV module you can expect in your region. I will guess 5 hours of equivalent full rated power per day. So...
152,000 watts divided by 5 = 30,400 watts of PV array at the very least.
At US $5.00 per watt not installed thats, US $152,000.00 at the very least. Chances are good that you will have to double the size of this PV array to 5 hours of water production per day.

Here is something a little smaller. It can produce 500 liters per day.
220 Posts
Sep 13, 2008 07:12 pm
Re: Generate amps or Generate watts?

  wow! you were not kidding when you said you need amps to power this unit. thats 450amps at 220vac.

  you are not gonna like this but lets look at the numbers.
  first off amps, volts and watts are like the holy trinity of power. when we have any two in the equation we can find the third. ie volts x amps = watts or watts / volts = amps
so for example we have a 200 watt pv module with a voltage of 24 volts we get 200/24=8.3 amps

 now for the bad news.. our example has 450 amps @ 220 volts 450 x 220 = 99,000 watts of pv! the price tag on that kind of array at $5.00 per watt is a half million dollars. and that is before any derating and other required components.

 i'm sorry the news is not better but it looks like a pv solution would be difficult in this installation. perhaps a big diesel generator would be more practical.

best of luck!
351 Posts
Sep 14, 2008 04:02 am
Re: Generate amps or Generate watts?

It looks like you sized the array for the hourly requirement, not the daily.

The "dehumidifier" needs to run 24 hours a day to produce the 1700 gallons a day. The best production is at night, as the temperature drops.

So, you are pushing 2400kWh a day, possibly more depending on temperature, humidity, etc. 5 hours of sun would make that array at least 480kW. 

I don’t even want to think about a battery bank for that much energy.

« Last Edit: Sep 14, 2008 04:15 am by ken hall »
Sep 14, 2008 08:48 am
Re: Generate amps or Generate watts?

Smith Oshodin, you do realize that this machine works under the exact same principles as refrigeration? That is, evaporation of latent heat.
Imagine an open pot of water boiling at 212 F on the stove top in the kitchen on a cold winters night. The steam rises and condenses on the cold glass panes of a window. You have probably notice how there is almost always a puddle of water around most air conditioners that are in operation.
Some liquids boil at temperatures below 0 F. These are called "refrigerants." Ammonia is a refrigerant, it boils at -27 F.

Refrigeration was invented before the advent of modern day poly-phasic alternating current electricity.

It must be an arid dessert where you want to supply water to a large number of people and or crops to need such a large atmospheric condenser? 
Here are some ideas, just to ponder over.
When you get to this one click on "industrial" first.

If there is way to refrigerate, then there is a way to condense atmospheric humidity. Electricity does not have to be a part of the equation.
Electricity is not a necessity for life on Earth, it is a desire of those that live on Earth.
351 Posts
Sep 14, 2008 11:33 am
Re: Generate amps or Generate watts?

Whoops, I forgot that the OP had originally specified no batteries.
So, the array would be somewhere between 100kW and 150kW, depending on the peak daytime temperature and humidity.
Water production would drop way off. My guess would be somewhere around 350 gallons a day, depending on exact temp and RH.

I don’t think the intended location is an arid desert. This type of device works best under high humidity. My guess would be someplace in the tropics.

If Smith would spell out the problem, where he is trying to put it, how many gallons a day is needed, etc, we might be able to help solve the problem.

9 Posts
Sep 14, 2008 05:12 pm
Re: Generate amps or Generate watts?

Everyone has spoken wisely but the question is like David said amps,volts and watts are like the holy trinity of power.In your example you said that if we have a 200 watt pv module with a voltage of 24 volts we get 200/24=8.3 amps, which means we get 8.3amps from a 200w-24v solar panel. Is we decide to generate 450amps can we not now say 450/8.3=approximately 55, which means that 55 200w 24v solar panel will generate 450apms right? If this is so why can we then power450amps with 55 200w 24v solar panel? IS this possible?
220 Posts
Sep 15, 2008 01:21 am
Re: Generate amps or Generate watts?

 it is good to see that you are trying to understand the relationship of power. the volts, amps, and watts are all tied together in unbreakable rules. here is a link (maybe) that helps to show how they relate and they have a useful ohms wheel. the "rosary" of power if you will.

  if we take our 200 watt pv module at 24 volts equals 8.3 amps example. 200/24=8.3 we can express it as 24x8.3=200 or 200/8.3=24.they are all the same. now lets see how the relationships change with voltage. lets try 12volts in our formula. 200/12=16.6 amps. how about 48 volts thats 200/48=4.1 amps. these examples are all still the same amount of available power. lets try one about 220 volts. 200/220=0.9amps.

  now our approximate equipment requirements for this exercise 220 volts and 450amps (thats without the needed 3^ calculation thomas mentioned) we have the following         ?watts/220volts=450amps. or 450x220=99,000 watts of pv for a pv direct scheme.

 don't be discouraged, keep looking for a solution to your goals. (what are the goals exactly) there is more that one way to skin a cat. so keep at it.

  here is something interesting about making potable water from very dirty supplies even sewage!

best of luck, 73
« Last Edit: Sep 15, 2008 02:17 am by david ames »
9 Posts
Sep 15, 2008 02:16 am
Re: Generate amps or Generate watts?

In my last reply is the theory possible. Since there is an inverter involved
220 Posts
Sep 15, 2008 02:25 am
Re: Generate amps or Generate watts?

 well in theory anything is possible. but in practice only things that are possible are possible.

so i would say no. even with two inverters.

good luck
9 Posts
Sep 15, 2008 05:43 am
Re: Generate amps or Generate watts?

Base on the financial implication of using solar panel can any advice what other type of renewable energy could be used to power this equipment during the day and at night. This equipment was installed close to the creek. The amount of diesel spent daily on this equipment is killing and economical draining.
351 Posts
Sep 15, 2008 08:14 am
Re: Generate amps or Generate watts?

How many gallons of drinking water do you need a day ?
Why are you trying to take it from the air, instead of the creek.  Is there something wrong with the water ?
462 Posts
Sep 15, 2008 10:24 am
Re: Generate amps or Generate watts?

A creek nearby? If you cannot take water from the creek directly, either because of contamination or volume of water present, perhaps you can use the water itself in a condenser. It would work the same as your very powerful refridgeration unit you plan on buying. But instead of pumping R12 and using several compressors, perhaps you can pump the creek water through tubing or fins. Then you can return the water back to the creek. The cooled tubing would create condensation just as the "dehumidifier" type of device you are planning on using. Pumping creek water may prove more cost effective power wise.
  If the creek has enough flow and volume to remove the required volume of water needed, solar distillation, water pasteurization and filtration may be an option at little or no cost for power. Distribution can be solved using smaller DC pumps each with their own small PV and/or battery.
« Last Edit: Sep 15, 2008 10:27 am by Tom Mayrand »
9 Posts
Sep 15, 2008 03:36 pm
Re: Generate amps or Generate watts?

we would like to generate about 2,500-3,500 galoons of water per day. Could you tell us any equipment that would do the job without the input of diesel generators cause there is no electricity around where these equipments are installed. We want the equipment to be standalone and have there own natural source of power.We are also trying to be cost effective. i would appreciate if there are two solution one from the creek and the other from the air. Can we also has link to images of the equipment or site where we can see them.You guys have been great!
163 Posts
Sep 15, 2008 04:31 pm
Re: Generate amps or Generate watts?

The best thing for you is to contact some UN Development Agency that specialises in assisting developing nations with clean water options. Once the professionals in the field have identified the best solution(s) for your requirements, you can come back and get assistance with how best to power that option using renewable energy.

All of those "water from air" machines are basically scams. They will certainly produce water from air (as does any air conditioning unit), but water is a by-product of the process and more than 90% of the energy that goes into the unit is spent doing something else.

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