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How many panels to run a 1hp air conditioner?


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RogerDat

So how many of these panels would be needed to run a 1HP window AC?

 

Is it amps x volts = watts?  4.8 x 220 = 1056 watts or 11 panels?
 

Edited by RogerDat
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Paul

If you are talking about off-grid, trust me, you would be much better off going with grid power, as apposed to doing that. Simply put, it would NOT be cost effective. And, that is only if you were running your a/c for a few hours per day. 

 

A lot of people think that going off-grid for solar is cheaper. It is not cheaper than paying the power company, even in the Philippines. Not even close. 

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Paul

In all honesty, prior to going with an off-grid, or even a grid-tied system, one should work on three things: 

 

1. Conservation - What can you do without, or turn off for more hours each day? Save power, rather than using it unnecessarily. (I waste a lot, myself.)

2. Insulation - Make the room(s) you wish to cool as insulated as possible, to cut down on the compressor cutting on so often. Use natural lighting in homes, where possible, during the day. 

3. Buy Energy Efficient Appliances - Purchase the most energy efficient appliances you can. This includes, but is not limited to, inverter refrigerators and air-conditioners.

 

If you start doing the above things first, it will save you a TON of money on your current power bill.

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hyaku

We bought 1 and 3 watt LED bulbs, inverter ref, LED TV etc. and our bill is P300 peso down. I checked prices again after yesterdays post on cheap panels at CDR King. I worked out I would have to get a least four years service to run even with the amount I pay to the electric company.

 

The inverter ref is the best thing they invented after sliced bread. Even on the lowest setting my drinks are so cold they are on the verge of iceing up.

Edited by hyaku
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thebob

So how many of these panels would be needed to run a 1HP window AC?

 

Is it amps x volts = watts?  4.8 x 220 = 1056 watts or 11 panels?

 

 

It's a bit more complicated than that. Starting the unit can demand several times that because of "inrush current".

 

Starting current is referred to as "Locked Rotor Amps" (LRA) and is typically 3-8 times the continuous operating current. To complicate this even further, on start up the "Power Factor" is quite low. Also on starting, voltage drops and this also reduces the starting current, typically this is about 30%.

 

Some units have "Starting Amps" written on the nameplate, otherwise you will have to measure it with a clamp on meter.

 

So to recap an AC might "run" at the rated current, but it almost certainly won't start. Adding a "Hard Start" can help a lot. It is large capacitor in series with a relay. Retrofitting these is non trivial, but a good electrical engineer should be able to help you.

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RogerDat

I graduated HVAC in 2000, and know about the LRA, but was hoping updates have been made.

Our lights flicker all day, and AC goes off due to low voltage several times an hour. We get down to 190 volts much of the day.

Our house is at the end of the run from transformer, and any welding causes havock. MECO is out looking over neighborhood for culpret, most welding shops here bypass the meter, so once they find it, all will be well for a few months till the next shop sets up.

I have 12 VDC lED lights for the most paret, but its motors that cost big time to run.

 

Did I start this post, or was it split off???

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Paul

 

 

Did I start this post, or was it split off???

 

I split it from the other thread, since it deserved to be its own topic.

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Bill H

It's worse than you think.  DC batteries do a very good job of running small loads like lights and fans, but they do not handle large loads with high-current demands well at all.  Appliances like refrigerators, air conditioners, electric dryers, and anything run by an electric motor above 1hp simply overwhelm the ability of the batteries to supply the proper current.  Keep in mind if your battery bank is rated at 600amp hours you in reality only have 300 ah available to do actual work in a lead acid battery based systems.  That said, I don't fully agree with Paul regarding using the grid.  The grid in the PH is very unreliable in many areas, so what is the point on building a system which relies upon it?  The better option I think is a diesel generator to handle those large heavy loads, cloudy days and nighttime use.  The primary purpose of an off grid system is to keep your electrical gadgets running when the power fails, not as Paul pointed out, to save money on your electrical bills.

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littlejohn

Cant possibly afford an offgrid system myself so would like to have a hybrid system to keep the power stable all the time even up to 4 hours down and use solar to lower the cost of power but just enough to cover the load when the sun is shinning.

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fred42

It's worse than you think.  DC batteries do a very good job of running small loads like lights and fans, but they do not handle large loads with high-current demands well at all.  Appliances like refrigerators, air conditioners, electric dryers, and anything run by an electric motor above 1hp simply overwhelm the ability of the batteries to supply the proper current.  Keep in mind if your battery bank is rated at 600amp hours you in reality only have 300 ah available to do actual work in a lead acid battery based systems.  That said, I don't fully agree with Paul regarding using the grid.  The grid in the PH is very unreliable in many areas, so what is the point on building a system which relies upon it?  The better option I think is a diesel generator to handle those large heavy loads, cloudy days and nighttime use.  The primary purpose of an off grid system is to keep your electrical gadgets running when the power fails, not as Paul pointed out, to save money on your electrical bills.

 

 

 

Well the guy in this video seems to be running an A/C window unit with just 520 watts a couple of batteries and an inverter..

I dont think he mentions though the size of the A/C.

 

 

520 Watts in panels. 2500/5000 peak watts inverter. 3 marine batteries. 620 watts AC. Two 30 Amps charge controlers. 

Edited by fred42
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Woolf

The batteries and the inverter  needs to be able to provide the start up current

 

But I do not think that he will be able to run the a/c for 24 hours without running down the batteries

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fred42

The batteries and the inverter  needs to be able to provide the start up current

 

But I do not think that he will be able to run the a/c for 24 hours without running down the batteries

 

 

I dont think he`s using deep cycle batteries and he reckons the batteries last about 3 hours at night.. He says in the comments that these days he runs the A/C all day off the grid tie.. 

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thebob

 

 

The batteries and the inverter  needs to be able to provide the start up current

 

I think the deal here is that a regular AC unit isn't the best unit to try and run on 12V. There are just too many phase transitions in the way. Power from the array, into chemical in the batteries, and back to electrical to the inverter and then in the inverter, and finally electrical to mechanical in the AC unit.

 

I'd guess that an automotive AC pump powered by a Brushless DC Motor would be more efficient. And I'd guess that what you need is some kind of thermal mass that is chilled at a constant rate, and the thermostat only operates on the fan circulating air through that thermal mass. Some kind of storage chiller so that you can save the excess energy from the peak periods of the day thermally and release it when needed. A big insulated tank of glycol or saturated salt solution or something.

 

I've often thought of powering an automotive AC from mains with an electric motor, and having an electric clutch and a 5hp diesel motor to run it during blackouts. Even a larger unit from a bus and a bigger motor.

 

I think half the battle is just designing a a cool house in the first place.

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RogerDat

Think ammonia

In the early years of the twentieth century, the vapor absorption cycle using water-ammonia systems was popular and widely used, but after the development of the vapor compression cycle it lost much of its importance because of its low coefficient of performance (about one fifth of that of the vapor compression cycle). Nowadays, the vapor absorption cycle is used only where waste heat is available or where heat is derived from solar collectors. Absorption refrigerators are a popular alternative to regular compressor refrigerators where electricity is unreliable, costly, or unavailable, where noise from the compressor is problematic, or where surplus heat is available (e.g., from turbine exhausts or industrial processes, or from solar plants).

Absorption cooling was invented by the French scientist Ferdinand Carré in 1858.[2] The original design used water and sulphuric acid.

In 1922 Baltzar von Platen and Carl Munters, while they were still students at the Royal Institute of Technology in Stockholm, Sweden, enhanced the principle with a 3-fluid configuration. This "Platen-Munters" design can operate without a pump.

Commercial production began in 1923 by the newly formed company AB Arctic, which was bought by Electrolux in 1925. In the 1960s, the absorption refrigeration saw a renaissance due to the substantial demand for refrigerators for caravans. AB Electrolux established a subsidiary in the United States, named Dometic Sales Corporation. The company marketed refrigerators for RVs under the Dometic brand. In 2001, Electrolux sold most of its leisure products line to the venture-capital company EQT which created Dometic as a stand-alone company.

In 1926, Albert Einstein and his former student Leó Szilárd proposed an alternative design known as the Einstein refrigerator.[3]

At the 2007 TED Conference, Adam Grosser presented his research of a new, very small, "intermittent absorption" vaccine refrigeration unit for use in third world countries. The refrigerator is a small unit placed over a campfire, that can later be used to cool 15 liters of water to just above freezing for 24 hours in a 30 degree Celsius environment.[4]

!

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