Solar powered AC air conditioning, a bummer or a challenge?

[russ]

Philly, You can find anything one wants on youtube - for, against and could care less on any topic. Maybe 95% of youtube posts are just some fool with a video camera that wants to act like an expert but knows nothing.

The capacitors for power factor improvement are an old and long running scam. I seriously doubt those are engineers trying to sell it and even if they are engineers they are still thieves. In the US, residential power costs would not really change - one is not billed in that manner.

Commercial is a different story and should not be confused with residential.

[Mike90250]

The capacitors I am talking about are 5F and 10F at 35V designed for use in 12 volt systems to handle the hi serge in stereo amps (I use one 'AT' my mobile HF amplifier to help with the peaks on side band). The 12 Volt compressors designed to run straight from the solar panel without any charge controller or inverter use panels rated at 12V with 22V peak.

The fan motor on all of the larger AC units I am aware of will not start without a capacitor. The capacitors give a DC Jolt to the AC motor to start it spinning, then it runs on AC. Capacitor start AC motors have been around for a long time it helps keep the size and expense down. And as I said I do not know of any capacitor that will start a 120 AC unit.

Many engineers seem unable to understand how things really come together to make things work.

When the reader is not able to understanding what the writer is writing about, it does not mean that the writer does not know what they're talking about.
Abe

I know very well what you are trying to talk about, and will now just let your words stand - by themselves in misconception corner.
In actuality, the inductance in your DC wires, swamps out most of the available capacitance. And AC motor caps (both Run & Start) have nothing to do with DC, which would instantly damage an AC motors windings. I tried to hint at the phase relationship in my earlier comment, but was apparently too obtuse.
About the only thing I can agree with you this week, is that some 12VDC gear will run directly from PV panels.

[SunEagle]

Power factor correcting capacitors

Both Sunking and russ are correct about capacitors doing nothing to reduce a homeowners electric bill. They can reduce the cost at an industrial facility that has a power factor penalty and gets billed for it being below what the Utility decides it should be.

Of course you now have the problem that capacitors can increase costs due to the harmonic distortion they generate. This distortion will affect all types of equipment in the facility by reducing the "power quality" of the electrical distribution system and increasing losses (overheating motors and variable frequency drives) due to that distortion. To rectify that you will need to use a combination capacitor with harmonic mitigating hardware like an LC Filter or phase shifting a couple of transformers which cancels out some of the harmonics. There are lots of ways to improve power factor and reduce harmonic distortion which will save a facility a lot of money over a period of time.

[paulcheung]

It is complete FRAUD. For starters there are not enough inductive loads to worry about in a residence. Industrail is different where the can be running multiple large horse power motors.

But the nail in the coffin, is utilities do not monitor, record. or bill for Vars. So those folks who claim it lowered their bills are brainwashed. Utilities only charge for True Power, not VARs

So the bad power factor equipment does not affect the true electrical consumption? the amperage and the watts reported from the kill-a-watt meter or the clamp amp meters tell the true consumptions? I don't have to worry any bad power factor as long as my inverter can manage the load? That will be good news!
Thank you guys.

[russ]

So the bad power factor equipment does not affect the true electrical consumption? the amperage and the watts reported from the kill-a-watt meter or the clamp amp meters tell the true consumptions? I don't have to worry any bad power factor as long as my inverter can manage the load? That will be good news!
Thank you guys.

By US rules the power factor is a problem for the utilities - elsewhere may be different. Where I live now is like the US in that regard.

[inetdog]

So the bad power factor equipment does not affect the true electrical consumption? the amperage and the watts reported from the kill-a-watt meter or the clamp amp meters tell the true consumptions? I don't have to worry any bad power factor as long as my inverter can manage the load? That will be good news!
Thank you guys.

The low power factor equipment may require larger AC wiring, since the wiring is sized based on the current it carries. And all inverters will have a limit on the maximum VA they can deliver, which may be a little as 5% or as much as 30% higher than the wattage limit. The watts rather than the VA will determine the power drawn from the batteries though.

[billvon]

So the bad power factor equipment does not affect the true electrical consumption?

It does not directly affect the power your meter reports, which is what you pay for.

I don't have to worry any bad power factor as long as my inverter can manage the load?

For reasonable power factors - no. If you make the load capacitive or inductive enough your inverter won't be able to handle it, of course. But 99% of the loads out there won't be a problem.

[inetdog]

It does not directly affect the power your meter reports, which is what you pay for.

For reasonable power factors - no. If you make the load capacitive or inductive enough your inverter won't be able to handle it, of course. But 99% of the loads out there won't be a problem.

Although the inverter spec may indicate an allowed power factor only, be aware that not all circuits can handle a capacitive low power factor (rarely ever seen except with switching power supplies and some lighting loads) as well as they can handle an inductive low power factor.

[billvon]

Although the inverter spec may indicate an allowed power factor only, be aware that not all circuits can handle a capacitive low power factor (rarely ever seen except with switching power supplies and some lighting loads) as well as they can handle an inductive low power factor.

Well, I think you're talking about two different things here.

One is a capacitive (leading) power factor, which is the converse of the inductive (lagging) power factor. That does indeed give inverters trouble; fortunately it is very rare, since no one puts large pure capacitive loads on AC power. About the only way I could see that happening is if an inductive load with power factor correction caps suddenly loses its inductive load due to a breaker tripping or something.

The other is nonlinear loads, or loads with high harmonic content. These are also harder for inverters to drive, and are generally caused by peak rectification in older power supplies and electronic ballasts. The result of this is that the current waveform is very "peaky" - it might only deliver current for a few milliseconds out of an 8 millisecond half-cycle. The reason this is such a problem is that to deliver (say) 10 amps to a load, you might have to deliver 40 amps at the peak of the waveform and almost nothing for the rest of the waveform. Thus the inverter has to deliver 40 amps instead of 10 for the same load, leading to problems that range from overheating and buzzing to blown output stages. It also leads to nasty problems like neutral currents that can be several times higher than any of the phase currents.

Fortunately modern large power supplies are required to incorporate power factor correction to reduce this problem.

[inetdog]

Well, I think you're talking about two different things here.

One is a capacitive (leading) power factor, which is the converse of the inductive (lagging) power factor. That does indeed give inverters trouble; fortunately it is very rare, since no one puts large pure capacitive loads on AC power. About the only way I could see that happening is if an inductive load with power factor correction caps suddenly loses its inductive load due to a breaker tripping or something.

The other is nonlinear loads, or loads with high harmonic content. These are also harder for inverters to drive, and are generally caused by peak rectification in older power supplies and electronic ballasts. The result of this is that the current waveform is very "peaky" - it might only deliver current for a few milliseconds out of an 8 millisecond half-cycle. The reason this is such a problem is that to deliver (say) 10 amps to a load, you might have to deliver 40 amps at the peak of the waveform and almost nothing for the rest of the waveform. Thus the inverter has to deliver 40 amps instead of 10 for the same load, leading to problems that range from overheating and buzzing to blown output stages. It also leads to nasty problems like neutral currents that can be several times higher than any of the phase currents.

Fortunately modern large power supplies are required to incorporate power factor correction to reduce this problem.

True, and the difference between the two types of low power factor is usually categorized as displacement power factor (linear loads with capacitive or inductive components) and distortion power factor (non-linear loads in general.)
However, all other things being equal, a power supply which charges a capacitor from the peak of the AC waveform will exhibit both a displacement component and a distortion component to the low PF. The displacement portion will be capacitive in direction.

[Hkalan]

Hello,

As I live off-grid, and I have had this same dilemma of air conditioning (I am in sub-tropical climates). I have taken the bull by the horns, and have been exploring the "Peltier" technology. I have been getting some great results by falling on my face and learning form mistakes... But it is paying off in the end.

Here is the first unit I had made...

I am quite happy with the first test !!!

Alan

[Hkalan]

Hello,

I then had to think about the larger rooms !!! So me and a few friends did the math, and designed a big unit...

Could be a good the answer !!!

Alan

[Hkalan]

Hello,

Now that I have the machines, It is time to do some testing... The smaller unit first !

I am pleased !

Alan

[Hkalan]

Hello,

The results are fantastic, so time to test the big unit !

One step forward !

Alan

[Hkalan]

Hello Again,

Now this is the latest test that same afternoon...

Overall... we can get Air Conditioning without AC power... we just need to think outside the box and do it for ourself !!! I am quite sure no oil company is going to support us !!!!

Alan