Solar Hybrid Inverter extreme Power Factor - Page 1
Forum section: electronics / beginners

author: hgg
author_rank: Frequent Contributor
timestamp: May 13, 2023, 04:51:21 am
content: Hi,I am using a new 3kW hybrid inverter made by Phocos and I've noticed something unusual.I have installed in the house the OWL power meter that connects to the main grid entry point with current clamps.When the battery gets depleted during late afternoon, the inverter switches immediately to grid power.Then when the loads (400W) connected to the inverter are switched off, the power meter is showing 200W more thanusual. If I measure the power consumption of the inverter directly on the socket which is connected with a socketmains power meter, it shows around 10 watts, not 200 watts. But it also shows a power factor of 0.05!When the loads are switched back on the power factor goes up to 0.6Is this normal?What is the impact of the extra 200 watts shown on the Owl power meter?0.05 power factor?Thanks.

author: bdunham7
author_rank: Super Contributor
timestamp: May 13, 2023, 05:21:23 am
content: Your OWL power meter is measuring VA (even if it doesn't display that way) and your other meter is measuring watts correctly. I'll assume the OWL doesn't show you the power factor.200VA x 0.05PF => 10W. This is due to the inverter representing a capacitive load when it is dormant, this is fairly common and not a problem. In other words there is about 0.85A of reactive current in the circuit with small losses that add up to 10 watts dissipated.

author: hgg
author_rank: Frequent Contributor
timestamp: May 13, 2023, 05:29:40 am
content: Thanks. Yes, the Owl power meter does not show power factor.So, I shouldn't freak out when the Owl shows 200 Watts more?... :-)I've heard that with some companies you pay a fine for low power factor.So, I have to find a power meter similar to the Owl that displays true power correctly.By the way, do you know if there is a way to correct that low power factorthe inverter is presenting to the grid?

author: bdunham7
author_rank: Super Contributor
timestamp: May 13, 2023, 05:48:48 am
content: Quote from: hgg on May 13, 2023, 05:29:40 amI doubt the power company is going to worry about such a small issue, especially since most low power factors result from lagging current (inductive loads) or harmonic distortion (non-PFC SMPS), not leading current from capacitors. In fact, power companies use banks of capacitors and other things to compensate for lagging currents, so you're helping a bit.Don't worry about correcting it, as soon as you turn on any of your other loads you probably swing it back the other way and the inverter's capacitor is actually increasing the PF.

author: hgg
author_rank: Frequent Contributor
timestamp: May 13, 2023, 05:50:15 am
content: Just found the following on the OWL website helpdesk:"Phantom Power" removal - Overnight generationOWL Help Centre Agent 312 January 2022 06:07"Phantom Power" is a "feature" of all PV Inverters. This is where it appears to an electricity monitoring device that the solar power is being generated even when it is dark!This Phantom Power is actually reactive power and does not register on the electricity meter. Unfortunately current clamp sensor technology that we (and others) use does not allow us to differentiate between reactive and real power, and hence the Phantom Power is detected in the same way as the true generated power is.So, this power meter cannot measure real power.The strange thing is that my previous inverter, the MPPSolar 2.4kW hybrid, did not register any phantom powerwith or without any loads while working on-grid. How is this possible?

author: barshatriplee
author_rank: Regular Contributor
timestamp: May 13, 2023, 08:05:36 am
content: Power factor of 0.05 is very low. Maybe there was a problem at the time of installation or calibration.

author: hgg
author_rank: Frequent Contributor
timestamp: May 13, 2023, 08:09:28 am
content: It cannot be calibrated. What kind of problem do you mean?

author: bdunham7
author_rank: Super Contributor
timestamp: May 13, 2023, 01:48:57 pm
content: Quote from: hgg on May 13, 2023, 05:50:15 amApparently it isn't measuring power at all, just current.Your previous unit may have had a relay to disconnect it entirely when it was dormant or it may have had a much smaller output capacitance.

author: Marco
author_rank: Super Contributor
timestamp: May 13, 2023, 02:14:26 pm
content: Why don't they just add a mains plug to the OWL? Read the phase and amplitude from the plug and the current from the clamp.

author: hgg
author_rank: Frequent Contributor
timestamp: May 13, 2023, 02:53:05 pm
content: Quote from: bdunham7 on May 13, 2023, 01:48:57 pmAnd the new one costs 3 times more...

author: hgg
author_rank: Frequent Contributor
timestamp: May 13, 2023, 02:57:16 pm
content: Quote from: Marco on May 13, 2023, 02:14:26 pmIndeed.The thing is, that the Owl is measuring the actual current that is flowing in the wire.How is this phantom power, since there is actual current in the wire?Where does this current gets dissipated? Which device consumes it?

author: Marco
author_rank: Super Contributor
timestamp: May 21, 2023, 07:54:12 pm
content: Some capacitors are storing and returning it.

author: hgg
author_rank: Frequent Contributor
timestamp: May 22, 2023, 01:53:25 am
content: So, is it energy that is going back and forth at each cycle between the inverter and theelectricity supplier?If that is so, then it will slowly be converted into heat by the resistance of the cables andat the end someone has to pay for that...

author: bdunham7
author_rank: Super Contributor
timestamp: May 22, 2023, 03:40:07 am
content: Quote from: hgg on May 22, 2023, 01:53:25 amTrue, and the current multiplied by the voltage drop in the cable give you the real component of the power. To the extent that power is dissipated in your house after the meter, you pay for it. The cost of the part that is dissipated by the utility equipment before the meter is typically not recovered by the utility unless your service is large enough that they assess you additional fees based on power factor.

author: alligatorblues
author_rank: Regular Contributor
timestamp: May 22, 2023, 04:45:00 am
content: I think the smart utility meters take power factor into consideration, and add it to the power used. I've learned an important lesson: there are excellent ways to save money on electricity, but solar-electric power isn't one of them. California has a 1 megawatt solar cell generator that cost a billion dollars. You can build a 15MW nuclear plant for that.

author: hgg
author_rank: Frequent Contributor
timestamp: May 22, 2023, 04:52:34 am
content: Luckily we do not have yet smart meters but they are on the way..I think I will wire a timer relay to switch off the grid AC input to the inverter during the night.

author: johansen
author_rank: Super Contributor
timestamp: May 22, 2023, 05:25:58 am
content: The smart meters that have a rotating disk have a 2 pole flag on the disk and a quadrature encoder to count the turns.As for 200va and 10 watts.. thats a 10uf capacitor. Or two 4.7 watt capacitors plus 10 watts of losses.Residential meters dont count kva, only kwh. And of one "large general service" that i know of in washington.. thr kva demand charge is like 100$ a month on a plant with a 40kusd a month bill. I worked the numbers out, the utility is charging the customer approximately.. exactly, the expected lifecycle costs of capacitors to offset the load.That may not be the case in california.

author: hgg
author_rank: Frequent Contributor
timestamp: May 22, 2023, 05:29:04 am
content: "As for 200va and 10 watts.. thats a 10uf capacitor. "How do you calculate that?

author: johansen
author_rank: Super Contributor
timestamp: May 22, 2023, 05:34:31 am
content: Quote from: hgg on May 22, 2023, 05:29:04 am1 over 2 pi frequency farads is capacitive reactance2 times pi times 60hz is 377. Reciprocal of that is .00265As such a 10uf cap pulls 1 amp at 265vac at 60hz.

author: Marco
author_rank: Super Contributor
timestamp: May 22, 2023, 06:19:41 am
content: Quote from: alligatorblues on May 22, 2023, 04:45:00 amYou can also build 600 MW peak utility scale PV for that.

author: 240RS
author_rank: Regular Contributor
timestamp: May 22, 2023, 06:28:00 am
content: Quote from: hgg on May 22, 2023, 01:53:25 amDepends. If there is 200var inductive reactive power (Q) in your house, the energy will not travel back and forth the the supplier at all. It will cycle in your home. If you do not have inductive reactie Q yourself, somebody in your street will. And it then cancels out.I would say, no worries, it is just a line filter.

author: hgg
author_rank: Frequent Contributor
timestamp: May 22, 2023, 06:40:55 am
content: One think I do not understand is that when I switch on the loads (PC, TV & stereo amp) for a total of around 400 watts, then the power factor measured directly at the inverter grid input climbs to 0.6With no loads it drops down to 0.05

author: Siwastaja
author_rank: Super Contributor
timestamp: May 22, 2023, 07:18:27 am
content: As others have said, that OWL thing is not a power meter. It's meaningless. Ignore it.

author: hgg
author_rank: Frequent Contributor
timestamp: May 22, 2023, 07:31:26 am
content: The power factor was measured directly at the inverter AC input.Nothing to do with the OWL meter.

author: Siwastaja
author_rank: Super Contributor
timestamp: May 22, 2023, 08:00:58 am
content: Poor power factor at low loads is completely normal. Power factor itself is not meaningful. Showing real and reactive power in Watts directly would be more intuitive, than their ratio. Imagine a situation with 0.00000000000000000000000000001W of reactive power. Is it a problem? Yet if real power is 0.0000000000000000000000000000001W, calculated power factor is just 0.01, giving an impression of something being wrong.

author: hgg
author_rank: Frequent Contributor
timestamp: May 22, 2023, 08:04:25 am
content: 10 watts active power with PF 0.05The extra 200 Watts of reactive power is real though because its been measured with a current clamp.The question is why the power factor measured at the inverter AC input goes down to 0.05 with no loadsand climbs up to 0.5 with a load of 400 watt.

author: Siwastaja
author_rank: Super Contributor
timestamp: May 22, 2023, 08:09:22 am
content: So 10W is going back and forth in the power system. As the power transmission efficiency is something like 99.9%, moving 10W back and forth is not a big issue. How far it exactly goes is hard to say, depending on other loads at your house, neighbors, and compensation networks installed... somewhere.Now if each lightbulb caused 10W of reactive power that would besomesort of a problem.

author: hgg
author_rank: Frequent Contributor
timestamp: May 22, 2023, 08:13:53 am
content: 200 watts are moving back and forth which are measured by the OWL meter that measures Apparent power.

author: Siwastaja
author_rank: Super Contributor
timestamp: May 22, 2023, 08:16:04 am
content: Yeah, sorry. It's quite something, but why do you think it matters?

author: hgg
author_rank: Frequent Contributor
timestamp: May 22, 2023, 08:19:24 am
content: I am curious to know how this inverter actually works.Why such a low PF when you remove the loads?My previous inverter which was an MPPSolar, at 1/3 of the price of the Phocos did not do that.Although it was much noisy than the Phocos, it looks like that it was working more efficiently.

author: David Hess
author_rank: Super Contributor
timestamp: May 22, 2023, 12:46:52 pm
content: Quote from: bdunham7 on May 13, 2023, 05:21:23 amQuote from: hgg on May 13, 2023, 04:51:21 amWhich is typical of a rectifier/capacitor input, so there is no mystery here and everything is as expected, although I would have expected a such a large electronic load to have active power factor correction. My big on-line UPSes do.

author: bdunham7
author_rank: Super Contributor
timestamp: May 22, 2023, 01:46:02 pm
content: Quote from: hgg on May 22, 2023, 07:31:26 amCan you describe that setup and measurement in detail? Is the inverter on or off, and if on how much power is it producing? And exactly how how are you measuring the PF "at the inverter" and are you also measuring voltage and current?

author: hgg
author_rank: Frequent Contributor
timestamp: May 22, 2023, 02:54:32 pm
content: 3kW Hybrid Inverter output always on.Batteries are empty and the inverter works as an AC grid pass through.The load is a PC+TV+Stereo Amp (400 Watts) and its either on or off.There are two power meters. One measures the power consumption of the whole house using current clampsand the other measures power consumption directly at the outlet that the inverter is plugged in. The first canonly measure Apparent Power and the second can measure Active Power and Power factor.When the loads are off, the house power meter shows an extra 200 watts of apparent power. (the reactive power)At the same time the inverter power meter shows 10 watts and a power factor of 0.05When the loads are on, the inverter power meter is showing the true Active power and a power factor of 0.5At the same time the house power meter is showing a slightly higher value than the true Active Power.