Well, the PV system is not the problem then. There is an additional reactive load added that just happened to be at the same time as the PV system.
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high reactive power after solar install.
- Thread starter wwstrick
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wwhitney
Senior Member
- Location
- Berkeley, CA
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- Retired
Or a metering error.Well, the PV system is not the problem then. There is an additional reactive load added that just happened to be at the same time as the PV system.
Cheers, Wayne
That’s the reason for my post (#20)Or a metering error.
Cheers, Wayne
wwhitney
Senior Member
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- Berkeley, CA
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- Retired
Yes, the scenario you outlined there is quite plausible, and the pf does get worse, but the meter shouldn't show an increase in kVar for your scenario.That’s the reason for my post (#20)
Cheers, Wayne
Possibly it will.Yes, the scenario you outlined there is quite plausible, and the pf does get worse, but the meter shouldn't show an increase in kVar for your scenario.
Cheers, Wayne
I don’t know what type of meter is there. The older meters could register vars when the voltages were shifted 90 degrees. With Watts and vars 90 deg apart their could be a metering error simply in the way the metering is set up, especially with PV added and exporting. The old meters don’t calculate Fourier Transforms easily. Old style mechanical metering would have to have four meters to register watts and vars in a bi-directional setup. It was the earliest four quadrant metering.
I would consider a metering error if this were a standard residential metering setup. Residential meters don't measure VARs since residential customers are generally not billed for peak reactive power usage or low PF as a commercial client might be. But if the existing billing system is billing for VARs then the meter will be tested and certified for measuring VARs. Generally, states are kind of careful that if customers are being billed for something that it is measured by calibrated meters. That being said, it could be that the meter, while being completely accurate at measuring load consumption, is not the correct setup for measuring back feed correctly. Some older meters would read power flow in either direction as usage and bill the customer for exported energy.Or a metering error.
Cheers, Wayne
winnie
Senior Member
- Location
- Springfield, MA, USA
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- Electric motor research
That being said, it could be that the meter, while being completely accurate at measuring load consumption, is not the correct setup for measuring back feed correctly. Some older meters would read power flow in either direction as usage and bill the customer for exported energy.
According to https://forums.mikeholt.com/threads/standard-vs-net-meter.2561707/post-2677754 so called 'secure forward' meters are currently intentionally installed (presumably to prevent people from stealing electricity by reversing the meter). If you install a PV system without a proper interconnect agreement you will be punished with a higher bill!
-Jon
ggunn
PE (Electrical), NABCEP certified
- Location
- Austin, TX, USA
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- Consulting Electrical Engineer - Photovoltaic Systems
Years ago I knew a guy who was doing that, but one month he left the meter flipped too long and the meter reader read a negative usage number. Someone from the utility came out and found where the guy I know had cut the wire right up against the tag and bent it back to make it look uncut. Oops.According to https://forums.mikeholt.com/threads/standard-vs-net-meter.2561707/post-2677754 so called 'secure forward' meters are currently intentionally installed (presumably to prevent people from stealing electricity by reversing the meter).
zbang
Senior Member
- Location
- Roughly 5346 miles from Earls Court
And my post (#11- get some actual VAR measurements).That’s the reason for my post (#20)
- Location
- Placerville, CA, USA
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- Retired PV System Designer
I could see a potential problem once the inverter is set to a non-unity PF. The utility meter is configured to accumulate inductive VARs, but might be in a "secure forward" mode in the VAR portion which would also run up the VARh total for capacitive VARs. (Thanks to H&Lv for bringing that up.)
(Still does not explain what the OP is seeing though).
I wonder if the utility might actually be calculating the penalty by applying the worst case measured PF to the real power number? And just displaying it as if it were measured kVAR.
(Still does not explain what the OP is seeing though).
I wonder if the utility might actually be calculating the penalty by applying the worst case measured PF to the real power number? And just displaying it as if it were measured kVAR.
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