[RE-wrenches] Enphase data interference

[Larry Crutcher, Starlight Solar Power Systems]

Yes, this type of common and normal mode filtering will actually perform better as frequency increases due to decreased impedance of the capacitor. 144 kHz is actually low and most likely radiating through the AC mains. If this is so, it is good news as  its generally easier to filter. Above 30 mHz or so you can expect the RFI to be radiated and interference is received like a radio station signal.

See attached picture for more clarity on cap installation.

Larry Crutcher
Starlight Solar Power Systems


On Sep 25, 2012, at 3:33 PM, William Miller wrote:

Larry:

Thanks very much.  I am gong to do what you recommend.  By the way, the interference is said to be at about 144kHz.  Do these cap values seem to be relevant at that frequency?

WM

At 01:31 PM 9/25/2012, you wrote:
> Hello William,
> 
> Since you have identified the cause, look to filtering the RFI at the source, it will be easier than trying to keep it out of your Envoy. I would start with AC line capacitors. Solder a 0.1uF ceramic cap from leg~leg and leg~ground as close to the motor as you can, keeping leads short. Do the same at the AC input and output to the motor controller if it has one. Make sure the motor frame has a good ground. If possible, make sure that your PV system, monitor and the pond motor are at the same ground potential.
> 
> Note: If a line voltage surge occurs, these caps will likely burn or explode (small scale) so, with this in mind, be aware of placement.
> 
> I can tell you from many years experience as an amateur radio weak signal operator, detection and reducing RFI issues are a mix of science and art. You may want to contact your local Ham Radio club and see if they can recommend someone that is willing to help.  Good luck!
> 
> Larry Crutcher
> Starlight Solar Power Systems
> 
> 
> 
> 
> On Sep 24, 2012, at 5:47 PM, William Miller wrote:
> 
> Friends:
> 
> Just a heads up for those of you installing Enphase systems:
> 
> After installing over a dozen systems we came up with a job where we have been unable to resolve interference issues.  The problem is receiving data from the inverters into the Envoy.  We have tried relocating every component, using multiples of the ferrite beads, various models of X10 filter modules, etc.
> 
> Enphase has been trying their best, remotely, to help resolve the problem but without success.  The interference is being caused by an expensive pond pump (or we would have a new one by now).  We are awaiting an AC filter module from Digi-key.  I will let you all know how it turns out.
> 
> In the meantime, I have added the following paragraph to my contracts:
> 
>         Data systems: Some new inverter systems transmit data over your power lines.  On rare occasion interference from your appliances will occur that block this data transmission.  We can resolve these problems but there may be extra charge for our time and materials.
> 
> My profit from this job has evaporated.  I am writing this because I don't want to see any of you in this situation unknowingly.
> 
> More later,
> 
> William Miller
> 
> Miller Solar
> Voice :805-438-5600
> email: william at millersolar.com
> http://millersolar.com
> License No. C-10-773985
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