On Oct 1, 1:27 pm, Jeff Liebermann wrote:
"hr(bob) " hath wroth:
Are the invertors for the solar systems meeting the FCC Part 15 rules
on emissions??
H. R. (Bob) Hofmann
The few I field tested locally obviously did not. I do not have the
full antenna kit necessary to make the determination. However, my
back of the envelope calculations based on received signal strength to
a small loop antenna seems to indicate that it's not even close. I
need to drag over a spectrum analyzer and see what's really being
radiated. I built a small power line coupling circuit so that I can
look at the AC power waveform. I could see roughly 200mv switching
hash on an oscilloscope so I suspect that this system wasn't
compliant.
The owner of one private solar system is working with the manufactory
on reducing the interference and has installed power line EMI filters.
These were a huge help. These filters are allegedly standard on all
their current installations but were not when he purchased his[1]. A
different owner just received what I suspect may be the worlds biggest
clamp-on ferrite bead. He says it's about the size and weight of a
brick and goes on the solar panel leads. That was installed about a
month ago, and helped somewhat.
Meanwhile, the ham operators that have been affected are making
measurements, running tests, and playing with different types of
antennas. There's been some success. Weak signal DX is out, but
contesting, RTTY, PSK31, and other modes operate normally. At this
point, radio reception is functional and not a crisis.
The big problem is that almost all the EMI is being conducted (and
radiated) through the power lines. We can turn off one source of
switching noise, and there's very little effect as the other noise
sources are just as strong over the shared power lines. At one point,
we obtained the cooperation of everyone involved, except the water
district, to turn off their solar systems completely for an hour so we
can make measurements. We then found yet another solar system noise
source we had not known about and possibly two more. We also
determined that the major source of EMI was the water district system.
At this point, we know of about 7 solar systems within about a 1 mile
radius. Most of them were found by sniffing, but others by accident
or with an airplane flyover. We tried Google Earth, but the images
are too old. What was interesting is that many of the solar systems
we found were fairly RF quiet, while others were very noisy. The
difference seems to be the amount of EMI/RFI filtering on the various
wires going in and out. The quiet ones are liberally equipped with
filters on the panels, AC mains, and control panels. The noisy ones
do not.
Much of the testing and sniffing has been done with portable AM radios
and a SW AM radio. The noise is continuous, very strong near the
power lines, and very obnoxious on AM. My guess(tm) is that the
original problem might be one of these solar inverter noise sources.
[1] I suspect that the installer "forgot" to install the filter or
lost it since it's a separate box and did not fit neatly into the
installation.
--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
I am assuming that you mean the invertors that change the DC from the
charged batteries to 120-240V AC, not anything associated with the
solar cells charging the batteries. Am I right?
If there are any clocks associated with the invertor control
circuitry, the entire installation falls under the FCC Part 15 Rules.
These apply to any "noise" from 150 kHz up to 30 MHZ for conducted
noise from the installation onto the power lines and you should notify
the nearest FCC Feld Office.
I am a past president of the IEEE EMC Society and am still very active
on IEEE and ANSI C63 (TM) EMC committees. Let me hear from you,
either here or directly to me.
H. R. (Bob) Hofmann