Solar near Airports [RE-wrenches]

[Bill Brooks]

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Ray,

I can't speak for John, but I think he is focused on an important issue,
that of FCC compliance for inverters. There is some disagreement in the
industry about how and what applies to differing size inverters, but the
fundamental issue is important--Inverters should be tested so that they are
not likely to cause radio frequency interference (RFI).

Being FCC compliant does not guaranty immunity from RFI problems. Right on
the FCC label it explains that if a problem exists because of this piece of
equipment, relocate antennas or move the equipment.

I currently have an installation in SoCal where we have 10 SMA SB2500U
inverters and two Xantrex PV20208 in an 8'x10' room that is literally 3'
from a very large computer server room. Many were nervous about this
installation, many questions were asked, some data was presented, but until
we flipped the switch, no one knew what would happen. The impact of high
frequency noise is seldom predictable.

In this case we had no interference problems with the adjacent equipment.
Formal tests have not been completed, but an interesting test would be to
look at the RFI produced by the 10 SB2500U versus the PV20208 inverter.

All this is to say some form of RFI testing should be required of all
inverters. Companies that show compliance with FCC regulations should be
congratulated for proving that they are compliant. It is one reference point
to consider when purchasing an inverter.

As it pertains to your question at hand, the probability that a PV-series
inverter will cause a problem at your installation is extremely small. It is
a similar probability to a dozen SB2500U causing a problem (equipment is
tested one at a time, not as a block of a dozen). As was pointed out in a
post, distance is the key. No airplane is going to get close enough to be
affected by a Xantrex or a SunnyBoy. In either case, if you cause
interference with either FCC or non-FCC compliant equipment, it is up to you
to solve the problem. The airport is not going to move their antennas for
you. Neither is Xantrex or SMA going to pay for RFI remediation. So pick the
inverter you like best and ground everything really well.

Bill.


-----Original Message-----
From: Ray Walters [mailto:ray at solarray.com]
Sent: Monday, July 19, 2004 10:00 AM
To: RE-wrenches at topica.com
Subject: Re: Solar near Airports [RE-wrenches]

Thanks all;

Looks like I dug up a good topic. First, this installation is not on
airport property, it is not a large airport, and my installation is not
subject to the scrutiny that some of your previous installations had. (This
is next door is a 30 ft two way radio transmitter for instance). So
basically Bill is saying don't put the inverter on board the aircraft, and
John is saying that every install I have done is a potential hazard to low
flying aircraft. I am very interested in this. Lets cut to the chase, which
inverters have FCC compliance, and which have serious interference
problems. Can we talk brands and models now?
Also, for watt-sun trackers, I agree with your comments William. I replaced
Watt-Sun controllers damaged from lightning many times. This site will be
under my watchful eye, so any failures will only last a day or two at most.
As for accuracy, I used these on concentrator systems that required extreme
accuracy. I've found the Watt-suns do the job right out of the box. I have
not experienced the sensor degradation problem.

Ray



>Ray:
>
>My experience with Watt-sun trackers is that they work great, when they
>work.  I've sent each controller I've installed back more than once for
>repair.  I suggest you find out independently (not from someone on the
>list wanting to promote them) if they are any more reliable these days
>than they used to be.
>
>Also, if the tracking is not completely accurate, you could be reflecting
>towards the shadow, not right at it, exacerbating the problem, right?
>
>William Miller

Ray Walters
ray at solarray.com
President, SolarRay, Inc.
NABCEP Certified Solar PV Installer
BS Mechanical Engineering, UT Austin 88
Returned US Peace Corps Volunteer

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