[RFI] Solar Inverter.

[Neil & Heather]

Dale,

First,Thank you for a very detailed email.
I will be doing the install of the filters,as the
reason he called me is I am a Master Electrician, and the City requires
any work done on his system to be done by an Electrician.
For me personally,this is the first I have had in dealing with any Solar 
Systems,as I mostly do new Commercial construction, and
now Maintenance for the City of Keene,hence,the reason why I posted to 
this list..
As I knew there would be those that could offer great assistance.
I will pass on your thought on why the original installer
isn't being held responsible,
and also ask him if he wouldn't mind giving You his email,as it might be 
nice for the two of you to discuss his system,
as I haven't even seen it yet.(If you wouldn't mind,also)
Again, thank you for your assistance..and I am still trying to get some
feedback on those particular EMI filters.

73
Neil
AE1P

p.s.  Thank you Tim for your help..getting this to the list.

On 3/19/2012 11:49 PM, Dale Svetanoff wrote:
> Neil,
>
> Considering the cost of cleaning up "dirty" inverters, my first thought is
> to ask your local ham friend if he had stipulated anything in the contract
> with the solar system provider to make them responsible for not interfering
> with his radio operation.  If he did not, he may be in for a very expensive
> cure to the problem.
>
> As in any RFI situation, you have a source (which appears to be the
> inverter) and a victim (the antenna(s) feeding his radio receivers).  The
> first thing to do would be to determine the coupling mechanism, as in is it
> via the low voltage/high current input wiring of the inverter or via the
> 120/240 VAC house wiring that is attached to the output.  One way to do
> that would be to place a dummy load (lots of incandescent light bulbs) on
> the output side of the inverter with the leads to the house wiring
> disconnected, and then power up the inverter.  If the noise is gone or
> reduced, then he knows that the house wiring is a major part of the
> coupling mechanism and filters on the inverter output should be beneficial.
> If the noise level hardly changes, then it would seem to be the input
> wiring to be the culprit.  In reality, I expect that both wiring systems
> may be radiating.
>
> I am not familiar with this particular brand of power filters, but they do
> appear to be "real" industrial grade filters.  Having worked for more than
> 13 years at a company that had a filter product line similar to these, I
> can tell you that yes, they will be pricey.  Do not be surprised if the
> filter costs exceed $1500 or more.  At that price point, it may be worth
> looking at what else could be done.  One suggestion is to increase the
> distance between source and victim - in this case, get the antennas further
> away from the house.  It may be necessary to move them by several hundred
> feet or to re-orient their position relative to the house and its wiring.
> Another suggestion, of course, is to open up the inverter to see how it is
> wired and constructed, and then plan a method of applying internal chokes
> and by-pass capacitors to knock down the offending hash.  Of course, this
> path is liable to void any warranty on the unit.
>
> Remember, the best cure for reducing RFI from a specific source is to
> reduce or eliminate the emissions either within the source itself or as
> close to the source device as possible.  So, if he ends up buying the
> filters, he needs to install then directly adjacent to the inverter and
> connected with the shortest possible leads.  He must also ensure that there
> is a proper, low impedance ground path between the filter case and the
> inverter case (assuming metal cases).  Note that while the inverter should
> be grounded to meet codes and for safety, that grounding path is likely to
> be long.  No matter, because we are talking common mode radiated emissions,
> what matters most is the path between filter and inverter because that is
> where the circulating currents will be located.
>
> Finally, an obvious question:  Is the inverter in a metal case or chassis?
> One would hope so.  If not, it needs to be.
>
> I really hope that your friend can throw this whole mess back at the
> installer or equipment manufacturer, where it belongs.  I hope I am wrong,
> but this could become a very costly fix.
>
> 73, Dale
> WA9ENA
> Sr. EMC Engineer
>
>