Wednesday, July 3, 2024

Reducing RFI from solar systems

  Reading this very useful and detailed post from fellow blogger KA7OEI. 

https://ka7oei.blogspot.com/2024/06/reducing-qrm-interference-from-renogy.html

I extended my solar energy production with 5 extra solarpanels a while ago. It really was a bargain getting these as I bought the 260Wp panels at a cost of €50 (€10 per panel) from a colleague. The inverter was searched for on the dutch internet marketplace and I bought one for another €50. Most of the costs were the mounting rails, wiring and the #31 ferrite to make shure no RFI would reach my antennas. The last items were an additional €300. 


The open line of the inverted-V doublet is just about 1,5 meter above the solarpanels. I even got a quarter wave CB antenna near the panels to listen to some chats on CB when in the garage. I really did take all precautions to make shure I would not have any RF coming from the inverter or the panels. On the pic at the right you see that I used big #31 FT240 ferrite rings in both AC and DC lines. The earth wire is fitted with a big #31 snap-on ferrite. DC wires are mostly fitted in earthed Alu tubes were possible. Everything is earthed to a central earth point, the tubes, the mounting frames and the inverter.

At the left a pic from the Alu tubing used. Yes, it is made of old antenna left overs. I always use what I have at hand. I seldom throw away scrap Alu tubing. Over the years I collected some ;-).

Well to keep a long story short I can recommend the page from FerriteShop about this subject. I followed most from their tips and used #31 snap-on ferrites below the panels. The only difference at my installation are the FT240 ferrite rings below the inverter.

https://ferrite-shop.com/prevent-solar-panel-interference/?v=796834e7a283

For Dutch readers it could be interesting to read the Dutch Telecom recommendation:

https://www.rdi.nl/onderwerpen/tips/voorkom-storingen-door-zonnepanelen

Well, I don't have any RFI from my own solarsystems. I see QRM in the waterfall of my IC-7300 from my neighbours solarsystem on 50MHz. Just to be shure it isn't my own I checked when I switch my own systems off. Of course there was no change, the QRM stays there and is not from my property for shure. Luckily the QRM is only there when I turn my beam over their house.


The 5 solarpanels harvested 165 KWh in less then 2 months. Approx 3 Kwh average per day. It is not much but anything helps. The system can be extended easily when I find another 5 or 6 secondhand solarpanels.

Update 20-07-2024: 

Found another batch of solarpanels. 3x 265W and 3x255W panels have been installed. The system gives me now approx 6 KWh per day. 


The investment was another €300 in total. Considering what you pay if you let a company do the complete installation this is a real bargain. I'm curious how long it takes to get to a break-even point. With my calculation I estimate a 1000KWh per year. In that case it will take about 3 years with the current electricity price. I consider an upgrade with batteries after those 3 years.


3 comments:

Jan, OZ9QV said...

I am also starting with getting more solar, and yes, I do have a bit of noise from my MPPT charge controller, and I will try more ferrite stuff on the lines.

Vy 73 de OZ9QV, Jan

PE4BAS, Bas said...

Hello Jan, If there was no possibility to do something about the RFI caused by those inverters I would never consider any solarsystem. The nice thing these days is that the panels are ridiculous cheap new and even cheaper when bought used. The challenge for me now is to buy panels as cheap as possible. I have room for another 5-6 panels.

73, Bas

PA2RF said...

Interessant en nuttig verhaal !