Monday, September 25, 2023

Power from the sun causing QRM?

   Does power generating with solarpanels cause QRM? Yes and no. The strange thing is that some solar power installations/systems do radiate noise while others seem not. And of course it is not the actual solarpanel that radiates but the solarcharger, inverter and wiring do if not filtered and earthed well. Besides that many installations use so called optimizers which are known for causing a lot of noise. I will not write about the cause of this all. Only about my own experiences and the things I did to prevent QRM/noise from a solar generating installation at my own home.

Buying a solar system

The dutch goverment wants to have as much "green" energy as possible of course, it will be the same in other countries I guess. To support home owners to buy solar installations for private use we can now buy these VAT free. And of course if you're able to install these yourself it is possible to buy a reasonable installation for about 2000 euro. With the current and rising electricity prices and the increasing amount of electrical things at home this is of course very interesting. I really don't care about the impact on the environment in which I do not believe. See my post here: So we decided to order an installion of 8 solarpanels which we thought to mount on top of our glasshouse. 


Because I wanted to do all installation myself it was a great opportunity to see what I could do to prevent QRM. The inverter is placed behind the wall of the glasshouse on just about 10m from my antennas. I already have much noise from neighbours surrounding solarpanels (they use optimizers) so I really didn't want to have a increased noise from my own installation.

The first challenge was how to mount the panels on the glass. Normally solarpanels are mounted on a roof with tiles. I invented simple aluminium frames on which I could mount the aluminium  mounting rails that were supplied with the panels. I could mount 4 panels per frame. The total weight of one frame with panels would be approx. 100kg. The next challenge was how to mount everything on the glasshouse without breaking the glass. The idea: place the frames on the lower end of the "roof", mount the panels on the lowest rail and hoist the frame up the "roof" with ropes. Luckely the glasshouse consists of aluminium profiles which hold the glass plates sealed with a kind of rubber strip on top. The frames could slide over the rubber strip without breaking the glass. Well, in the end I managed to break four glass plates, but they were easily replaced. Luckely I was able to hoist the frames myself. The frames are secured on top of the brick wall. The lower end of the frames is not yet secured, I have to invent something for that since I cannot secure it to rubber, glass or the aluminium profiles.

Preventing QRM/noise

Time to install the wiring. Of course I already got information how prevent radiation from the system as good as possible. The things I did:

- Prevent a loop with the DC cable. The panels are connected in series. The positive and negative wire are running back as close as possible to the connecting wires in between the panels.

Alu duct running up the wall

- The positive and negative DC wires are running through the center of the 8 panels in between the two frames up to the wall. I mounted the inverter on the other side of the wall. I twisted the wires the whole length to the inverter.

- Where possible I run the twisted DC cable through aluminium earthed ducts. Both frames and  the solarpanel(frames) are earthed to the mains earth.

Large ferrites

- Ferrite material #31 clamps are placed on the start of the positive and negative returning DC cables. Ferrite clamps also placed at the point were cables are going up and on top of the wall.

- Ferrite FT240 #31 torroids placed just below the inverter at the DC wires and the AC cable.

So far I didn't notice any increase of noise on any of our hamradio bands. 

For free

Free energy from the sun. Like it or not but it seems to work well. And it is possible to have it without QRM/noise if you ensure a good installation.

Unfortunately we didn't have much sun last week. But at least 27 kWh in just 6 days. Enough to run at least my radios/computers for free.


John AE5X said...

Very interesting, Bas - congrats on the installation. How many watts worth of panels do you have? We are thinking of doing the same thing here...unfortunately, our house is not oriented so that the slope of the roof faces south, when we would get peak power. How did the battery installation go?


PE4BAS, Bas said...

Hello John,
Panels are 370W x8 =max. 2960W. But overall it will be 70-90% max. of this normally. There is no battery, the system is directly connected to the grid. In the Netherlands it is still common this way since the extra power you deliver to the grid is substracted from the power you use. Investment in a battery would be too expensive at this moment. However, electricity companies are complaining the extra energy is overloading the grid and all this extra power will cost them and customers without solarsystems money. So thing will change in the next years. I'm thinking about a battery system now that I charge over the day and that can deliver for instance power for lightning and my shack during the evening. Anyway, the system works well the last days (lots of sun), it is generating more power as our consumption this week. 73, Bas

MadDogMcQ said...

Wow, that’s quite a big project! Well done Bas. It would be useless in the NW UK because it just rains every day LOL.

73, Tom, M7MCQ.

PE4BAS, Bas said...

Hello Tom, even when it rains the system still delivers power. But peaks are when the sun shines of course. We don't have much sun either at the moment. I'm surprised though the system works that well. 73, Bas