Avoiding Electromagnetic Pollution in Solar Photovoltaic (PV) Systems
Michel Daniek (aka Solarmichel), author of Do It Yourself 12 Volt Solar Power, explains how to avoid electronic magnetic pollution – 'electrosmog' – in an off-grid 12 volt power systems.
We know that mobile phones can cause brain tumors and that some people can't sleep well near mobile phone masts but we should also be worried by the growing number of domestic electrosmog polluters which most people use without any thought of the possibly harmful radiation. Energy saving light bulbs, cordless phones, WLAN routers, and other wireless devices are all major culprits. Electrosmog is an issue that is very difficult to get to grips with because it has so many parameters.
• Tension, headache. (Usually the range of KHz up to MHz)
• Immunodeficiency and cancer. (MHz and GHz frequencies)
Although solar panels and batteries in off grid systems generate a clean direct current. The situation is quite different with modern solar controllers, 230Volt inverters and the inverters for feeding the grid. These are the ones, which can turn a basically very harmless technology into a bad electrosmog polluter. There are technical ways to do it differently and I think the entire direction of solar development really needs to be rethought.
After the first simple 2-point controllers (on/off), came the pulsed shunt regulators that have been on the market for many years now. They feed the battery at the end of the charging cycle with small chopped pulses (50-100Hz), in order to maintain it at maximum charge. The advantage being that the battery is fully loaded as quickly and as effectively as possible. The disadvantage is that strong electromagnetic fields are also distributed via the whole cable systems (often you can hear interferences in audio devices connected on the same supply network). These electrostatic fields interfere with frequencies that are very similar to the 230V mains.
Inverters fall into the same category of electrosmog polluters. Unfortunately, they are often unavoidable unless you are able to source or rebuild all your appliances to be 12 volt, which have lower electrosmog and converting losses. Many 12 volt conversions are easy to do, such as 12 volt lighting with halogen or LED lamps and even cordless tools and most other battery devices but computers, TVs and washing machines are best used with a 230 volt inverter. The less we have to turn on the inverter the better, because our bodies respond better to short electrosmog attacks than to continuous 24-hour stress. The interference from inverters is very strong because of the large currents between battery and the inverter. Low-cost devices are the worst with high-frequencies (20-30KHz) generated on top of the trapezoid waves, which causes a lot of more interference. For the cleanest results use pure sine wave inverters with a big ring core transformer and low-frequency technology (50Hz). Not cheap but they will last a lot longer than the low-cost ones.
In terms of electrosmog the disadvantages of MPPT controllers and 230 volt inverters are combined with grid inverters, as they always make a lot of wave motions in the ether. The interference frequencies of these inverters (mostly 20-30KHz) often also bleed over into the DC circuit of the solar panels on the roof. The electrosmog is then potentially very strong because of the large size of the installations. Capacitors or mains filters can buffer the harmful electromagnetic waves but not eliminate them entirely. This problem could really only be corrected by creating a decentralized DC network, but this is something that is still a long way off.
Certainly, not all problems can be solved. Life is always full of compromises, but if we would at least try to do our best it would certainly help. I don't want to scare anyone here, because no one benefits from that, but I think a conscious level of respect for this phenomenon could not harm us at all. Choose your equipment carefully and ask your suppliers for more information about their products. If you want an electrosmog free solar controller, you will not really have much choice than to build one yourself, because amazingly you can't buy one anywhere. I have therefore developed and published a DIY regulator in my book: Do It Yourself 12 Volt Solar Power. The described solar controller uses the latest MOSFET shunt technique but with very slow switching frequencies of about 20 seconds, which makes it electrosmog free. The only drawback with it is that the last 5% of the battery capacity is only recharged quite slowly. A small loss, but it should be worth for our health. In this book you will also find a whole chapter about electrosmog, and lots of practical instructions, tips and tricks on how to measure it and also how to reduce and/or avoid it.