A plug-in solar PV system for the balcony can be bought in many shops. In Denmark it must not be connected with a plug in an ordinary socket-outlet. Here are the three risks that the Danish Business Authority (formerly the Danish Safety Technology Authority) points to, and the legal way to connect the system.
Introduction
A plug-in solar PV system is a small system with one or two panels and a microinverter. It is intended for a balcony, a carport or a garden wall. The output is typically from a few hundred watts up to approx. 800 W per system. The system is sold with a cable and a plug, so it looks as if you can just plug it into a socket-outlet. That is not allowed in Denmark. HD 60364-5-551, item 551.7.2, makes it clear that connection via plug and socket-outlet is not an option.
Why the plug is the problem
The guidance on sik.dk mentions three risks:
- 01Overloading of older installations. It can cause heat and fire.
- 02Electric shock from the plug's pins. When the plug is pulled out, the pins can be live from the panels.
- 03Voltage back in the installation. When the grid is disconnected, the system can still send voltage into the dwelling's installation — also to the person who thinks it is switched off.
How it can be made legal
The system must be permanently connected and run to the distribution board. There it is connected on the supply side of the fault and overcurrent protection, as a generating set. The work must be carried out by an authorised electrician.
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