Standard deviation


Jodi Huggett, innovation director at 4eco, asks if meeting electromagnetic compatibility standards (EMC) is one step too far for the renewables industry.

Recent figures from DECC show that over 80,000 solar PV systems were installed across the country between January and August of this year.

To make the most of this trend and increase the potential of renewable consumption, eco businesses nationwide have dedicated significant resource into developing innovative cleantech products – to increase the efficiency of energy generation.

Delivering consumer benefits
There is now a proliferation of microgeneration power diverters that are sold throughout the UK and Europe.

Power diverters help end-users self-consume the green energy that is produced by their microgeneration system. These devices monitor power being exported to the grid and divert this surplus power to a designated load, normally an immersion heater.

Whether in a domestic or small scale commercial scenario, up to 100% of self-generated power can be consumed. This helps to reduce reliance on the grid, reduce energy costs and reduce individual carbon footprints.

The latest insight from UK installers has identified that over 50 percent of new solar PV installations include such devices – meaning that, this year alone, around 50,000 devices have been installed as part of new microgen set-ups.

Fit for purpose?
To say that all microgen power diversion technologies are comparable is simply not true. These devices vary significantly in performance, efficiency and durability.

The market currently plays host to over a dozen different devices – all claiming to deliver the same results. This, unfortunately, is not the case. In fact, as the development of many of these devices has been rushed to meet market demand, a high percentage fail to meet the EMC standard for harmonic emissions. Many of the 50,000 devices installed so far this year, do not comply.

The immerSUN®’s truSINE® power control technology diverts self-generated renewable energy to its destination. This technology employs pulse width modulation (PWM) which ensures the power is delivered to the load as a true sine wave. This highly effective control method means the immerSUN® complies with all applicable parts of the EMC directive 2004/108/EC, including EN 61000-3-2 – the harmonized standard for regulating levels of harmonic emissions.

Phase angle control
The same cannot be said for all devices, however. Of the fifteen known systems currently on the market, only three use PWM. The others use an alternative energy management technology called ‘phase angle control’.

Phase angle control devices do not produce a true sine wave. Instead, the waveform is severely distorted, creating vast amounts of harmonic emissions. This practice can cause problems with the inverter and other electrical equipment, including premature degradation of the heater element. Such harmonic interference is also conducted through the cabling, resulting in possible overheating, and can affect neighbouring properties as well as being transmitted back to the grid.

Devices which use phase angle as their power control method will exceed the levels for harmonic emissions and will not comply with the EN 61000-3-2 standard. As such, these devices cannot be CE marked and freely sold throughout the UK and Europe.

As a result, 80% of the microgen power diverters currently available to purchase in the UK are not legally compliant – an incredibly worrying statistic.

No hiding place

“Regulations require all electrical and electronic equipment apparatus in the UK, including imports, satisfy the requirements of the EMC Directive.”
The EMC Regulations 2006, source: www.gov.uk

Although the importance of appliance safety should be prioritised in all new product development and production, compliance policing is not always effectively implemented across the UK. As the burden of CE testing falls on manufacturers themselves, many choose to self-test their products in-house rather than via an authorised body.

Electrical and electronic apparatus has to be designed so as to pass the relevant EMC and safety standards. This cannot just be an afterthought.

Third-party testing by a notified body is not compulsory. Irrespective of the chosen route (in-house or authorised), the manufacturer has full control of how their product is tested, in order to attain the required standard. This can lead to the manipulation of testing parameters, so as to corrupt the validity of the result.

Trading Standards is the Market Surveillance Authority in the UK for EMC. One must ask themselves, is there likely to be the specific knowledge of EMC, together with sufficient manpower to effectively police compliance?

Levelling the playing field
Consumers need to be safe in the understanding that each and every product that they purchase is safe for use and free from dangerous side effects – something which the renewables industry is currently not achieving. There is undoubtedly a great deal of government support for renewable technology, but there does not seem to be the same interest in the effective monitoring of compliance.

Maybe then, the responsibility lies with the wider industry itself? Certainly the MCS operators have a vested interest in the compliance of these devices, as all inverters have to pass the very same harmonic emissions tests that these products are failing. Unless we can effectively address this situation, then non-compliant products will continue to be installed into homes and businesses across the UK and Europe.