Lifting the hood on PV immersion controllers

A solution is now at hand for installers looking to offer their customers an ideal install, says Zuber Vindhani of PV self-consumption and control system provider Greenologic.

Businesses and consumers are quickly beginning to realise that the true value of solar PV lies in the long-term energy cost savings they can deliver rather than just the benefits from the government incentives.  This will become increasingly more evident as, over time, incentives will become smaller and energy costs will grow. Together with the introduction of state-of-the art energy management systems and storage options now available, installers can offer an enhanced solar PV install that will generate tangible energy savings and future-proofing energy supply in addition to the financial rewards from micro-generation.

Cost effective energy storage has been considered the key to ensure the viability of solar PV for the long term and the market has seen a number of devices that can divert surplus energy to heat storage, such as an immersion tank.  And whilst this is now seen as the way forward, the other key component for the ideal install is to address the technical aspects of power modulation to a resistive load, such an immersion heater.  According to Greenologic, the UK’s leading provider of PV self-consumption and control systems, a solution is now at hand from specialist control systems manufacturer, 4-noks.

4-noks has now launched the Power Reducer for immersion control with solar PV that eliminates many of the issues that have troubled current products in today’s marketplace.  As an example, achieving full CE certification, rather than self-certification, was a primary objective for the 4-noks engineering team.  Also included in the design brief was to build in compatibility with the new breed of digital/smart meters, due to the difference in sampling rate in which energy is recorded from the grid.

One of the key issues with many solar PV control products is the type of modulation they employ to alter the AC sine wave, so that the energy diverted to an appliance can be ‘proportionally controlled’ so as to use only surplus available energy.

The three mainstream methods of modulation have been categorized as; Burst Fire, Phase Angle and Pulse-Width Modulation (PWM). In-depth analysis into these technologies has revealed a number of issues that have all been addressed in the design and specification of the Power Reducer. Studies by 4-noks have shown both Phase Angle and Burst Fire technologies to be inadequate in achieving full CE compliancy for specific regulations and norms due to the generation and leakage of harmful EMC emissions – causing concerns both visually in ‘flickering’ and behind the scenes on grid side with DNO supplier.

However, and after rigorous testing, PWM was found to be the most adequate solution in the ability to alter the energy diverted to the load whilst causing the least strain on the AC sine wave. With the inclusion of specific filter or ‘super filters’ within the Power Reducer, harmonic emissions can be contained to acceptable levels – enabling the solution to meet the stringent CE and EMC compliancy for the domestic class:

EMC (Electro Magnetic Compliance)

EN 55014-1: Electromagnetic compatibility – Requirements for household appliances, electric tools and similar apparatus – Part 1: Emission;

EN 55014-2: Electromagnetic compatibility – Requirements for household appliances, electric tools and similar apparatus – Part 2: Immunity – Product family standard;

LVD (Low Voltage Directive)

EN 60335-1: Household and similar electrical appliances – Safety – Part 1: General requirements;

EN 60335-2-21: Household and similar electrical appliances – Safety – Part 2-21: Particular requirements for storage water heaters;

The Power Reducer will be available in the UK early September 2013 and will also benefit from the value-adding features of Elios4you – a self-consumption platform using a smart device such as a smartphone or tablet.  Elios4you features a host of energy reporting tools delivered in real-time to make use of additional surplus energy and manage overall consumption which can eliminate estimated billing; this ultimately achieves even further savings on the overall energy bill.