Electronic systems for renewable energy sources, home automation

Basic functional description

Purpose of WATTrouter usage

The purpose of WATTrouter controllers is to optimize self-consumption of energy produced by your photovoltaic or wind power plant. Self-consumption can be maximized up to 99% according to fully programmable criterions.

With the aid of WATTrouter controllers you can utilize electricity at production time when your photovoltaic plant runs and save it at consumption time when your photovoltaic plant does not run.

Today this approach becomes more important especially in countries where feed-in tariffs get inevitably lower and lower. Second, the energy produced by photovoltaic or wind plant can almost fully be consumed locally without the need to distribute it accross distances via power grids.

WATTrouter devices are small, cheap and easy-to-fit. They meet both economic and environmental goals for each houseowner with installed PV or wind power plant. They also help to reduce overvoltage in power grids by decreasing the amount of surplus energy.

These controllers provide non electric acumulation and automated electricity utilization without the need of expensive and inefficient batteries. Heating loads, such as boilers, immersion heaters, high capacity water heaters, swimming pool heaters usually get connected to WATTrouter outputs. The same applies for air conditioners, swimming pool pumps, heat pumps and another similar loads suitable to accumulate or use electricity at production time.

Fridges, dishwashers or washing machines can be connected to WATTrouter outputs but it is not recommended. Battery chargers can be connected as well. Energy accumulated to batteries can later be used for lighting, televisions, computers.

The function of WATTrouter devices can be explained by using charts below.

Operation without WATTrouter

Without the aid of a WATTrouter device the surplus energy from your PV or wind plant flows into public grid, for ever lower feed-in tariffs and with all disadvantages for power grids if there is too many surplus energy. This example shows a boiler (water heater) which runs potentially at night. In some countries there are two electricity tariff prices - normal tariff (higher price) and time limited low tariff (lower price) which is mostly active at night. This depends on the regulations of your local electricity provider. Boilers usually run when there is cheaper electricity price - low tariff at night. In the charts HT stands for normal (high) tariff and LT stands for low tariff.

Note: Energy can be saved even if there is only one fixed tariff price (normal tariff). Heating loads need to be always exactly controlled according to the available surplus energy.

Operation with WATTrouter

With the aid of a WATTrouter device the surplus energy from your PV or wind plat flows into your electric loads (heating loads or other suitable) that can be programmatically switched on when your PV or wind plant runs. In this example the energy flows into the boiler at day time. It is precisely the amount equal to the actual surplus energy. Yes, WATTrouter can "route" almost exactly the amount of surplus energy by quickly and exactly modulating the load's power. Boiler is connected to the triac or SSR output of WATTrouter, which is capable of quasi-proportional control of the power drawn by the boiler. Energy used at night could be saved.

Note: The unused surplus energy in above example can be further used if other load is connected to WATTrouter. This example is simple and we just let the unused surplus energy flow into the grid.

How it works?

WATTrouter device always consists of 2 modules. First of them is the current sensing module, which just measures currents flowing from and into your house. Second module is the regulator which does all the controlling stuff. The regulator evalutes measured currents and according to sampled voltage calculates the power and its direction (production or consumption). If production is detected built in outputs in the regulator turn on according to programmed priority schemes. Within any programmed scheme the regulator always tries to maintain zero energy flow through current sensing module and thus your main electricity meter. Regulator can be programmed to hold "virtual zero flow" (sum of active powers of all three phases = 0) or physically zero flow in either phase wire ("phase zero"). The control mode must be correctly selected according to the mode of your main electricity meter.

Switching mechanism according to priorities:

In standby state (at night for example) all connected outputs / loads are off. In the morning, when the PV plant begins to generate electricity the first (highest) priority load is switched on.

The switching point differs for output types.

Triac and SSR outputs switch on instantly when production is detected and the regulator maintains virtual or phase zero by using special quasi-proportional control mechanism. That's why there can be only pure heating loads connected to those outputs.

Relay outputs switch on when the surplus energy exceeds the connected load's nominal power value.

When a connected load with the first priority is fully switched on the regulator waits for the production to rise (sun is rising to zenith). When it detects further surplus energy second priority output will be switched on in the same manner as the first priority output.

And again when both outputs/loads are fully switched on and further surplus energy is detected then lower priority outputs and connected loads will be switched on.

If the production generated by PV plant suddenly falls or an unmanaged load (electric device not connected to WATTrouter outputs) is swiched on, WATTrouter swiches off respective outputs in the reverse order (first the lowest priority outputs will be switched off and then the higher ones).

If the load connected to some WATTrouter output gets disconnected for some reason (thermal fuse, water is too hot etc.) the regulator instantly switches on lower priority outputs.

For relay outputs there can be on and off delays programmed. This applies for electric loads where frequent swiching is quite bad (motors, pumps etc.). If there is a triac or SSR output switched on with higher priority and the PV production falls, then in such cases the regulator automatically decreases actual power of respective connected loads to maintain virtual or phase zero as much as possible. This status persists until the relay swiches off.

Above principle is valid for standard application of WATTrouter controller shown in user manuals, where the current sensing module is placed directly on the line from main electricity meter to the house (this is recommended application). However, WATTrouter controller is versatile device and can be connected according to your needs. For example you can place the current sensing module just next to the PV inverter and then you can maintain the virtual or phase zero on that line.

Main features of all WATTrouter device series (both ECO and M)

  • Autonomous system, the only needed external device is an IBM compatible computer or notebook to configure the regulator
  • Easy to install and configure
  • Unmatched relationship price/added value
  • Three phase indirect current measurement
  • Three phase voltage detection to obtain power direction.
  • Fast calculation of active pover in either phase wire to obtain production surplus power.
  • Multiple control modes - sum of active powers ("virtual zero") or each phase wire independently ("phase zero").
  • 2 triac outputs up to 2,3 kW for heating devices - e.g. boilers, heat elements, infrared heaters, standalone dryers, floor heating elements, swimming pool heaters, etc. Can be used for bare heating elements placed in water as well.
  • 2 relay outputs for any consumers - suitable for motors, swimming pool pumps, air conditioners and another heating devices.
  • 2 SSR outputs for external solid state relays to switch more powerful heating devices
  • Swiching according to programmable priorites
  • Special quasi-proportional swiching mechanism on triac / SSR outputs to perfectly optimize the surplus usage. Swiching mechanism compliant to EN 61000-3-2 and EN 61000-3-3.
  • Very short dynamic response of the system (typical 2 seconds).
  • Built-in real time module for advanced timing techniques in both standard and CombiWATT modes.
  • Optional CombiWATT mode for combined load swiching in surplus control mode and low tariff mode. CombiWATT is necessary to switch the load when there is not enought surplus energy (winter, bad weather), in cases such as hot water preparation. This mode can work even if there is no low electricity tariff - it just takes the rest of the needed electricity from public grid.
  • 1 input for low tariff signal for CombiWATT mode.
  • Integrated time schedules for advanced real-time dependent system configuration.
  • Separated current sensing module and regulator for easier install to existing house wirings.
  • Possible to connect 2 current sensing modules in parallel to obtain 2 measurement points. (see user manual)
  • Software WATTconfig for Microsoft Windows XP and higher allows for comfortable configuration and monitoring over USB interface.
  • Firmware update for registered customers who purchased our product.
 

Advanced features of the WATTrouter M series

  • Enhanced connectivity due to integrated Ethernet interface.
  • Integrated web interface based on the AJAX/XML technology.
  • Fast UDP communication.
  • Software WATTconfig M for Microsoft Windows XP and higher allows for comfortable configuration and monitoring over both USB and Ethernet interfaces (this software can be run even under Linux in Wine emulator, but only UDP communication over LAN will be possible).
  • Straightforward online monitoring from Internet, you only have to setup NAT forwarding table in your router.
  • Open communication protocol based on XML data exchange, to enable integration of the device into intelligent house solutions.