Content
Grid connected photovoltaic systems offer an ideal possibility for using solar energy in the household. They supply all electrical load without noise, pollution and hard wear for several decades.
The inverter NEG 1600 is the connection device between the PV-generator and the utility grid (250V/50 Hz grid). The Direct Current from the solar array is transformed into sinusoidal current, which supplies all connected AC devices. The excess energy is delivered to the public utility grid and will be used in the neighbourhood.
- for solar arrays up to 2000 Wp
- optimal usage of generator power by Maximum Power Point (MPP)-tracking
- very high efficiency even at low input power; optimal 94%
- very low stand-by consumption (3,1W)
- automatic switch-off at night
- low-noise, therefore installation in living area possible
- highest security due to Safety Extra-Low Voltage (SELV) and galvanic insulation
- long lifetime by use of conservatively rated high-grade components
- optional: measuring device with display or with connection plug for PC
- low entrance voltage, therefore higher energy profit when array is partially shaded .
Technical Aspects
The inverter NEG 1600 mainly consists of five functional elements: input
filter, switch-mode regulator, full-bridge, transformer, grid control unit.
They work together as follows: - The direct input current is filtered by
the input stage. - The switch-mode regulator, working as a step-down converter,
forms a pulsating DC out of the input DC. Passing the full-bridge, these
half-waves are turned into AC, which is fed to the grid by a trans-former.
The connection between device and grid is controlled by a grid-control
unit. In case of a grid-failure the device is disconnected from the grid.
- By MPP-tracking the inverter always gets a maximum yield of energy from
the PV-generator. Because the input energy is limited, arrays with power
up to 2kW peak can be installed. - The device reaction time on changing
power input is very short, so the device even works precisely at varying
radiation.
Safety
The NEG 1600 controls the line-to-line voltages of the three-phase system.
Therefore all directions for parallel running operation of in-plant generation
devices to the utility company’s low voltage grid are fulfilled. - The
control of grid-frequency and grid-impe-dance improves the switch-off behaviour,
so that no island-effect will happen. - In case the temperature of power
electronic components gets too high, the NEG 1600 will be disconnected
from the grid. - The inverter controls the PV-generator and prevents operation,
if the generator voltage is too high or too low. - The energy is fed into
the grid by a low-loss toroidal transformer with protective winding corresponding
to VDE 0551. This guarantees a galvanic insulation between AC and DC part.
- Because the input-voltage is limited to 110V, the requirements for Safety
Extra-Low Voltage (SELV) according to VDE 0100, part 410, are fulfilled.
Therefore it is not necessary to have additional means for security of
persons on the arrays or the DC-part.
Input-Voltage
The installation of the system is made easy because the input voltage is
in the area of safety extra-low voltage. Therefore the installation-staff
can get in touch without being endangered. By deviding the solar array
into several parallel strings, the losses caused by shade (because of trees,
houses) on parts of the array are low. - Because of fully developed electronic
circuit design the efficiency of the NEG reaches 94% even in operation
at partial load.
EMC - Electromagnetical Compatibility - CE-Certificate of Conformity
The NEG fulfils the new standards, valid since 1.1.96, for CE-marking,
corresponding to the EMC-directions. The NEG follows the limiting value
curves EN 55022, class B, referring interference radiation and the requirements
of EN 50081-2 referring immunity from disturbance (refer to technical data).
Quality
All power components work far below their limits. This guarantees a high
reliability of operation. In an extensive test procedure the functioning
of all sub-assemblies and of the complete device has been thouroughly checked.
Therefore the NEG has a long lifetime and the failure rate is very low.
- Each device has passed a five-hour test under full-load before delivery.
Ecology and Recycling
The modular construction of the NEG guarantees an easy exchange of single
components (which maybe damaged during performance), so that only small
parts must be wasted. Wherever possible, single components are linked by
screw connections (e.g.: capacitor of input-filter), so that demounting
is easier. This measure supports recycling, even at a higher cost for components
and mounting. At the moment a design concept is being worked at which allows
us to take back our devices and reutilize subcomponents.
Data Acquisition and Remote Indicator
As an option the NEG can be supplied with the data acquisition system
PGDAT. To connect the PGDAT with the inverter, each NEG is designed with
a special plug. The PGDAT offers two different data outputs.
Remote Indicator NEGDAT
Input-/ output-current or power which is fed to the grid can be indicated
on a LCD-dis-play by choice. The PGDAT also counts continuously the produced
electrical work. This is shown on a second display (in kWh or Wh). Even
when the inverter is switched off or in case of a grid-failure the PGDAT
keeps the count value of the solar power produc-tion. - A LED gives information
about the state of operation. - The NEGDAT is con-nected with the inverter
by a 25m long cable and therefore can be comfortably installed far away
from the NEG in the living area.
Data Acquisition
The data acquisition NEGDRS delivers the same data as NEGDAT, but on a
serial plug RS232. The NEGDRS can be expanded to a weather station or to
measure the data of the whole system. Therefore the device offers nine
additional inputs.
Software WRDAT
With the program WRDAT an IBM-compatible PC can read in, display and save
the measured values. This program will be delivered together with the NEGDRS
and also with standard software, written in GWBASIC and Turbo Pascal,
which allows to read out the data, print and process further.
Input
DC (output solar array)
- Maximum voltage 110V ( -10°C)
- Power of PV-generator max. 2000W
- Voltage level 54V - 95V
- Max. input current 29A
- Input power 20W -1600W
- Transient protection 110V; integrated in the device
Basic Specification:
Living, trade and industrial area
AC-part:
Interference suppression standard CENELEC; EN 55022
VDE 0871 part 11, class B
Output AC to grid
output voltage: 230V (+10% / -15%) sinusoidal
output current: 6,6A sinusoidal
Total harmonic distortion: <3,5%
Power factor (cos phi): 20% Prated: cos phi =0,95 / 40% Prated:
cos phi =0,99
DC-part:
Interference suppression standard EN 55022 VDE 0871, part 11,
class B Immunity to interference EN 55081-2 IEC 801-4, level 3 (1000V)
Overvoltage disconnection at 256V (AC output)
Undervoltage disconnection at 195V (all-pole following VDEW)
Voltage control
one-phase following IEC, EN and three-phase following VDEW
Frequency control deviation ±1%
Disconnecting from grid
galvanic, following VDE 0551, toroidal-core
security-transformer with protection winding
Switch-off unit
relay JR1AF16A following VDE 0660
certifications SEV, TÜV, UL, CSA
Case insulation class IP 20
Dimensions of the device 420*335*160 mm
General
- Input to network if more then 20W
- Operating frequency 24kHz
- Ambient temperature
- permissible 0°C to 50°C
- recommended 4°C to 40°C
- Weight 25kg
- Feedback control MPP-tracking or fixed-voltage control
Warranty
3 years