Control Techniques SPV systems are a range of transformerless central inverters for PV installations from 145kWp to 1.76MWp. Each inverter is constructed using multiple standard 145kWp or 175kW modules.

Intelligent Inverter Management (IIM)

The modules are controlled by Control Techniques unique Intelligent Inverter Management (IIM) system to maximise energy yield by controlling the active and standby status of each inverter module. The active and standby sequence for each module is rotated so that duty is shared and inverter life extended. IIM has other benefits of energy efficiency and increased reliability:

Enhanced efficiency

• Modularity allows the active inverter capacity to be continuously scaled to optimise energy efficiency for all conditions
• The system generates energy in lower light conditions

Enhanced availability

• In the event of any inverter module trip, the system automatically reconfigures to continue generating.
• For critical applications built-in redundancy can be incorporated within the system to maintain maximum output with a small additional investment.

The following graph demonstrates the high efficiency of the system, which remains above 96% at only 3% of full load. This compares to conventional bulk inverters where the efficiency begins to reduce severely below 20% of full load. Yield at low load is particularly important in temperate climates such as northern Europe.

High accuracy MPPT algorithm

To ensure maximum power is obtained from PV arrays, Control Techniques' unique Maximum Power Point Tracking (MPPT) algorithm is optimised for accuracy for both crystalline and thin film solar panels. The system is able to adapt rapidly to fast moving weather conditions across a wide temperature range.

Key inverter features

• High conversion efficiency, 98.0% peak, 97.6% EU factor
• Optimised for reliability and long active life
• Standard industrial mass produced inverter modules
• Power increments of 175kWp from 145kWp to 1.76MWp
• Compact inverter footprint
• Low switch-on point of 900W (0.05% on 1.76MW inverter)
• High accuracy Maximum Power Point Tracking (MPPT) over a wide voltage range
• Engineered for compliance with international grid connection codes
• Automatic reactive current and power factor control
• Anti-islanding and supply dip ride-through
• 3.3% total harmonic current distortion (ITHD) - no transformer de-rating required
• Tolerant to inverter module faults with fast automatic recovery
• Communications and PC tools for local or remote configuration and monitoring

Options

• Built in inverter redundancy
• Communications via Ethernet (Ethernet/ IP, Modbus TCP/IP, TCP/IP web server), Modbus RTU, Profibus DP, Devicenet
• DC fusing or circuit breakers AC / DC side switches +/- DC side grounding
• Single piece or split AC side / DC side construction
• DC overvoltage protection (use is compulsory)
• Inverter powered shelter cooling fans
• OPC Server
• Utility interface
• Up to 1000V switch-on