DC Power Protection

DC Power Protection

Choose from the range of DC Power Protection by clicking the images below

Eritech TDS50

Eritech TDS50 Surge Diverters are designed to provide economical and reliable protection from voltage transients on solar PV (photo voltaic) systems. Their compact design fits into inverters and solar combiner boxes, and they are conveniently packaged for easy installation on a DIN rail. Separate plug and base design and hot swappable feature allows ease of module replacement.

Click here for a PDF brochure of the TDS50 Surge Diverter.

DSD140-2BR 24/48

The DIN Surge Diverter DSD140-2BR 24/48 product has been designed to provide surge protection for both 24V and 48V DC power systems, such as the floating DC supplies typically used in solar cell applications. Three modes of protection (line to line, and both lines to ground) are provided to give comprehensive surge protection to these usually floating systems.

The unit has a maximum continuous voltages Uc of 60Vdc (48Vac) from line to line, and has a 275V from each line to ground.

Status Indication

DSD modules incorporate an internal thermal disconnect element, which automatically disconnects the varistor from the network in the event of a thermal overload. A failure of the module itself, or a sustained abnormal over-voltage on the connected supply could cause this situation. Should the internal disconnect operate, a red flag appears in the transparent window of the Status Indicator(s) on the front of the DSD.

Remote Status

The DSD provides for remote status monitoring via voltage-free relay contacts. Failure of the DSD is signified by the N/C contacts (11,14) opening and the N/O contacts (11,12) closing. Ensure that the voltage and current ratings of the contacts are not exceeded (see table at right).

DSD140-2BR 24/48

With the growing awareness of global warming and the need for effective energy conservation, we are increasingly looking to new sources of renewable and eco-friendly energy. One of the front-runners in this search for ‘safe’ power is the use of photovoltaic (PV) and/or solar thermal sources – in other words, Solar Power. Such systems by design are located outdoors, and as such are susceptible to the damaging effects of lightning strike. Surge currents and surge voltages constitute a severe threat for PV systems.
To ensure safe and reliable operation, these systems must be protected with suitable earthing and surge protection measures.

Earthing

Although it is not essential for the satisfactory operation of your system, the manufacturers of solar panels recommend that solar panels be earthed. Earthing with respect to photovoltaic installations serves several purposes:

1. it bleeds off static electric charge built up from wind and rain;
2. it is an integral part of lightning protection;
3. it provides fault protection, whereby any shorts or faults in circuitry will conduct enough current to ground to trip circuit breakers or fuses
and allow fault detection. It is recommended that the earth stake should have a resistance to ground of 25ohm or less. For adequate
lightning protection, between 1ohm and 5ohm resistance to ground gives fairly reliable lightning protection.

 Surge Protection

Photovoltaic installations are frequently in isolated and elevated locations, combining with their large surface area to make them prime targets for lightning strike and the resulting overvoltages. Therefore, it is necessary to guard against lightning and surge damage to the system itself and any connected structures.

Eritech TDS50 Surge Diverters are designed to provide economical and reliable protection from voltage transients on solar PV (photo voltaic) systems. Their compact design fits into inverters and solar combiner boxes, and they are conveniently packaged for easy installation on a DIN rail. Separate plug and base design and hot swappable feature allows ease of module replacement.

Click here for a PDF brochure of the TDS50 Surge Diverter.

Photovoltaic (PV) Bonding

For many PV modules, special earthing arrangements are required. As an example, Thin-Film modules may suffer from TCO (transparent conductive oxide) corrosion, which can destroy the entire PV plant. PV modules with backside contact cells may see a reduction in efficiency of approx. 30% due to polarisation effects. To prevent these issues, manufacturers specify the earthing of the negative/positive side of the DC string.

TCO corrosion is an inherent problem for all thin film technologies, but can be effectively blocked by the implementation of adequate inverter earthing and tightening of the module edges. Both measures are recommended.

Note: It is especially important that PV frame earthing is provided when using non-isolated (transformer-less) inverters.

Types of earthing in a PV Array
• Protective earthing: earthing of exposed parts
• Functional earthing: system earthing (+ve or -ve of PV array)

System Earthing
– why do it?
• Performance (i.e. PV modules)
• Warranty (i.e. TCO layer corrosion in some thin film modules types)
• System design choice (i.e. earthed battery bank on stand-alone power system)

Earthing +ve conductor
Modules that utilise back contact conductors may require +ve conductor
bonded to earth to achieve maximum performance

Source:SunPower Corp.

Thin film module degradation
Damp-heat-test with negative Bias Voltage (NREL)

Above: “Bar Graph Corrosion” of an a-Si-module after 200 hours at 85°C, 85% RH and a negative bias voltage (-600V) from cells to frame.
Source: Osterwald et al NREL2003

TCO on superstrate construction
Source: Dr. Herbert Schmidt, Franhofer Institute

Summary of TCO Corrosion

  • Still incomplete understanding of TCO corrosion
  • Migration of Na+ ions from glass probable cause
  • Superstrate technology (a-Si & CdTe) has higher risk
  • Substrate technology (CIS, partially a-Si) less affected
  • Accelerated damage through humidity and high temperature
  • Construction and material of edge seals are of key relevance
  • A metal frame increases rate of degradation
  • Negative voltage potential to ground has a strong acceleration effect (earthing of solar negative recommended)

Protective Earthing

  • Earthing of PV array frame to protect against electric shock hazard from indirect contact through capacitive coupling with the PV array by touching modules or the module/array frame
  • Not just a theory – incident has already occurred in Australia
  • Now a requirement iin the CEC GC Installation Guidelines for all LV PV arrays
CAPACITIVE COUPLING:

Photovoltaic (PV) Bonding

ERITECH® brand solar bonding lugs are designed to bond the frames and mounting structures of solar photovoltaic systems in accordance with NEC® requirements. These lugs are corrosion-resistant and galvanically compatible with copper grounding conductors and aluminum photovoltaic module frames.

The solar bonding lugs are supplied with the required mounting hardware and are easy to install. The stamped lug has a lay-in feature that allows the positioning of the grounding conductor along multiple frames prior to securing the wire. In addition, the same hex head power driver can be used to install the lug to the frame and secure the wire into the lug.

Part Number Conductor Range Material
EL6CS 14 Sol – 6 Str
1.5 -16 mm2
Copper Alloy
Instructions N/A Instruction sheet for Solar Bonding Lug

Features:

  • Common hardware used for attaching the lug and securing the conductor to simplify installation
  • Provided with all hardware shown
  • Stainless steel hardware includes serrated washers for superior bond to anodized aluminum
  • Lay-in feature is ideal for installation underneath module frames
  • Accommodates 14 Sol – 6 Str AWG (1.5 -16 mm2) copper grounding conductors
  • UL® 467 Listed