Things to consider while choosing the Solar Installer for Your Residential Solar Project

1. Experience and expertise: Choose a solar installer who has experience and expertise in the field. Look for installers who have been in business for several years and have a track record of successful installations.

2. Licensing and certifications: Check if the installer is licensed and certified to install solar panels in your area. A licensed and certified installer will have the knowledge and skills to ensure a safe and efficient installation.

3. Reviews and references: Look for reviews and references from previous customers. This will give you an idea of the installer's reputation and the quality of their work.

4. Warranty and maintenance: Ask about the warranty and maintenance offered by the installer. A reputable installer will provide a warranty on their work and offer maintenance services to ensure the long-term performance of your solar panels.

5. Financing options: Check if the installer offers financing options. This can help you save money on the upfront costs of installing solar panels.

6. Quality of equipment: Ask about the quality of the solar panels and other equipment that will be installed. Look for high-quality equipment from reputable manufacturers that come with a warranty.

7. Customer service: Choose an installer who provides excellent customer service. They should be responsive to your questions and concerns, and provide ongoing support after the installation is complete.

8. Cost: Compare the cost of installation from different installers. Look for an installer who offers a competitive price without compromising on the quality of their work or equipment.

What is PID in solar modules ? Can it be avoided ?

PID stands for potential induced degradation. It is an important issue of performance degradation in crystalline silicon solar panels. The degradation could be high as 30% or even up to 70% in some cases. The degradation occurs in solar energy systems and can be reversible or irreversible.

Potential-Induced Degradation (PID) is a common phenomenon causing PV panels to lose power generation by up to 80%. Power reduction may occur over time or can happen within days or weeks after installation.

The PID process in the PV module may grow very rapidly and in the shortest period will affect the performance of an entire PV system. Consequently, this results in damaging effects on PV system project financing, operations and economics at all installation levels: residential, commercial and utility-base. It is essential to understand and address the PID problem in its early stages, to ensure PV module performance over the entire system life – PID can be prevented and recovered on system level altogether.

Causes of Potential Induced Degradation (PID)

PID occurs because of minor, unwanted currents between the semiconductor on the one side, and the glass, anti-reflective coating (ARC), the frame, and the mounting on the other side.

The degradation in performance is associated with migration of sodium ions, from the glass plate through the encapsulation (commonly: EVA) and the Anti-Reflective Coating (ARC) to the cell.

This would be caused when due to a particular manner of string earthing, the semiconductor in a cell acquires a negative potential with respect to the encapsulation and the support structure.

The presence of these ions causes an effective shunt path across the cell and reduces the output. The effect is somewhat cumulative with time and has a greater extent when the cell is operated at a higher negative potential with respect these parts.

PID promote factors

Temperature and humidity are both known to promote PID. However, there is not much one can do about these factors once a system is installed in a given location.

Dependence on Location in String

Recall the words “higher negative potential” in the explanation above. If the positive terminal of the string is taken as system ground and the mounting structure connected to the earth potential, the cell closest to the positive terminal has the least negative potential with respect to earth, and hence the least PID effect.

The cell closest to the negative terminal will experience a high negative potential relative to the grounded structure and will undergo maximum PID. Thus cells, modules and panels will experience PID according to their position in the string.

Avoiding / Mitigating PID

The following considerations are applicable:

• Location– for a new plant, within other limitations, a site with lower temperature and humidity should be selected. Note that a windy site will also keep the system cooler.

• Use PID Resistant Hardware– for a new set up, there are modules available which are resistant to PID. However, the cost will be higher due to use of more expensive encapsulating materials, anti-reflective coatings, and other materials. A compromise may have to be made for overall profitability by using panels subject to PID and adopting other mitigating techniques.

• Earthing- Use modules where there is no restriction imposed by the manufacturer on connecting the negative end of the string to system ground.

• Charge Equalizers– are built into inverters. When the inverter is inactive at night, they apply an opposite bias to the panel which cancels out the reversible type of PID effect overnight. Reversible PID is also called polarization.

Any other way to reduce PID Impact :-

Sungrow and TÜV Rheinland have jointly issued PID Zero – an anti-PID solution whitepaper for residential PV systems. Equipped with patented mirror boost topology and an intelligent control algorithm, the innovative PID Zero solution provides 24-hour anti-PID protection, enabling more effective PID suppression during the day and PID recovery at night, significantly reducing power generation losses due to module performance degradation.

What is Arc Fault in Solar Systems and how to deal with it ?

An arc fault in a solar system occurs when an electrical current jumps across a gap between two conductive surfaces, creating a brief but intense burst of heat and light. This can happen when there is damage or wear to electrical wiring, connectors, or other components in a solar PV system, creating a pathway for the current to arc.

Arc faults can be dangerous because they can start fires, damage equipment, and cause system failures. In addition, they can be difficult to detect because they often occur in areas that are not visible or accessible.

To address this issue, many modern solar systems include arc fault detection devices (AFDDs) that monitor the system for signs of arcing and can automatically shut down the system if a fault is detected. These devices help to improve the safety and reliability of solar PV systems. Along with AFDDs there has to be An AFCI or Arc Fault Circuit Interrupter. An AFCI or Arc Fault Circuit Interrupter is a device used to detect arcing in an electrical circuit and to interrupt the flow of current. It is installed in many types of electrical circuits to reduce the chances of an electrical fire due to faulty wiring, bad wiring connections or damage sustained during wiring installation.

Possible Arc Fault Causes:

1. Connections in junction boxes can degrade (oxidize) over time creating hot spots.

2. Screw type terminal connections can come loose due to changes in temperature.

3. Improper stripping length can result in wire insulation being captured in terminals.

4. Improper crimping of DC terminals results loose connections and arcing.

5. Improper connector assembly results in connection not being "locked" and arcing.

6. DC connectors not fully mated causes arcing.

7. Animals chewing through wires or wiring that has come loose and rubbed against the array racking can also lead to serial arcing.

8. PV Panels are cracked or damaged.

9. Firmware is out of date

10. AFCI Board is damaged or connection to DSP is damaged

Detection of Arc Fault Causes:

Most of these are common conditions and easily identified with a quick visual inspection. First of all, arcing leaves some evidence. The may be discoloration of wiring and racking, melted connectors and insulation or even burned junction boxes on the back of panels. A quick visual inspection can locate such issues very reliably. A gentle tug on DC cables whether in the home run connections, panel to panel connections or in the combiner/wiring box can locate wires that have loosed or were not terminated properly. The below picture is an example of improperly terminated DC connections in a wire box and blindly resetting an Arc Fault without verifying all DC connections. The DC circuit includes all connections, even those in the inverter.

Another method to locate arc fault issues is somewhat easier to execute, but does not pinpoint the issue to a specific connection and the results can be difficult to interpret.. For rooftop installations, it may not be easy or even possible to perform the above visual and manual inspection. In these cases, it is recommended to use some sort of high voltage tester to test the cabling to locate a failure. A “Megger” or megohm meter is one example of a simple test set that can help locate arcs to a specific string. For more testing functionality, a string tester is preferred because it can detect not only serial arcs, but also insulation issues and ground faults in the DC cabling. While it is considerably more expensive, it is far more flexible than the simple “megger” and can be useful in troubleshooting other array issues.

Both of these devices usually test at 250V, 500V and 1000V. Neither test at 600V which is what residential and some small commercial systems are rated at for maximum VOC. If the PV and DC wiring is only rated at 600V, use the 500V setting to test. If the system uses panels and cable rated at 1000V, even if it is residential, it is suggested to test at 1000V. The reasoning is simple; a fault may only occur at voltages higher than 500V on cold bright days in a 600V system. The test may pass at 500V, but can fail at 1000V. When using the megger, a failure indication is a resistance that is higher than "nominal zero". A 'nominal zero' will not be zero ohms, but the baseline resistance that was recorded during the system commissioning tests. Once the faulty string is isolated, then the first method can be used to locate the faulty component.

A final method that can be used is to measure the temperature of the connectors, terminals and junction boxes using an infrared thermometer. These thermometers are quite cheap and effective; they can be purchased from any big box home improvement store. Typically, a connection that has a significantly higher temperature than like connections has a higher resistance and may be causing arc faults. When measuring the temperature of the connections, take into account the location of the connection; a connection that is in direct sunlight may read a higher temperature than one underneath PV panels.

If after all these tests no defect is found, then it is safe to assume that a “false” or nuisance trip has occurred. In this case, reset the fault and observe the inverter to see if it immediately faults again. If so, The AFCI circuit may be faulty and the inverter needs replacement. If not, try to record the exact conditions when the arc fault occurs. It may not be a sensitivity issue, but a weather related issue. Check local weather to see if there were any special conditions that may have contributed to the suspected “false” trip.

A simple rain storm can also uncover issues on a system including arc faults that only occurs when the wiring is wet. Finally, report any findings back to the inverter manufacturer. You input is very valuable in the continued refinement of equipment. A manufacturer tests to many conditions to cause a failure, but nothing can completely replicate the conditions on your sites in the real world.

How to deal with Arc Faults:-

Here are some steps you can take to deal with an arc fault in a solar system:

1. Shut off the system: The first step to dealing with an arc fault is to shut off the solar system to prevent any further damage or risk of injury. Turn off the circuit breaker or disconnect switch that supplies power to the system.

2. Locate the fault: Use a thermal imaging camera or other diagnostic tools to locate the fault. The thermal imaging camera can detect hot spots where an arc fault is occurring.

3. Inspect the wiring: Once you have located the fault, visually inspect the wiring and components for any damage or signs of overheating. Look for loose connections, frayed wires, or any other visible signs of damage.

4. Repair or replace damaged components: If you find any damaged components, repair or replace them as necessary. This may involve replacing a damaged wire, tightening a loose connection, or replacing a damaged component such as a fuse or circuit breaker.

5. Test the system: After making any necessary repairs or replacements, test the system to ensure that the arc fault has been eliminated. Turn the system back on and monitor it for any signs of overheating or other issues.

6. Seek professional help: If you are not comfortable working with electrical systems or if you are unable to locate or repair the arc fault, seek professional help from a licensed electrician or solar installer. They can help you diagnose and repair the problem safely and effectively.

In general, it's important to regularly inspect and maintain your solar system to prevent arc faults and other potential hazards. Regular maintenance can help ensure the safe and reliable operation of your solar system for years to come.