How to handle emergency cases in PV system(Part III)

Author: Jonas

2022-07-11 11:16

How GoodWe solutions cope with extreme weather

PV systems are always exposure to natural elements (sunlight) so it’s fair to say that weather is the primary consideration in the design, creation, and installation of all components. All PV system components endure rigorous tests to ensure they are durable enough to withstand a reasonable level of severe weather. But some extreme weather scenarios could limit their production or efficiency.

Since there are a variety of situations surrounding extreme weather, let’s go through the most common scenarios to see how GoodWe solution fares.

Extreme hot and cold temperatures

We tend to associate warm climates with sunlight, but the sun still rises each day in cold climates, and that exposure to sunlight, not air temperature, is what most influences solar production. Many of the places where solar is most common in the United States (like Massachusetts, New York, or New Jersey) have plenty of cold days throughout the year.

It’s not to say that temperature doesn’t influence the PV system at all because there are extreme points at which panels or inverters become less efficient.

If the environmental temperature becomes very high then inverters are likely to start losing efficiency, while cold temperatures shouldn’t negatively impact the power generation. GoodWe inverters have a very wide operating temperature between -30℃ and 60℃, which could cover most regions of the world.

Thanks to the good internal space and heat dissipation design, GoodWe inverter can dissipate heat well at high temperatures and maintain a high-power generation. For residential series like MS and SDT G2, the inverters can operate till 40℃ without power derating, while for the C&I series this value could be increased to 45℃.

Wind and Hail

Roofs are very susceptible to wind damage. Selecting a roofing material capable of withstanding high wind is critical to ensuring the safety of your home. Wind direction and speed can vary frequently and rapidly which presents a challenge to the wind performance of roofing materials. High wind applies negative pressure on roofing materials that tend to lift roof surfaces from roof structures. GoodWe SunshineTile combined with structurally designed stainless steel brackets has passed a wind test of wind speed of 177km/hour, or a gale of 15 wind. Debris carried by the high wind can also pose a risk of damaging roofing materials. Similar issues can be a result of hail in some parts of the world. SunshineTile, with tempered glass as the front surface, has passed the hail test of withstanding hail of 25mm in diameter at the speed of 23m/s.

How to protect the system when no one on-site?

The Covid-19 pandemic has greatly affected the people traveling, including the maintenance staff in PV industry. In some unexpected situations, we need to turn off the inverter to protect the PV system, but what to do if there is no one on-site?

Fig.9: Covid-19 affects the O&M

Remote Shutdown

The remote shutdown function that comes with the inverter can be realized by a shutdown function circuit integrated into the inverter and a switch. It requires the combined action of an on-off switch, long-distance communication, and a control mechanism via signals.

The on-off switch can be deployed in a remote place, where the operator can turn on or off the switch at a safe distance to control the inverter. Communication cables such as RS485 are used to connect the inverter and switch to transmit signals of a remote shutdown. To realize communication between multi-inverters and one switch, inverters should be connected hand in hand as shown in figure 5. When the operator turns on the switch, signals of remote shutdown shall be sent to multiple inverters at the same time, and the inverters should disconnect from the grid and stop power output within 0.5s.

Online Shutdown

Similar to the principle of the remote shutdown, the GoodWe monitoring platform SEMS Portal integrates the function of shutdown. With one click on the website, the GoodWe cloud server will send a signal to the inverter through the communication tools and then shut down the inverter on the AC side in minutes.

Conclusion

When dealing with electricity, safety has the top priority. Every electrician must be very careful when it comes to safety and must take the necessary protective measures. This post identifies the main emergency cases in a PV system including fire and lightening, also how to deal with the emergency cases is also included. In critical applications, AFCI should be equipped for a reduced risk of DC arc fault. RCMU and RCD can against the fire risk caused by the residual current. RCD can also be a life-saving device that can prevent humans from getting a fatal electrical shock. To minimize the risk of human contacting with the live cables, the emergency switches of remote shutdown is used to separate the power from the AC grid. Also, we provide device protection like SPD against damage from surges.

With all protection functions integrated into a small body, GoodWe solutions escort your PV system.

Please read Part I of this article, as well as Part II.