Electric surges also pose threats to the critical components of a solar power system, including panels, inverters and battery storage. In this guide, we will walk you through how you can protect your system from surges by selecting the correct DC SPD (Surge Protection Device). From surge current ratings, to selecting the correct SPD for solar system, this article provides expert tips on how to make your PV system safer and prevent expensive repairs.
Protect your photovoltaic power system with right surge protection
What is DC SPD for Solar System?
DC SPD (constant current surge protection device) protects the system from electrical surges due to lightning or grid problems for solar systems. Basically, it diverts excess voltage to non-sensitive components such as panels or solar inverters. This ensures the system continues to operate and prevents costly damage.
The biggest benefit of using SPD for solar system is that it improves the system safety. Solar systems are also vulnerable to electrical disturbances which can cause downtime and expensive repair without a DC SPD. The proper SPD installation is for an optimal solar system performance.
Important Parameters to Select the Right DC SPD for Solar System
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Surge Current Rating
Different solar system components require different amounts of protection, and the surge current rating of a DC SPD should be carefully matched to the protection needs of those components.
- For solar inverters the SPD typically requires a surge current rating of 20 kA to 60 kA. The amount depends on the inverter size and how electrical surges effect the system.
- Solar panels are usually less sensitive but still vulnerable, and would usually require a SPD with a surge current rating of around 10 kA all the way up to 20 kA.
- Battery storage systems also require SPDs rated for at least 20 kA.
If your system comes with high surge current requirements then you need to use several SPD’s in parallel to provide additional protection. To prevent damage due to lightning strikes, grid transients or other electrical disturbances, selecting an SPD designed with the correct surge current rating is very important. A low current surge may not adequately protect a solar system against high current.
Surge Current Rating
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Voltage Protection Level (VPL):
The Voltage Protection Level (VPL) of a DC SPD should be low enough to protect solar panels and inverters from damaging voltage spikes. The VPL should also be sufficiently high to prevent tripping in a normal operating state.
For example, the residential solar systems usually have 600V voltage level while the commercial systems use 1000V to 1500V DC SPDs. Type 2 DC surge protection devices and Type 1+2 DC SPDs are the common type of protection for these systems since it provide protection against protection mode (DC +/-) – PE, (DC -) – PE or (DC +) – PE up to 2200 V or 7250 V.
A suitable VPL only diverts excessive voltage during surges while leaving your system safe and operational otherwise.
Voltage Protection Level (VPL)
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Response Time:
The delay time of DC SPDs used in the photovoltaic power system has considerable influence on the short time for protecting against transient voltage spikes. This shows that this response time should be less than 25 nanoseconds (ns). This also enables the SPD to react quicker to a surge that diverts excess voltage to the SPD before it reaches sensitive components like the inverter or solar panels.
If the SPD has a slower response time the spikes may get through damaging the system. It can also result in costly damage and system downtime due to delayed protection. Hence, selecting an SPD with a short response time is important in protecting your solar system.
Response Time
Type of SPD (Type 1, Type 2, Type 1+2)
When selecting a DC SPD for a solar panel or inverter, it’s important to examine the various types of SPDs available. They each serve for different purposes and then there’s protection at different levels of the system.
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Type 1 SPD
It is intended for use in protecting against the direct strike of lightning and very large surges. It usually goes onto the grid point where the system starts. The Type 1 SPDs operate to a maximum continuous operating voltage (Uc) of 150V to 440V. Type 1 is rated to 25kA of impulse discharge current (Iimp) that gives large protection to the system for large surges.
Protective elements such as Gas Discharge Tubes (GDT) and Metal Oxide Varistors (MOV) are fitted with Type 1 SPDs for handling of high energy spikes.
It’s used downstream often near the inverter to protect sensitive components from residual surges. Operating voltages are stated in these devices for between 600V – 1500V with a nominal discharge current (In) of 20kA and maximum discharge current (Imax) up to 40kA.
The Type 2 SPD utilizes the MOV technology for the protection of system electronics. It also makes sure the components are safe from lower energy surges which may still ruin the electronic components.
It is the best of both Type 1 and Type 2 SPDs with a full protection solution. This type is used at device level for local protection. It manages huge surges and residual voltage spikes along with nominal discharge current (In) of 20kA and impulse discharge current (Iimp) of 6.25kA. Type 1+2 SPDs are commonly used in systems where protection is needed at multiple points or where there is high surge risk.
Conclusion:
To protect against damaging surges, you must select the right DC SPD for your solar system. Proper surge protection enhances system safety, reduces downtime, protects your investment and prolongs the lifespan of your solar equipment.
LETOP is a trusted manufacturer for reliable DC surge protective devices for solar systems. We offers a full range of electrical control devices for PV systems that include DC SPDs for inverters, DC SPDs for solar panels (Type 1, type 2 and type 1+2), modular contactors and relays.
Protect your investment with LETOP. Contact us today for expert guidance and quality solutions!
FAQs
1. How many SPDs do you need for your solar system?
The number of SPDs required for a solar system depends on the size and configuration of that solar system. You normally require at least one Type 1 SPD at the point of entry for lightning protection, one Type 2 SPD near the inverter and more if applicable depending on other critical components such as battery storage.
2. Do solar inverters with built-in surge protection eliminate the need for a separate DC SPD?
Solar inverters with built-in surge protection offer some level of protection but may not be sufficient for all surge scenarios. A separate DC SPD provides additional protection against larger or residual surges that ensure more comprehensive safeguarding of the entire system.
3. What is the 10 meters rule for SPD?
According to the 10 meter rule for SPDs, they should be placed no more than 10m from an electrical panel or point of entry. It limits the chance of voltage spikes going to the sensitive equipment and ensures system safety.
