Top 10 Mistakes to Avoid When Building Your First Solar Power System
Building a solar power system can be a great way to save money and reduce your carbon footprint. However, for beginners, certain mistakes can be costly and even dangerous. In this article, we'll explore the top 10 most common mistakes that beginners make when building their first solar power system, and how to avoid them.
Table of Content
- No. 10 Connecting a Solar String to a Device without Checking the Voltage
- No. 9 Not Enough Batteries or Solar Panels
- No. 8 Building a System that Cannot be Scaled
- NO. 7 Using Low-Quality Circuit Breakers and Improper Fuses
- NO. 6 Using Copper-Clad Aluminum Cables
- NO. 5 Soldering Large Lugs
- No. 4 Messy Wiring Jobs
- No. 3 Improper Wire Gauge
- No.2 Incorrect or Low Quality Tools
- No.1 Loose Terminals
- Bonus：A Schematic Diagram of RV Solar System
No. 10 Connecting a Solar String to a Device without Checking the Voltage
It's crucial to ensure that the voltage is within the working range of a device, as too high or too low voltage can result in permanent damage or failure of the device.
Unfortunately, many people overlook this and end up destroying their solar charge controllers by connecting too many solar panels in series, causing the voltage to exceed the recommended limit. Alternatively, using low-voltage panels in parallel may not produce sufficient voltage for the solar charge controller to function properly. Therefore, it's essential to check the voltage and make sure it falls within the working voltage range of the device before connecting it. Remember, every device has its own working voltage range, and avoiding these issues will save you from costly damage and loss of functionality.
Let's say we have a solar charge controller, and you'll notice a sticker on its side that lists the minimum and maximum solar voltage required for it to operate. However, please note that the voltage measurements are based on open circuit voltage (VOC), which is when the solar panels aren't connected to the device. Therefore, before connecting the solar string to the device, it's essential to use a voltmeter to test the voltage and ensure that it falls within the working voltage range specified on the sticker. This precautionary step will prevent any damage or malfunctioning of the device and ensure that your solar panel system runs smoothly.
No. 9 Not Enough Batteries or Solar Panels
It's common for people to discharge their battery to zero and assume it's broken when they see zero volts. However, the real issue may be that they don't have enough solar panels or batteries to sustain their system's needs.
Furthermore, your battery should never be discharged to zero percent, as this can damage the battery. To prevent this, you should use devices like inverters with low voltage disconnect features. This is a handy feature found on many inverters that turns off the loads and stops the inverter's output once the battery bank reaches a certain voltage. With my current system, for example, everything turns off automatically at around five percent. Without a low voltage disconnect, your batteries will go into safety mode, and you may need to use an alternator or battery charger to wake them back up again. Regardless of the presence of a low voltage disconnect, you should always have enough battery power to ensure backup for a few days.
No. 8 Building a System that Cannot be Scaled
When building a solar power system, it's essential to consider scalability and future expansion. This is because you're likely to want to add more batteries and solar panels in the future, given that you're using the system every day. To ensure your system is scalable, there are several measures you can take, such as having large bus bars that can handle high currents, allowing you to add more batteries whenever necessary. Additionally, use larger cables than required, mainly if you plan to upgrade your inverter shortly. Copper cables can be expensive, and buying new ones each time you add a device can be costly. Besides, purchasing a solar charge controller that's larger than required or has multiple inputs enables you to add more solar panels in the future. During winter when you need more power, you could even add another string of panels with such controllers. By future-proofing your solar power system, you can make it more scalable, saving you time and resources in the long run.
NO. 7 Using Low-Quality Circuit Breakers and Improper Fuses
One of the most common mistakes made when designing solar power systems is using low-quality circuit breakers or selecting the wrong circuit breaker or fuse for the job.
For instance, a high-quality circuit breaker that's rated for 42 volts DC maximum cannot be used with a 48-volt system. Similarly, circuit breakers are rated for either DC or AC applications, so a breaker rated for AC applications cannot be used to disconnect the battery or any other DC device. It's essential to choose DC-rated devices, such as a marine-grade circuit breaker that can interrupt a DC arc, which is harder to extinguish than an AC arc. However, always note that DC-rated devices have voltage limits, so check the data sheet and ensure it's appropriate for your needs, especially when dealing with lithium iron phosphate batteries. Home circuit breakers are typically AC-rated only and are not suitable for large batteries' disconnection. Fuse boxes should also be of high quality, especially for low-voltage DC systems like 12-volt systems. Avoid low-quality fuse boxes on Amazon to ensure optimal safety and reliability of your solar power system.
NO. 6 Using Copper-lad Aluminum Cables
One common mistake made by beginners is using copper-clad aluminum cables that come with cheap inverters on Amazon. These cables are unsafe and can pose a fire hazard, so it's best to avoid them at all costs. Instead, use only pure copper cables. Although copper-clad aluminum wire looks like copper on the outside, it's actually made of aluminum inside, which expands and contracts differently than copper, causing loose terminals and poor conductivity over time.
Furthermore, the wires that come with cheap inverters are typically undersized, leading to problems down the line. If you encounter such cables, it's best to discard them immediately and make your own cables out of pure copper. Remember, safety should always be a top priority when working with solar power systems, and using high-quality materials is crucial for ensuring optimal performance and avoiding potential hazards.
NO. 5 Soldering Large Lugs
One mistake that some people make when working with large copper cables and lugs is soldering them together.
However, this is incorrect, and using the proper crimping tool is a much better option. Crimping creates a gas-tight mechanical connection that's superior to a solder joint for several reasons. A cold-welded mechanical connection allows metals to become one, sharing electrons and providing the lowest resistance path for electrons to flow.
On the other hand, soldering involves dissimilar metals flowing into a space, creating lots of surface area for conductivity to occur, which results in higher resistance than a crimped connection.
Additionally, mechanical connections are more resistant to corrosion, contrary to popular belief that soldering is better, especially in marine environments. You can achieve better results by using a dry copper lug and cable, terminating it correctly, and covering it with marine-grade heat shrink.
Every manual for low voltage DC electronics, particularly for marine applications, recommends crimping over soldering, making it the correct choice for large gauge cables. Soldering requires hot temperatures to effectively flow, and this may damage the wire insulation or not get hot enough, leading to an unreliable connection.
By contrast, crimping is stronger, and you can check the connection by cutting it open and observing how all the metals are cold welded together. Although some people may enjoy soldering, it's illogical to do so on cables, and using proper crimping tools is essential for reliable solar power systems.
No. 4 Messy Wiring Jobs
Messy wiring jobs can be a significant problem when building solar power systems, and it's crucial to organize the wiring correctly. Exposed battery terminals covered in a nest of wires are not safe, while having more than three lugs to a single terminal is also not ideal.
When organizing wiring, it's essential to space out everything, allowing you to see every conductor and label them if possible. Bundling too many wires together, particularly with zip ties, can cause heat buildup since high current conductors wrapped together cannot dissipate heat as designed. Conversely, freestanding cables can dissipate heat, keeping them at low temperatures. If there are lots of wires bundled together, heat will not escape, creating hot spots that can cause fires and melted insulation. Therefore, let the wires breathe, label them, color-code them nicely, and ensure they look good. Proper organization of wiring jobs ensures safety, eliminates hotspots, improves performance, and makes maintenance easier.
No. 3 Improper Wire Gauge
Improper wire gauge sizing can be a significant issue when building a solar power system, especially for beginners. It's essential to find a chart that shows the maximum ampacity of copper you're using to ensure it can carry the current from the battery, solar panel, or any connection in your system. The chart will show how much current a conductor can carry without overheating and causing damage or starting a fire. If a cable is undersized, it'll throw off voltage readings, affecting devices' proper function, especially those with voltage sensing capabilities.
picture source: thespruce.com
The best way to avoid problems is by oversizing your conductors or following the manual recommendations for your devices. With solar charge controllers, for instance, use the largest size copper that safely fits in the terminal and keep the cables short. Every device has a manual with recommended cable sizes, so it's vital to read the manual. When connecting batteries to the solar charge controller, look up the max size cable you can fit into the terminal safely and use that.
It's preferred to oversize wiring for an inverter, especially if running inductive loads like large motors. Choose the largest cable possible to have a cool running cable and proper voltage sensing capabilities for low voltage disconnect. However, be careful not to over-gauge wires to the point of causing problems with the device's connection. For example, putting a 4 AWG cable on a small circuit breaker is a bad idea since there may not be enough space for that much copper on the terminal. Therefore, always think through and try to oversize wires wherever possible, but not to cause more problems. Proper wire gauge sizing ensures optimal performance, safety, and reliability of solar power systems.
No.2 Incorrect or Low Quality Tools
Using incorrect or low-quality tools can be a significant issue when building solar power systems. Cable cutters should not be used to strip cables, and instead, cable strippers should be used. High-quality cable strippers from Germany or England last for years and are essential tools that everyone building systems should have on hand. Similarly, it's important to use high-quality crimpers, since cheaper ones may cause problems.
When working with live batteries, insulated tools like insulated ratchets and high voltage-rated screwdrivers are crucial for safety reasons. Don't try to use pliers for crimping connections, but instead, always use crimpers. Electrical-specific pliers have features made for electricians that are useful if you know how to use them.
Buying good tools is critical, and if you're just starting, you can go for brands such as Klein or commercial electric, which have high-quality stuff that works great. It's unnecessary to buy expensive Fluke tools unless you're a professional.
Even if you're desperate and need to strip a cable using cutters, it's best to wait until you get the proper tools, especially if you're a beginner. Building a solar power system requires doing it right the first time since even a single mistake can cause future problems. Every connection and piece of work in the system needs to be perfect to ensure no issues occur in the future. Therefore, investing in high-quality tools is essential for optimal performance, safety, and reliability of solar power systems.
No.1 Loose Terminals
Loose terminals are one of the most common mistakes beginners make when building solar power systems. Loose terminals can cause fires, melted terminals, and problems with voltage sensing of devices, leading to various issues. To avoid this problem, it's essential to tighten the terminals correctly without over-tightening them.
While many electricians get a good feel for terminal tightness, using Torque screwdrivers to get the exact torque spec is crucial. Terminal tightness is tricky, and high-quality components, properly sized cables, and the best circuit breakers won't matter if they're not tightened correctly. This is especially true for large lithium iron phosphate battery banks that people build with raw cells since they have multiple terminals that all need perfect tightening.
Over time, a terminal can loosen itself up due to expansion and contraction caused by heat and cold. Therefore, it's a good idea to re-torque everything every six months or so to ensure no loose connections. Using a heat camera while inspecting large battery banks with lots of terminals is also useful to check for hot spots indicating loose connections.
When tightening terminals, follow the torque specification on the label. Checking for loose connections by wiggling wires and pulling them out by hand is crucial for ensuring proper terminal tightness in a solar power system. Therefore, always ensure that all terminals are correctly tightened to avoid any potential problems in the future.
Bonus：A Schematic Diagram of RV Solar System
Here's the diagram for 800 Amp Battery + 600W solar system for RV.
This solar power system includes 4 X Litime 12V 200Ah Pluse LiFePO4 battery, which can store the energy. All of Litime's battery are built-in Battery Management System, which can protect you from over current, over charge and discharge, over voltage, short circuit and high temperature. Learn more about Litime from https://www.litime.com/.
Conclusion
In conclusion, building a solar power system is an excellent way to save money and reduce your carbon footprint. However, if you're a beginner, there are several mistakes that you must avoid. By following the tips provided in this article, you can prevent costly and dangerous mistakes when building your first solar power system.
With these tips, you can build a safe, efficient, and reliable solar power system for your home or business.
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