Off-Grid Solar Installation Series: Solar Panels Setup

Welcome to the third video in our off-grid solar installation series. This series is designed to take you step-by-step through the entire process of designing, procuring, and installing a new solar system. In the previous video, we covered batteries. In this installment, we focus on solar panels. We’ll discuss the design rationale, connect the panels, and show you how it all works.

 

Designing the Solar Panel Array

Matching Panels to Battery Bank

When designing your solar panels or specifying your solar panel array, the design should match the battery bank. This design is based on several factors:

• Sun hours available in your area
• Size of the battery bank
• Recharge rate goals

 

I wanted our battery bank to recharge within two hours in the morning to keep it topped off. With four to five sun hours a day, we designed a 5200-watt array.

 

Designing for Expansion

The array charges our batteries in two to three hours on a sunny day and allows the battery bank to last three and a half to four days without recharge. There are 18 total panels, each producing 290 watts from SolarWorld. Each panel has about a 17.5% efficiency rating, putting out 34-35 volts and 7.5-8 amps.

We strung the panels in series, increasing the voltage while keeping the amperage the same. Each string of three panels produces about 100 volts and eight amps. These strings are then connected in parallel with two other strings. There are nine panels in an array, and we have two arrays.

Each array produces 2,500 watts at peak sun. The arrays connect to their own charge controllers, allowing for future expansion. We can add two more strings to each array, increasing the system’s capacity to 8,000 watt-hours, which is more than sufficient for our needs.

 

Building and Installing the Racks

Temporary Installation

I spent about a week building racks, initially using nine-foot pallets. After constructing three racks, I switched to simpler pallets, realizing the original method was time-consuming. These racks are a temporary solution while we are at the camp. When we move to the house, I plan to set these up on a permanent ground mount or a top-of-pole mount.

 

Wiring the Panels

I completed most of the wiring but haven’t connected each panel together yet. The next step is to connect the three panels in series, run a voltmeter test, and ensure everything is functioning correctly.

 

Safety Measures

Always cover your panels with a tarp during daytime work to reduce the voltage and ensure safety.

 

Connecting the Panels

Making the Cables

I created cables from the combiner box to each string. Now, I’ll plug them in:

• Positive of the first panel to the negative of the second panel
• Positive of the second panel to the negative of the third panel
• Positive of the third panel back through to the combiner box

 

Testing the Voltage

With the panels connected, I’ll use a voltmeter to test the output:

1. First String: 85.6 volts (a bit low, possibly due to shade)
2. Second String: 110 volts (good output)
3. Third String: Not connected yet, but shows some voltage

Next, I’ll connect the third string, switch on the breakers, and we should have power up to the house.

 

 

Setting Up the Combiner Box

Inside the Combiner Box

Here’s a look inside the combiner box for the nine-panel array:

• Positive and negative connections from panels to the combiner box
• Common negative bus bar
• 4-gauge cable for positive and negative connections to the inverter
• Ground wires for each panel bonded together and connected to a ground stake
• Surge protection devices (SPD) for voltage clamping in case of lightning issues

 

Testing the Combined Strings

With the tarp removed, we test the voltage of the combined strings to ensure proper output. This step is crucial for confirming the system is operating as expected.

 

Selecting Solar Panels

Evaluating Panel Performance

When selecting solar panels, manufacturers publish specs under standard test conditions (STC), including open circuit voltage and current. Generally, you can expect about 80% of the rated output in real-world conditions. Our SolarWorld panels produce exactly what they promise, making them a reliable choice.

 

Charge Controllers and Battery Bank

Our system uses Midnight Solar Classic 150 charge controllers, known for their durability and performance over 20 years. Each can handle 96 amps. The charging current for our batteries is 34 amps each, and with six batteries in parallel, that totals 204 amps.

Using two Classic 150s, each rated at 96 amps, is ideal for our configuration. Currently, we’re utilizing about 60% of the charge controller capacity. As we add more panels, we can scale up to 12 more, maximizing our system’s potential.

 

Recommended Resources

AltE Store

We sourced all our components from AltE Store (altEstore.com). They offer excellent customer support, helping validate our design and providing a library of technical information. For DIY enthusiasts, their YouTube channel is a valuable resource.

 

Conclusion

That concludes our setup for the solar panel array. Next, we’ll cover the combiner box setup, from unboxing to final installation. Stay tuned for the next video in our off-grid solar installation series. Thanks for watching!