Designing a solar PV system isn’t just about placing panels on a roof — it’s about delivering maximum efficiency, longevity, and compliance, all while keeping the client’s budget in check.

At One Place Solar, our recent Texas project — a 7.6kW rooftop system using Tesla inverters and Longi 400W panels — gave us plenty of insights. Whether you’re a beginner or an experienced solar designer, here are key takeaways and tips from this successful installation that you can apply to your next project.

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🔧 1. Design with Premium Equipment in Mind — Without Overengineering

Tip: Know how to integrate premium components like Tesla inverters and Longi panels without overcomplicating the system.

Why it matters: High-end doesn’t mean hard-to-install. We used one Tesla 7.6kW inverter and 19 Longi 400W modules. The system was simple, clean, and extremely effective.

✅ What to do:

• Understand how to size inverter-to-module ratio properly.
• Familiarize yourself with Tesla’s monitoring and rapid shutdown integration to simplify compliance.
• Plan your strings efficiently — we used two smart strings (10+9) for layout flexibility.

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📐 2. Balance Aesthetics and Output with Smart Stringing

Tip: String layout affects both efficiency and roof utilization.

In this project, we had two roof sections at different azimuths. To optimize, we created:

• 1 string of 10 panels on Roof #1
• 1 string of 9 panels on Roof #2

This avoided shading, matched orientation, and balanced voltage outputs across strings.

✅ Pro Tip: Always use simulation tools (like Helioscope or Aurora) to predict real-world output from different roof slopes and orientations.

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🛠️ 3. Use Racking Systems That Engineers Love

Tip: Go with code-compliant, proven racking systems like K2 CrossRail with Splice Foot XL.

Why we used it:

• Meets UL standards
• Fast to install
• Minimal roof penetration
• Secure in high-wind zones like Texas

✅ Design Consideration: Always align your rafter spacing with racking options. In our case, 2″x6″ rafters at 24″ O.C. worked perfectly with 48″ attachment spacing.

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⚡ 4. Don’t Underestimate the Electrical Panel & Interconnection

Tip: Design with utility requirements and NEC codes in mind from day one.

In this project:

• We provided a 40A breaker on a 200A busbar (compliant with the 120% rule).
• We added a visible, lockable AC disconnect within 10 feet of the meter — a requirement from the local utility (LP&L).

✅ Your Checklist:

• Confirm busbar rating before selecting breaker size.
• Follow NEC 705.12 for load-side connections.
• Label everything — better safe than delayed inspection.

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🔒 5. Design for Safety First: Placards, Setbacks & Shutdowns

Tip: Always include rapid shutdown, clear labeling, and fire setbacks.

This system was:

• Fully placarded as per NEC 690.54, 705.12, 690.13(G)
• Shutdown compliant
• Installed with 36″ fire setbacks for first responders

✅ Reminder: Include labeling on DC conduit, inverters, junction boxes, and service panels. Keep a library of NEC-compliant labels ready in your CAD or design software.

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📊 6. Make Your BOM Count

Tip: Your Bill of Materials (BOM) isn’t just for procurement — it’s your signature as a designer.

We included:

• Every nut, bolt, rail, and lug
• Two branch terminators
• High-quality EMT conduits rated for wet location
• UV-resistant wire ties

✅ Pro Tip: A detailed BOM shows professionalism, ensures no missed items on-site, and improves approval rates from AHJs.

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🏆 7. Design With the AHJ in Mind, Always

Every Authority Having Jurisdiction (AHJ) is different. This project had to follow:

• 2015 IBC / IRC / IFC
• NEC 2014 (Lubbock-specific)
• Local fire codes
• Utility rules for LP&L

Tip: Research your AHJ codes before designing.
Bonus Tip: Build a quick checklist template per city or county to speed up future projects.

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✍️ Final Thoughts for Designers

A well-designed solar project blends engineering excellence with on-site practicality. It anticipates code requirements, makes installers’ jobs easier, and — most importantly — delivers long-term value for the client.

From Tesla inverters to racking to proper interconnection, this Texas project is a reminder that smart design isn’t just technical — it’s strategic.

Ready to level up your design game?
Keep learning, stay code-aware, and prioritize performance without overcomplicating.

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Want help with permit sets, AHJ-ready designs, or system optimization?
📩 Reach out to One Place Solar — where design meets execution.