Common Mistakes in Solar Cable Selection and How They Affect Power Loss

Choosing the right cable for a solar system directly affects how much power you actually use. The wrong choice can cause energy loss, safety risks, and long-term damage. This article explains the most common mistakes in solar cable selection and how they reduce performance. You’ll also learn how conductor type, insulation, and voltage drop affect efficiency, plus how to avoid costly errors from the start.

By the end, you’ll understand how proper cable choices improve energy flow, protect equipment, and extend system life.

Why Cable Choice Matters in Solar Systems

A solar system does not fail only because of panels or inverters. Many problems start with wiring. Cables carry direct current from panels to other components. If they are undersized or poorly protected, energy is lost as heat before reaching the load.

Even small losses add up over the years. That means lower output and higher maintenance costs. Understanding the basics helps prevent these issues early.

Mistake 1: Ignoring Cable Size and Current Flow

How cable size affects power loss

Cable size controls how much current can pass safely. If the conductor is too small, resistance increases. Higher resistance causes a voltage drop, which reduces usable power.

This issue often appears in long runs between panels and combiner boxes. The wrong cable size can waste energy daily without visible signs.

Simple sizing rule for beginners

Longer distance means larger cross-section. Higher current also requires thicker conductors. Always calculate based on distance, current, and system voltage before installation.

Mistake 2: Overlooking Voltage Drop in DC Systems

Why voltage drop matters more in solar

Solar systems use direct current. DC systems experience higher losses over distance compared to AC. Even a small voltage drop can reduce panel output. Industry guidance suggests keeping voltage drop under 2–3% for DC circuits. Exceeding this limit directly lowers energy harvest.

According to the U.S. National Renewable Energy Laboratory, poor conductor selection is a leading cause of PV efficiency loss.

Mistake 3: Choosing the Wrong Conductor Material

Copper versus alternatives

Copper remains the preferred conductor due to lower resistance and better heat control. Aluminum costs less but needs larger diameters to match performance.

A tinned copper cable adds corrosion resistance. This matters in outdoor and humid environments where oxidation increases resistance over time.

Why tinning helps

Tin coating protects copper strands from moisture and chemical exposure. This keeps conductivity stable across decades of service.

Mistake 4: Using Inappropriate Insulation Materials

Insulation is not just a cover

Insulation protects conductors from heat, UV radiation, and weather. Poor insulation cracks over time, exposing conductors and increasing risk.

Modern systems often use XLPE cable insulation. Cross-linked polyethylene handles higher temperatures and resists UV damage better than PVC.

Advanced insulation example

TOSUN solar cables use electron-beam cross-linked insulation. This process improves heat resistance and mechanical strength without chemical additives.

Mistake 5: Treating All PV Cables the Same

Not all PV cable types serve the same role

Some cables are designed for fixed runs. Others work better as an extension cable for solar panel connections. Mixing them incorrectly causes stress at joints and connectors.

Each application needs proper flexibility, insulation thickness, and connector compatibility.

Mistake 6: Ignoring Environmental Conditions

Outdoor exposure changes everything

Sunlight, rain, heat, and cold all affect cable life. UV exposure alone can degrade standard insulation within years.

Cables routed on rooftops or open fields need materials tested for long-term outdoor use. Temperature swings also affect resistance and expansion.

Mistake 7: Poor Termination and Connector Choices

Connectors affect performance, too

Loose or incompatible connectors create resistance points. These spots heat up and waste energy.

Proper crimping and matched connectors reduce losses and improve system stability. MC4-compatible designs are common in modern installations.

How Better Cable Choices Improve Performance

Correct cable selection leads to:

• Lower energy loss
• Stable current flow
• Longer system life
• Fewer maintenance issues

High-grade insulation and proper conductor size reduce stress on the system and improve safety.

How Quality Design Reduces Long-Term Losses

Cables designed for solar use focus on conductor purity, insulation strength, and thermal stability. These factors work together to reduce resistance and aging effects.

TOSUNLUX designs PV cable products using tinned copper conductors and advanced insulation systems. This approach supports stable performance in harsh conditions while meeting international standards.

You can explore their collection here:
https://www.tosunlux.eu/category/solar-pv-connector-pv-cable/#mainbox

Conclusion: Choose Smart, Save Power

Good cable choices protect energy output and system lifespan. Understanding materials, insulation, and sizing helps avoid hidden losses. If you want components designed for real solar conditions, explore the TOSUNLUX collection of PV connectors and cables. The right choice today prevents losses tomorrow.

Domande frequenti 

1. What causes power loss in solar wiring?

Power loss comes from resistance, long distances, small conductors, and poor connections. Heat turns wasted energy into loss.

2. How do I choose the correct cable size?

Base it on current, distance, and system voltage. Larger systems and longer runs need thicker conductors.

3. Is XLPE insulation better for solar use?

Yes. XLPE handles higher temperatures and resists UV exposure better than standard insulation materials.

4. Why is tinned copper used?

Tin coating protects copper from corrosion. This keeps resistance stable in outdoor environments.

5. Can extension cables reduce system efficiency?

Yes. Poor-quality extension cables add resistance and increase voltage drop if not sized correctly.