8 AWG vs 10 AWG Solar Wire: Which Size Is Better for PV String Harnesses?

Choosing the correct wire gauge is an important part of photovoltaic system design. The conductor must safely carry the required current while keeping voltage drop, power loss, installation cost and connector compatibility within acceptable limits.

Among the conductor sizes used in photovoltaic systems, 8 AWG and 10 AWG solar wire are often considered when PV string circuits require larger conductors than standard module-level wiring.

So, what is the difference between 8 AWG and 10 AWG solar wire, and which size is better for a PV string harness?

The short answer is that 8 AWG has a larger conductor, lower electrical resistance and greater current-carrying capability than 10 AWG. However, this does not automatically make 8 AWG the better choice. For many PV string harness applications, 10 AWG can provide sufficient electrical performance with lower material cost and easier installation.

The correct selection depends on string current, cable length, voltage drop, temperature, installation conditions and the electrical requirements of the PV system.

8 AWG vs 10 AWG Solar Wire at a Glance

The American Wire Gauge system works in reverse: the smaller the AWG number, the larger the conductor.

Therefore, 8 AWG is larger than 10 AWG.

*Nominal solid-conductor equivalent diameter. Actual stranded photovoltaic conductor construction will vary.

The conductor area of 8 AWG is approximately 59% larger than that of 10 AWG, which is why it can offer lower resistance and lower voltage drop over the same cable length.

Is 8 AWG Bigger Than 10 AWG?

Yes.

In the AWG system:

8 AWG > 10 AWG > 12 AWG

in terms of physical conductor size.

This can initially be confusing because the numerical sequence moves in the opposite direction. A lower AWG number represents a larger conductor.

For photovoltaic applications, moving from 10 AWG to 8 AWG increases the conductor cross-sectional area from approximately 5.26 mm² to 8.37 mm².

That larger conductor directly affects resistance, voltage drop and current-carrying performance.

What Is the Main Difference Between 8 AWG and 10 AWG Solar Wire?

The main difference is conductor size.

Because 8 AWG contains more conductive material, it generally has:

• lower electrical resistance

• lower voltage drop

• lower resistive power loss

• greater current-carrying capability

10 AWG, however, requires less conductor material and is generally:

• lighter

• more flexible

• easier to route

• less expensive

• suitable for many conventional PV string circuits

Therefore, the decision is not simply about choosing the largest wire possible. The objective is to select a conductor that satisfies the electrical design without unnecessarily increasing system cost.

8 AWG vs 10 AWG Resistance

Electrical resistance is one of the most important differences between the two conductor sizes.

For copper conductors at approximately 20°C, typical DC resistance values are roughly:

Actual resistance depends on conductor construction, strand configuration, conductor material and operating temperature.

Because 8 AWG has lower resistance, it produces less voltage drop when carrying the same current over the same distance.

This becomes increasingly important as PV cable runs become longer.

8 AWG vs 10 AWG Voltage Drop

Voltage drop occurs because every conductor has electrical resistance.

A simplified DC voltage-drop relationship is:

Voltage Drop = Current × Circuit Resistance

As either current or cable length increases, voltage drop increases.

Increasing conductor size reduces resistance and therefore helps control voltage drop.

For example, suppose a PV circuit carries the same current over the same distance.

A 10 AWG conductor will normally produce more voltage drop than an 8 AWG conductor because its resistance is higher.

This means 8 AWG becomes increasingly attractive for:

• longer PV cable runs

• higher-current circuits

• systems with stricter voltage-drop targets

• large commercial PV arrays

• utility-scale photovoltaic projects

However, for relatively short cable runs, the voltage-drop difference may not justify the additional cost of using 8 AWG.

Does 8 AWG Carry More Current Than 10 AWG?

Generally, yes.

Because 8 AWG has a larger conductor, it normally has a higher allowable ampacity than 10 AWG under comparable operating conditions.

However, wire gauge alone does not determine allowable current.

PV cable ampacity can also depend on:

Conductor Material

Copper and aluminum do not have the same electrical conductivity. A copper conductor and an aluminum conductor with the same AWG size therefore cannot automatically be treated as equivalent.

Insulation Temperature Rating

PV wire may be manufactured using insulation systems with different temperature ratings.

Higher insulation temperature capability can affect conductor ampacity calculations, but terminal ratings and applicable electrical codes must also be considered.

Ambient Temperature

Solar installations can expose cables to high temperatures, especially on rooftops or in direct sunlight.

Higher ambient temperatures may require ampacity correction factors.

Number of Conductors

Multiple conductors installed together can retain heat.

Depending on the installation method and applicable electrical standard, conductor bundling may require current derating.

Installation Method

A cable installed in free air behaves differently thermally from a cable installed in conduit, cable tray, enclosed raceway or another restricted environment.

For this reason, asking simply “How many amps can 8 AWG solar wire carry?” does not always have one universal answer.

The allowable current should be calculated according to the applicable PV system standard and installation requirements.

When Should You Use 10 AWG Solar Wire?

10 AWG is widely considered for PV string wiring because it offers a practical balance between electrical performance, cable size and cost.

It may be suitable when:

The String Current Is Within the Cable Design Limit

If the required circuit current can be safely carried by 10 AWG after all necessary adjustment and correction factors are applied, increasing to 8 AWG may not be necessary.

Cable Runs Are Relatively Short

For shorter cable runs, voltage drop may already be sufficiently low with 10 AWG.

Using a larger conductor would then provide limited electrical benefit.

Installation Space Is Limited

10 AWG has a smaller overall conductor size, which can make routing easier through cable management systems, junction boxes and connectors.

Project Cost Is Important

Copper is a significant component of photovoltaic cable cost.

Using a properly sized 10 AWG conductor instead of unnecessarily specifying 8 AWG can reduce conductor material usage across large PV projects.

For large solar installations involving many kilometers of cable, even small conductor-size differences can significantly affect total cable cost.

When Should You Consider 8 AWG Solar Wire?

8 AWG becomes more attractive when the electrical requirements begin to exceed what 10 AWG can efficiently provide.

Longer PV Cable Runs

Longer conductors create greater total circuit resistance.

Increasing from 10 AWG to 8 AWG can help reduce voltage drop and energy loss.

Higher Circuit Current

Some PV system configurations combine multiple strings or use circuits carrying higher current than conventional module interconnections.

Larger conductors may therefore be required.

Lower Voltage-Drop Targets

Some system designers intentionally specify low voltage-drop limits to improve energy delivery.

In these applications, conductor sizing may be based not only on ampacity but also on electrical efficiency.

Large Commercial and Utility-Scale PV Systems

Large photovoltaic installations can contain long DC cable routes between arrays, combiner equipment and power-conversion equipment.

In these applications, conductor resistance becomes increasingly important.

8 AWG vs 10 AWG for PV String Harnesses

A PV string harness connects multiple photovoltaic strings or modules into a predetermined electrical configuration.

The conductor size used in the harness must be selected according to the actual electrical architecture.

10 AWG may be suitable for many conventional PV string harness applications where:

• string current is moderate

• cable runs are controlled

• voltage drop remains acceptable

• connectors support the selected conductor size

8 AWG may be considered when:

• multiple strings increase circuit current

• harness branches become longer

• lower circuit resistance is required

• voltage-drop targets are stricter

Therefore, conductor sizing should be based on the electrical requirements of the complete harness rather than selecting an AWG size independently.

Can You Replace 10 AWG Solar Wire With 8 AWG?

Electrically, using a larger conductor can often reduce resistance, but replacing 10 AWG with 8 AWG is not simply a matter of changing the cable.

Several components must be checked.

Connector Compatibility

PV connectors are designed for specific conductor ranges.

A connector designed for 10 AWG may not necessarily accept an 8 AWG conductor.

The conductor cross-sectional area, insulation diameter and crimp contact must all be compatible.

Junction Box Compatibility

Cable entry dimensions and terminal capacity must also support the larger conductor.

Crimping Tools

Different conductor sizes may require different crimp dies or crimp settings.

Improper crimping can increase contact resistance and create reliability problems.

Bend Radius

Larger cables may require more installation space and a larger minimum bending radius.

For custom PV string harness manufacturing, these mechanical considerations are just as important as conductor ampacity.

Is 8 AWG Better Than 10 AWG for Solar Panels?

Not necessarily.

8 AWG offers superior electrical performance in terms of resistance and voltage drop, but that does not mean every solar installation benefits from it.

For example, if a PV string requires only a short cable run and 10 AWG already satisfies:

ampacity requirements, voltage-drop limits, thermal requirements and applicable electrical codes,

changing to 8 AWG may only increase cable cost and installation complexity.

A better question is:

Which conductor size provides the required electrical performance for the specific PV circuit?

For some systems, that will be 10 AWG.

For others, 8 AWG may be the more appropriate choice.

Does Thicker Solar Wire Improve Efficiency?

A larger conductor reduces resistance.

Lower resistance means lower resistive power loss.

Electrical conductor loss can be expressed approximately as:

Power Loss = I²R

where:

I = currentR = conductor resistance

Because current is squared in this relationship, conductor losses become increasingly important as current rises.

Reducing resistance by increasing conductor size can therefore improve electrical efficiency.

However, system designers must balance this efficiency improvement against the increased cost of the larger conductor.

The technically largest wire is not necessarily the economically optimal wire.

How to Choose Between 8 AWG and 10 AWG Solar Wire

For PV string harness design, consider at least the following factors.

1. Maximum Circuit Current

Determine the expected maximum current and apply the appropriate design requirements and safety factors.

2. Cable Length

Calculate the complete current path rather than considering only one physical cable segment.

Longer circuits generally benefit more from larger conductors.

3. Voltage Drop

Calculate expected voltage drop under operating conditions.

If 10 AWG produces excessive voltage drop, 8 AWG may provide a practical solution.

4. Operating Temperature

Consider ambient temperature, rooftop exposure, cable grouping and installation environment.

5. Connector Range

Verify that connectors, terminals, junction boxes and crimp contacts support the selected conductor.

6. Cable Certification

PV cable should comply with the standards required by the target market and project.

Depending on the application, specifications may involve requirements such as UL 4703, IEC 62930 or EN 50618, together with project-specific electrical codes.

7. Total Installed Cost

Do not compare only cable price per meter.

A larger conductor may increase cable and connector costs, while a smaller conductor may result in greater energy losses.

The best conductor size should therefore be selected based on overall system performance and project economics.

8 AWG vs 10 AWG: Which Should You Choose?

Neither conductor is universally better.

Choose 10 AWG solar wire when its ampacity and voltage-drop performance comfortably satisfy the PV string harness requirements. It can provide a cost-effective solution for many standard solar string applications.

Consider 8 AWG solar wire when the system involves longer cable runs, higher current or stricter voltage-drop requirements.

For engineered PV string harnesses, conductor sizing should ultimately be based on:

current + cable length + voltage drop + temperature + installation method + connector compatibility.

This approach avoids both undersizing, which can create electrical and thermal problems, and unnecessary oversizing, which increases project cost.

FAQ

Is 8 AWG bigger than 10 AWG?

Yes. In the American Wire Gauge system, a lower AWG number represents a larger conductor. 8 AWG has a nominal conductor area of approximately 8.37 mm², while 10 AWG is approximately 5.26 mm².

Is 8 AWG better than 10 AWG for solar?

8 AWG has lower resistance and generally provides greater current-carrying capability and lower voltage drop. However, 10 AWG may be more economical when it already satisfies the circuit's ampacity and voltage-drop requirements.

Can I use 8 AWG wire for solar panels?

Yes, 8 AWG can be used in appropriate photovoltaic applications when the cable construction, electrical rating, connectors and certifications are suitable for the system. The conductor size should be verified through the electrical design.

Can I use 10 AWG wire for solar panels?

Yes. 10 AWG solar wire is commonly considered for PV applications when its ampacity and voltage-drop performance satisfy the system requirements.

Does 8 AWG have less voltage drop than 10 AWG?

Yes. For the same conductor material, cable length and current, 8 AWG normally produces less voltage drop because its electrical resistance is lower.

How many amps can 8 AWG solar wire carry?

There is no single ampacity that applies to every 8 AWG solar cable installation. Allowable current depends on conductor material, insulation temperature rating, ambient temperature, installation method, cable grouping and the electrical code or standard being used.

How many amps can 10 AWG solar wire carry?

The allowable ampacity of 10 AWG also depends on the cable specification and installation conditions. The conductor should be sized using the applicable ampacity tables together with any required temperature and installation correction factors.

What AWG is best for a PV string harness?

There is no universal best AWG size. 10 AWG may be suitable for many conventional PV string harnesses, while 8 AWG may be preferred for longer runs or higher-current circuits. The correct size should be determined by current, voltage drop, cable length and installation conditions.

Can I replace 10 AWG with 8 AWG?

A larger 8 AWG conductor may electrically replace 10 AWG in some designs, but connector size, terminal capacity, insulation diameter, crimp contacts and installation space must also be verified before making the change.

Is thicker solar wire always better?

No. Thicker wire reduces resistance and voltage drop, but it also increases cable size, weight and cost. Solar conductors should be sized according to the actual electrical requirements rather than simply selecting the largest available wire.