WireGaugeCalc Free calculator · NEC cited · works offline
SolarEdge DC Voltage Drop
solaredge dc voltage drop is quick to check with WireGaugeCalc.
The calculator takes the string voltage, the one-way run length, and the conductor size, then returns the drop so you can keep the DC side inside the usual guideline.
You see whether the gauge holds or needs to go up before the inspection.
Open the calculatorUses Vd = (phase factor × K × I × L) / circular mils, K = 12.9 copper, 21.2 aluminum. Field aid only, verify against the current NEC and your local authority having jurisdiction.
Keeping The DC Run Inside The Guideline
Voltage drop grows with run length, so a long roof-to-inverter DC run can lose more than the common 2 to 3 percent target.
The calculator compares your drop to that guideline, since holding it low protects optimizer performance on the SolarEdge string.
Copper and aluminum return different numbers, because aluminum has higher resistance for the same gauge.
What Drives The DC Drop
The calculator works from the values that set the loss:
- String voltage and current
- One-way run length
- Conductor gauge and material
- Copper versus aluminum resistance
- Target percent drop, often 2 to 3 percent
One app for every NEC calculation
WireGaugeCalc keeps the calculations you reach for most in one place:
- Voltage drop and wire sizing for any run
- Conduit fill for EMT, PVC, and RMC
- Box fill and junction box sizing
- Ampacity and temperature derating
- Motor circuit and load calculations
- Conduit bend offsets and saddles
Built for the field, works offline
The whole app runs on your phone, so it keeps working in a basement, an attic, or a job site with no signal.
There is no account to create and nothing to load. Open it, run the number, and get back to work.
- No signup and no signal needed
- Answers in a tap, not a spreadsheet
- Same tool on phone, tablet, and desktop
Every result cites the NEC article
Each answer shows the table or formula it came from, so you can check the method and learn the code as you go.
That makes the app useful on the job and during exam prep, since the reasoning is right next to the number.
Switch the code year your job runs on
Jurisdictions adopt the NEC at different times, so you can match the calculation to the code in force:
- NEC 2017, 2020, and 2023 tables
- Copper and aluminum conductors
- 60, 75, and 90 degree C terminations
- Single-phase and three-phase systems
Run the number, then get back to work
Stop flipping through a paper book or hopping between calculator sites. Enter your values, read the code-cited answer, and move on. Free to use, no signup.
Open the calculatorFrequently asked questions
What is a reasonable DC voltage drop target for a SolarEdge string?
Many installers hold the DC run to 2 percent or less so the optimizers and inverter see clean voltage. Confirm any project specific target against the current NEC and your local authority having jurisdiction.
Does upsizing the PV wire fix high drop?
Yes, a larger gauge lowers resistance and cuts the drop on the same run. The calculator shows the next size needed to meet your target.
Is WireGaugeCalc free to use?
Yes. Every calculator is free to run with no signup. A paid tier adds saved projects, PDF reports, and extra code years, but the core math stays free.
Does it work without internet?
Yes. The app runs on your device, so it keeps working with no signal on a job site, in a basement, or in an attic.
Are the results code accurate?
Results follow published NEC tables and standard formulas, and each answer shows the article it came from. It is a field aid, not a stamp of approval, so verify against the current code and your local authority before you wire anything.
Which NEC code year does it use?
You can switch between NEC 2017, 2020, and 2023, since jurisdictions adopt the code at different times. Pick the year your job runs on.