Sunhub/Source

    Procurement planning tools

    Solar Power Calculator Suite

    Convert watts to amps, amps to watts, and check voltage drop before you specify equipment. These are the unit conversions installers and EPCs run while sizing strings, inverters, conductors, and balance of system for a project.

    Enter your values and the results update instantly — nothing is stored. When your numbers are settled, post one request and let verified suppliers quote against the same specification.

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    Watts to Amps calculator

    Convert power to current to size conductors, fuses, breakers, and combiner boxes before you request quotes. Formula: A = W / V (DC), A = W / (V x PF) (AC single-phase), A = W / (√3 x V x PF) (AC three-phase).

    W
    V

    Current

    104.17 A

    Amps to Watts calculator

    Convert current to power when a datasheet lists amperage but your system sizing or RFQ needs watts. Formula: W = A x V (DC), W = A x V x PF (AC single-phase), W = √3 x A x V x PF (AC three-phase).

    A
    V

    Power

    720 W (0.72 kW)

    Voltage drop calculator

    Estimate conductor voltage drop over a one-way run so your wire and BOS line items are specified correctly in the request. NEC recommends keeping branch-circuit drop at or under 3%, and total feeder plus branch drop at or under 5%.

    A
    V
    ft

    Voltage drop

    7.9 V (3.29%)

    Above the 3% guideline — consider a larger conductor. Voltage at load: 232.1 V.

    Results are estimates for planning and procurement use only. Confirm all conductor sizing, overcurrent protection, temperature correction, and conduit-fill derates against the National Electrical Code and a licensed engineer before purchase or installation.

    What to include in a solar RFQ after sizing

    Once the conversions are done, suppliers need a handful of concrete values to quote accurately on the first pass.

    • PV modules: wattage per module, cell technology, module quantity or total kW/MW, Imp and Vmp, certifications.
    • Inverters: AC output power, nominal AC voltage and phase, MPPT count, input voltage window, grid code.
    • Batteries: chemistry, usable kWh, nominal DC voltage, continuous discharge current, AC or DC coupled.
    • Wire and BOS: conductor size and material, run lengths, combiner and disconnect ampacity, connector type.

    Solar calculator FAQs

    How do you convert watts to amps?

    For DC circuits, divide watts by volts: A = W / V. For AC single-phase, divide by voltage times power factor: A = W / (V x PF). For AC three-phase, use A = W / (1.732 x V x PF). A 5,000 W load at 48 V DC draws about 104 A.

    How do you convert amps to watts?

    Multiply amps by volts: W = A x V for DC. For AC single-phase, multiply by power factor as well, and for three-phase multiply by 1.732 and the power factor. A module producing 18 A at 40 V delivers about 720 W.

    What power factor should I use for solar inverters?

    Most grid-tied PV inverters are specified at unity (1.0) power factor, though utility interconnection rules often require operation between 0.90 and 0.95 leading or lagging. Use the value in the inverter datasheet or the utility requirement for your interconnection.

    What is an acceptable voltage drop for a solar array?

    The NEC recommends 3% or less on a branch circuit and 5% or less combined across feeders and branch circuits. Many designers target 2% on DC string runs to preserve production over the life of the system.

    Why do these numbers matter for a solar RFQ?

    Suppliers quote faster and more accurately when the request states real electrical values: string current, inverter AC output, conductor size, and run lengths. Converting units before you post the request removes a round of clarification emails.

    Are these calculators a substitute for engineered design?

    No. They are planning aids for procurement and preliminary sizing. Final conductor sizing, overcurrent protection, and temperature and conduit-fill derates must be confirmed by a licensed engineer against the applicable code.

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