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EV Charging from Solar

Time to charge an EV battery from a solar array.

Design

Inputs (SI units)

Usable capacity of the vehicle's traction battery pack.

State of charge at the start of the charging session.

Desired state of charge at the end of the session — must exceed starting SOC.

AC-DC (or DC fast-charge) conversion efficiency including cabling and onboard charger losses.

Rated output power of the EVSE/charge point delivering the session.

Maximum AC charging power the vehicle's onboard charger can accept — caps the effective charger power.

Forecast/measured solar energy produced during the charging window, available for direct EV charging.

Vehicle's real-world energy consumption, used to translate added energy into driving range.

Results

Charging time
5.41 h
Required input energy
40 kWh
Solar-charged share
38 % (15 kWh)
Grid import needed
25 kWh
Surplus PV exported
0 kWh
Range added
225 km
✓ PASS — Charger power 7.4 kW is within the vehicle's onboard charger limit 11 kW.
⚠ WARNING — Only 38% of this charge is solar-covered — 25 kWh will be imported from the grid.
✓ PASS — Charging time 5.41 h is a practical single session.

Engineering Recommendations

  • →Schedule charging to overlap peak PV production hours to maximise the solar-covered share.
  • →Where the vehicle supports it, use a smart/solar-diversion charger to modulate power with available PV in real time.
  • →Engineering-grade preliminary calculation. Final design must be verified against project-specific site conditions, manufacturer datasheets, applicable standards and utility requirements.

Detailed Calculation Log

SOC 20% → 80% requires 36 kWh into the pack.
Charger loss fraction 10% -> input energy 40 kWh.
Effective charger power 7.4 kW (OBC-limited: false).
Solar covers 38% of this session; PV available window energy = 15 kWh.

Save & Load Project

Designs are stored privately in this browser — nothing is uploaded.

Engineering Formula

  • E_needed = Cap / η
  • Time = E_needed / P_solar

Assumes constant PV output over the charging window. Real charging follows a CC-CV curve; add 10–15% margin.

Step-by-step Calculation

  1. 1.SOC deltaTarget − Start60 %
  2. 2.Required battery energyCap × ΔSOC36 kWh
  3. 3.Required input energyE_batt / η_charger40 kWh
  4. 4.Charging lossesE_input − E_batt4 kWh
  5. 5.Effective charger powermin(charger, OBC limit)7.4 kW
  6. 6.Solar sharemin(PV available, E_input)15 kWh
  7. 7.Grid importE_input − solar share25 kWh
  8. 8.Charging timeE_input / P_effective5.41 h
  9. 9.Range addedE_batt×1000 / Wh_per_km225 km

How to use this calculator: EV Charging from Solar

Time to charge an EV battery from a solar array. The example below is calculated by this page's real engine from the displayed inputs.

  1. 1Confirm that the EV Charging from Solar matches the quantity or design check you need.
  2. 2Enter EV battery capacity, Starting SOC, and Target SOC using the units printed beside each field.
  3. 3Check every value before calculating, especially decimal points and measurement units.
  4. 4Calculate, then follow the substituted equations in the worked example and compare the result with any stated limit.
  5. 5Read the assumptions, warnings and cited references before using the result for a financial, medical or engineering decision.

Input guide and example values

Use values from the same measurement basis and time period. Conditional fields appear only when the related option is selected.

InputExample valueWhy it matters
EV battery capacity60 kWhUsable capacity of the vehicle's traction battery pack.
Starting SOC20 %State of charge at the start of the charging session.
Target SOC80 %Desired state of charge at the end of the session — must exceed starting SOC.
Charger conversion efficiency90 %AC-DC (or DC fast-charge) conversion efficiency including cabling and onboard charger losses.
Charger power7.4 kWRated output power of the EVSE/charge point delivering the session.
Vehicle onboard charger limit11 kWMaximum AC charging power the vehicle's onboard charger can accept — caps the effective charger power.
PV energy available in charging window15 kWhForecast/measured solar energy produced during the charging window, available for direct EV charging.
Vehicle consumption160 Wh/kmVehicle's real-world energy consumption, used to translate added energy into driving range.

Formula inputs & variables for EV Charging from Solar

These are the named quantities used by this calculator. When the source formula does not define a mathematical symbol, OneCalcApp keeps the real input label instead of inventing one.

Variable / inputUnitMeaning in this calculation
EV battery capacitykWhUsable capacity of the vehicle's traction battery pack.
Starting SOC%State of charge at the start of the charging session.
Target SOC%Desired state of charge at the end of the session — must exceed starting SOC.
Charger conversion efficiency%AC-DC (or DC fast-charge) conversion efficiency including cabling and onboard charger losses.
Charger powerkWRated output power of the EVSE/charge point delivering the session.
Vehicle onboard charger limitkWMaximum AC charging power the vehicle's onboard charger can accept — caps the effective charger power.
PV energy available in charging windowkWhForecast/measured solar energy produced during the charging window, available for direct EV charging.
Vehicle consumptionWh/kmVehicle's real-world energy consumption, used to translate added energy into driving range.

How the EV Charging from Solar works

The EV Charging from Solar uses EV battery capacity, Starting SOC, Target SOC, Charger conversion efficiency, Charger power, Vehicle onboard charger limit, PV energy available in charging window, and Vehicle consumption to calculate Charging time, Required input energy, Solar-charged share, Grid import needed, Surplus PV exported, and Range added. Its engine applies E_needed = Cap / η; the worked values below come from that same live calculation rather than a separately typed example.

With EV battery capacity 60 kWh, Starting SOC 20 %, Target SOC 80 %, Charger conversion efficiency 90 %, Charger power 7.4 kW, Vehicle onboard charger limit 11 kW, PV energy available in charging window 15 kWh, and Vehicle consumption 160 Wh/km, the main worked-example result is Charging time = 5.41 h.

How each EV Charging from Solar input is used

EV battery capacity

The EV Charging from Solar worked example uses EV battery capacity = 60 kWh. This value is passed directly into the calculation, with an allowed minimum 1. Usable capacity of the vehicle's traction battery pack.

Starting SOC

The EV Charging from Solar worked example uses Starting SOC = 20 %. This value is passed directly into the calculation, with an allowed minimum 0 and maximum 100. State of charge at the start of the charging session.

Target SOC

The EV Charging from Solar worked example uses Target SOC = 80 %. This value is passed directly into the calculation, with an allowed minimum 1 and maximum 100. Desired state of charge at the end of the session — must exceed starting SOC.

Charger conversion efficiency

The EV Charging from Solar worked example uses Charger conversion efficiency = 90 %. This value is passed directly into the calculation, with an allowed minimum 70 and maximum 98. AC-DC (or DC fast-charge) conversion efficiency including cabling and onboard charger losses.

Charger power

The EV Charging from Solar worked example uses Charger power = 7.4 kW. This value is passed directly into the calculation, with an allowed minimum 0.5. Rated output power of the EVSE/charge point delivering the session.

Vehicle onboard charger limit

The EV Charging from Solar worked example uses Vehicle onboard charger limit = 11 kW. This value is passed directly into the calculation, with an allowed minimum 0.5. Maximum AC charging power the vehicle's onboard charger can accept — caps the effective charger power.

PV energy available in charging window

The EV Charging from Solar worked example uses PV energy available in charging window = 15 kWh. This value is passed directly into the calculation, with an allowed minimum 0. Forecast/measured solar energy produced during the charging window, available for direct EV charging.

Vehicle consumption

The EV Charging from Solar worked example uses Vehicle consumption = 160 Wh/km. This value is passed directly into the calculation, with an allowed minimum 50. Vehicle's real-world energy consumption, used to translate added energy into driving range.

EV Charging from Solar formulas and result interpretation

Formula 1: relationship used

In the EV Charging from Solar, E_needed = Cap / η. The quantities in this relationship come from the named inputs or from an earlier calculation step shown in the worked example.

Formula 2: relationship used

In the EV Charging from Solar, Time = E_needed / P_solar. The quantities in this relationship come from the named inputs or from an earlier calculation step shown in the worked example.

Charging time

For the displayed EV Charging from Solar worked example, Charging time is 5.41 h. Verify EV battery capacity, Starting SOC, and Target SOC and their units before relying on this output.

Required input energy

For the displayed EV Charging from Solar worked example, Required input energy is 40 kWh. Verify EV battery capacity, Starting SOC, and Target SOC and their units before relying on this output.

Solar-charged share

For the displayed EV Charging from Solar worked example, Solar-charged share is 38 % (15 kWh). Verify EV battery capacity, Starting SOC, and Target SOC and their units before relying on this output.

Grid import needed

For the displayed EV Charging from Solar worked example, Grid import needed is 25 kWh. Verify EV battery capacity, Starting SOC, and Target SOC and their units before relying on this output.

Surplus PV exported

For the displayed EV Charging from Solar worked example, Surplus PV exported is 0 kWh. Verify EV battery capacity, Starting SOC, and Target SOC and their units before relying on this output.

Range added

For the displayed EV Charging from Solar worked example, Range added is 225 km. Verify EV battery capacity, Starting SOC, and Target SOC and their units before relying on this output.

EV Charging from Solar accuracy, checks and limitations

  • EV Charging from Solar units check: confirm EV battery capacity (kWh), Starting SOC (%), Target SOC (%), Charger conversion efficiency (%), Charger power (kW), Vehicle onboard charger limit (kW), PV energy available in charging window (kWh), and Vehicle consumption (Wh/km) before calculating.
  • EV Charging from Solar result check: compare Charging time, Required input energy, Solar-charged share, Grid import needed, Surplus PV exported, and Range added with the substituted formula steps and the displayed rounding precision.
  • EV Charging from Solar: Use this result for preliminary design and cross-checking. Confirm the applicable code edition, manufacturer data, site conditions and qualified-engineer approval before final design or installation.

Understanding the result

Read the main result together with supporting checks, assumptions, limits and intermediate values.

For a manual check, repeat the first equation, confirm the units and change one input at a time.

Common mistakes when using EV Charging from Solar

  • Do not mix units for EV battery capacity (kWh), Starting SOC (%), Target SOC (%). A unit mismatch changes the input magnitude even when the typed number looks reasonable.
  • Do not replace the displayed E_needed = Cap / η relationship with a different convention without also changing the underlying assumptions; compare like-for-like methods when checking the result.
  • Do not treat Charging time = 5.41 h from the worked example as a universal answer. It belongs to the displayed example inputs and must be recalculated for the actual case.

When the EV Charging from Solar is useful

EV Charging from Solar is designed for cases where EV battery capacity, Starting SOC, Target SOC, Charger conversion efficiency are known and you need Charging time, Required input energy, Solar-charged share. The page keeps the live calculator, calculation method and worked example together so the result can be checked instead of treated as a black-box number.

Use the calculator for the scope described by its inputs and notes. The displayed method is E_needed = Cap / η. If the real project or decision needs factors that are not represented here, treat the result as an estimate and add the missing checks separately.

EV battery capacity and Starting SOC: what changes the answer

The worked example uses EV battery capacity = 60 kWh, Starting SOC = 20 %, Target SOC = 80 %, Charger conversion efficiency = 90 %. With those values, Charging time is 5.41 h. Changing an input should be interpreted according to that field's unit, range, option and hint rather than by the number alone.

For this calculator, the main input roles are: EV battery capacity (kWh): Usable capacity of the vehicle's traction battery pack. Starting SOC (%): State of charge at the start of the charging session. Target SOC (%): Desired state of charge at the end of the session — must exceed starting SOC. Charger conversion efficiency (%): AC-DC (or DC fast-charge) conversion efficiency including cabling and onboard charger losses.

How to sanity-check a EV Charging from Solar result

Start by confirming the entered values and units, then compare the substituted working with the displayed formula or calculation steps. Pay particular attention to Charging time, because it is the first worked-example output shown by the live engine.

Finally, compare the result with the assumptions, warnings and related calculators on this page. A nearby calculator can be useful as a cross-check when it measures the same workflow from a different input or output direction.

Next logical calculator

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Useful next check because both tools use EV battery capacity, while EV vs Petrol Emission Calculator answers a different part of the same workflow.

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Standards, source trail and limitations

References show the method used. Check the current local edition, amendments and project specification before a regulated decision.

Design Assumptions

  • • Battery from 0% to 100%.
  • • Steady insolation.

Engineering Tips

  • ◆Charge during 10:00–14:00 for best solar match.
  • ◆V2G-ready cars can time-shift surplus.

Warnings

  • ▲Below 1.4 kW output most EV BMS won't accept a session.

Standards & References

IEC 61851 (EV supply)OCPP 2.0

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