Nine calculators for the DC side of energy
Every tool runs in your browser, updates as you type and shows the assumptions it uses. No sign-up. When you want real prices, one click carries your result into a free quote request.
DC fast-charge time
Models a typical lithium-ion charging curve: full power to ~50%, tapering after, steep above 80%.
0%50%80%100%
- Energy into battery
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- Energy from charger
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- Average power
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- Range added
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Charging cost vs gas
Includes charging losses: ~12% at home (AC), ~7% on DC fast chargers.
US average residential electricity was about 17.3¢/kWh in 2025 (EIA). Use your own bill's rate for accuracy.
Bar = EV cost as a share of the gas cost.
- Same miles on gas
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- Yearly savings
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- Cost per mile
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- 100% home charging
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- 100% DC fast
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Road-trip charging stops
Estimates stops and time on chargers for a highway trip. Cut efficiency by 20–30% for winter driving.
Bar = charging time as a share of total trip time.
- Time charging (incl. 6 min/stop)
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- Time driving
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- Total trip
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- Energy needed
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- Range per leg
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Solar system sizer
Sizes the DC array that offsets your usage. Production uses peak sun hours × array kW × (1 − losses).
Bar = share of annual use covered.
- Panels
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- Roof area (approx.)
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- Target energy
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- Annual production
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- Installed cost
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Solar payback & 25-year savings
Year-by-year model with panel degradation and electricity-price escalation. Enter only incentives that actually apply where you live.
Lower this if exports earn less than retail.
Bar = payback as a share of a 25-year life.
- Net cost
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- Year-1 savings
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- 25-year net gain
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- 25-year ROI
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- Lifetime cost of power
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Battery bank sizer
For off-grid cabins, RVs, vans, boats and backup systems.
Bar = battery current vs a 300 A practical ceiling.
- Capacity
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- Usable energy needed
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- Equivalent
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- Peak battery current
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Power-station runtime
How long a portable power station or battery runs your devices. Tap items to add their typical watts.
Bar = load vs inverter rating.
- Usable energy
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- In days
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- Solar recharge (75% real-world)
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DC wire gauge & voltage drop
Picks the smallest AWG that meets both your voltage-drop limit and a 125% continuous-current ampacity check.
1 m ≈ 3.28 ft. Round trip is calculated for you.
Bar = actual drop vs your limit.
- Metric equivalent
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- Actual voltage drop
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- Heat lost in cable
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- Suggested fuse
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- Required area
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Ohm's law & DC power
Enter any two of voltage, current, resistance or power. V = I × R and P = V × I.
Enter any two values.
- Voltage
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- Current
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- Resistance
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- Power
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- Energy over run time
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How these calculators work
Transparent assumptions
Every default comes from public sources (US DOE AFDC, fueleconomy.gov, NREL PVWatts, EIA, Battery University). Change any input to match your situation.
Estimates, not sign-off
Real charging curves vary by car and temperature; real solar output varies by shading and tilt. Use results for planning, then confirm with a qualified installer.
Private by design
All maths runs in your browser. Nothing you type into a calculator is sent anywhere unless you choose to request a quote.