What Size UPS Do I Need for My Computer?
The UPS size you need depends on your computer’s total wattage plus all connected peripherals. A basic desktop with one monitor needs 600 to…
Solar Basics
Free solar tools
Size your solar system in five minutes.
Free calculators for panels, batteries, inverters and cost — no sales calls, no sign-up.
The toolkit
Solar calculators that actually finish the job
Each tool is free, instant, and works in your browser. More arrive regularly.
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AC/DC Adapter & Converter Calculator
Find the exact adapter, inverter, or converter for any device.
Open →📋Appliance Wattage Database
Look up the wattage of 140+ household appliances.
Open →🔋Battery Backup Calculator — How Long Will Your Battery Last?
Calculate how long any battery lasts under your load with runtime by appliance.
Open →🧰Battery Charge & Discharge Calculator — Free Tool
Charge rate, runtime, solar panel count, and inverter sizing for any battery.
Open →⚙️Electrical Unit Converter
Convert between volts, amps, watts, kWh, and other electrical units.
Open →💡Electricity Bill Calculator
Estimate your monthly electricity bill from your appliances.
Open →🧰EV Charging Cost Calculator
Free interactive solar tool.
Open →🧰Generator Sizing Calculator
Free interactive solar tool.
Open →🧰Inverter Size Calculator
Size your inverter with surge capacity for motor startup — enter appliances, get the kVA rating.
Open →🔁kVA to Watts Converter — Instant Calculation + Power Factor Table
Convert kVA to watts and watts to kVA at any power factor.
Open →🔌Load Shedding Battery Planner
Plan your battery backup for scheduled power outages.
Open →🧰Net Metering Calculator
Free interactive solar tool.
Open →📐Panel Output Calculator
See how much energy your solar panels produce per day, month, and year.
Open →🧰Solar Installation Cost Calculator
Estimate your total installed cost with incentives and cost per watt.
Open →🧰Solar Panel Angle Calculator
Find the optimal tilt angle for your solar panels by latitude with seasonal adjustments.
Open →📉Solar Panel Degradation Calculator
Model how panel output declines over 25 years.
Open →🧰Solar Panel Wire Size Calculator
Find the correct AWG wire gauge for every cable run in your solar panel system.
Open →🧰Solar Roof Space Calculator
See how many panels fit on your roof and the total system kW.
Open →💰Solar Savings Calculator
See your payback period and 25-year savings from solar panels.
Open →☀️Solar System Calculator — Size Panels, Battery & Inverter (Free)
Size your complete solar system — panels, battery, inverter, and controller from your appliance list.
Open →⛽Solar vs Generator Calculator
Compare the 25-year cost of solar versus a fuel generator.
Open →🧰Tools
Free interactive solar tool.
Open →🧰UPS Sizing Calculator
Free interactive solar tool.
Open →🧰Voltage Drop Calculator
Calculate voltage drop across any wire run — see drop percentage, power loss, and NEC compliance.
Open →🔧Wire Gauge Calculator — AWG Size for Any Current & Length
Find the correct cable AWG for any current, length, and voltage drop limit.
Open → 🧰Browse all tools
See the full and growing library of solar and electrical calculators in one place.
View library →🎯
Built by the numbers
Real engineering: depth-of-discharge, surge loads, round-trip losses and MPPT sizing — not rough guesses.
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No sales calls
Independent and free. We size your system so you walk into any quote already knowing the answer.
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Works anywhere
Region sun-hours, editable local prices and any currency — accurate whether you're in Texas or Karachi.
From the blog
Solar guides & comparisons
Solar Basics
UPS vs Inverter: What Is the Difference?
A UPS (uninterruptible power supply) and an inverter both convert battery power to AC electricity, but they serve fundamentally different purposes. A UPS provides…
UPS & Backup
How Long Will a UPS Last? (Runtime by Load)
UPS runtime depends on three factors: the UPS battery capacity (measured in VA or Wh), the connected load in watts, and the battery’s age…
Solar Panels
How Many Solar Panels to Charge an Electric Vehicle?
The average American drives 30 to 40 miles per day, which requires 8 to 13 kWh of electricity to recharge. At 5 peak sun…
EV Charging
Cost to Charge a Tesla at Home vs Supercharger (2026)
Charging a Tesla at home costs 7 to 12 dollars for a full charge at the US average electricity rate of $0.16/kWh. At a…
Cost & Savings
What Is Net Metering? How It Works (Simple Guide)
Net metering is a billing arrangement where your utility credits you for excess solar electricity you export to the grid. When your solar panels…