Electricity & Energy guides
10 guides — practical answers with the math shown, each paired with a free calculator.
Electricity & Energy
What Size Solar System Do I Need to Go Off Grid?
7 panels cover a 10 kWh day with 0.08 kWh to spare. Refilling the battery on that surplus takes 125 days.
August 15, 2026 · 10 min read
Electricity & Energy
How Long Will a Battery Run My House? The Two Tests It Has to Pass
A 100 Ah battery is 1,200 Wh, 600 Wh of it usable — and none of that says whether your fridge will start.
August 14, 2026 · 9 min read
Electricity & Energy
What Is a Demand Charge? Load Factor and Your Real Rate per kWh
Two businesses on one tariff can pay 22.27 cents and 14.57 cents a kilowatt-hour, decided by nothing but how evenly they drew power.
August 14, 2026 · 9 min read
Electricity & Energy
What Is Power Factor? The Current Your Watts Do Not Show
Watts describe the result. Volt-amps describe the burden — and conductor heating follows the square of the difference.
August 14, 2026 · 9 min read
Electricity & Energy
What Size Wire Do I Need? Voltage Drop Over a Long Run
The current goes out and comes back, so a 100 ft run is 200 ft of copper — and moving to 240 V helps twice over.
August 13, 2026 · 9 min read
Electricity & Energy
How Many Solar Panels Do I Need? Sizing From Your Real Usage
Daily usage divided by what one kilowatt makes in a day, why sun hours dominate the count, and the wattage trade that saves a tight roof.
July 23, 2026 · 13 min read
Electricity & Energy
How Much Does Heating Cost? By Fuel, Per Month, With Math
The watts-times-hours formula, the $63 default month, why every 1,500 W heater costs the same to run, and where gas and heat pumps land.
July 23, 2026 · 13 min read
Electricity & Energy
How Much Does It Cost to Charge an EV? Home vs Public, Per Mile
The three-line formula, the losses you pay for but never keep, and why home charging beats public by two to four times.
July 23, 2026 · 13 min read
Electricity & Energy
What Size Generator Do I Need? Wattage by Scenario
Running watts plus one surge, times 1.2. The honest tally that gets it right, and the mistake that stalls a generator the moment the compressor kicks in.
July 23, 2026 · 13 min read
Electricity & Energy
How Much Does Electricity Cost? Reading Your Bill in kWh
The kWh formula, the rate your bill actually charges, and what a heater, an always-on device, and standby power really cost.
July 20, 2026 · 6 min read