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Energy, explained with numbers

Long-form guides that go past the brochure: how the technology works, what it really costs, typical ranges with sources, and worked examples you can rerun in our calculators.

32 guides230 minutes of readingLast updated 12 November 2026

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EVs & transport

Are Electric Cars Really Greener? A Life-Cycle Analysis

Battery manufacturing, grid mix, mining and recycling: what life-cycle studies show about EV vs petrol and diesel CO₂, with breakeven distances by country.

7 min read · 9 sections Solar

Are Solar Panels Worth It? Payback, Savings and When They Aren't

A numbers-first guide to whether home solar pays: costs, payback periods, self-consumption, export tariffs, batteries and the cases where it doesn't.

7 min read · 10 sections Heating

Heat Pumps Explained: COP, SCOP and Real-World Costs

How heat pumps work, what COP and SCOP really mean, typical running costs versus gas, sizing rules and when a heat pump pays back. Worked examples included.

8 min read · 9 sections Batteries & storage

Home Battery Storage: How to Size, Choose and Judge the Payback

How home batteries work, how many kWh you really need, LFP vs NMC, round-trip losses, cycle life and when a battery pays back, with worked examples.

8 min read · 7 sections Solar

How Solar Panels Work: From Photon to Plug

How a solar panel turns sunlight into household electricity: the photovoltaic effect, cells, modules, inverters, losses and real-world yields explained.

8 min read · 10 sections

Energy basics

5 guides
  1. Energy Units Cheat Sheet: kWh, MJ, BTU, Therms, toe and More Every energy and power unit in one place: conversion tables for kWh, MJ, BTU, therms, toe, barrels of oil, plus fuel energy contents and worked examples. 6 min
  2. kW vs kWh: The Difference Between Power and Energy kW measures power (a rate), kWh measures energy (an amount). Clear examples for bills, solar panels, batteries and EV chargers, plus common mistakes. 6 min
  3. LCOE Explained: How to Compare the Cost of Electricity from Any Source Levelised cost of electricity explained: the formula, discount rates, capacity factor, worked solar and gas examples, typical ranges and what LCOE leaves out. 7 min
  4. The Global Energy Transition in Numbers: Where the World Stands The energy transition in hard data: electricity mix, solar and wind growth, coal, emissions, primary energy and the gap to climate goals. Latest-year figures. 7 min
  5. What Is Capacity Factor? The Number Behind Every Power Plant Capacity factor explained: the formula, typical values for solar, wind, nuclear, hydro and gas, and how it differs from efficiency, with worked examples. 7 min

Solar

5 guides
  1. Are Solar Panels Worth It? Payback, Savings and When They Aren't A numbers-first guide to whether home solar pays: costs, payback periods, self-consumption, export tariffs, batteries and the cases where it doesn't. 7 min
  2. Best Angle for Solar Panels: Tilt and Direction by Latitude Optimal solar panel tilt and orientation for any latitude, how much you lose on flat or east-west roofs, seasonal angles, trackers and snow. 7 min
  3. How Solar Panels Work: From Photon to Plug How a solar panel turns sunlight into household electricity: the photovoltaic effect, cells, modules, inverters, losses and real-world yields explained. 8 min
  4. Off-Grid Solar: How to Design a System That Survives Winter Design an off-grid solar system step by step: load audit, worst-month sizing, battery autonomy, inverter and charge controller choice, generator backup, costs. 7 min
  5. Solar Panel Efficiency Explained: What the Percentage Really Means What solar panel efficiency measures, typical values by technology, why 22% beats 20% only on small roofs, and how heat and light change real output. 7 min

Wind

3 guides
  1. How Wind Turbines Work: Aerodynamics, Power Curves and the Betz Limit How a wind turbine turns moving air into electricity: lift, the cube law, the Betz limit, power curves, gearboxes vs direct drive, control and capacity factor. 7 min
  2. Offshore Wind Explained: Turbines, Foundations, Costs and Output How offshore wind farms work: turbine sizes, fixed vs floating foundations, capacity factors of 40–55%, cables, costs and the trade-offs against onshore wind. 8 min
  3. Small Wind Turbines for Homes: Do They Work, and Where? An honest guide to home wind turbines: what a 1–20 kW turbine really produces, why rooftop turbines disappoint, siting rules, costs and payback vs solar. 7 min

Batteries & storage

2 guides
  1. Energy Storage Technologies Compared: Batteries, Pumped Hydro and More Lithium-ion, LFP, sodium-ion, flow batteries, pumped hydro, compressed air, thermal and hydrogen storage compared on cost, efficiency, duration and lifetime. 8 min
  2. Home Battery Storage: How to Size, Choose and Judge the Payback How home batteries work, how many kWh you really need, LFP vs NMC, round-trip losses, cycle life and when a battery pays back, with worked examples. 8 min

Grid & markets

4 guides
  1. Carbon Intensity of Electricity: g CO₂/kWh by Country and Source What grid carbon intensity means, how it is calculated, values by country and power source, average vs marginal emissions, and how to use it for your footprint. 7 min
  2. How the Power Grid Works: Generation, Transmission, Balancing How electricity gets from power station to socket: voltage levels, frequency control, reserves, losses, markets and what changes as wind and solar grow. 8 min
  3. Natural Gas and the Energy Transition: Bridge Fuel or Dead End? Natural gas in numbers: emissions vs coal, methane leakage, LNG, the 2022 price shock, gas in power, heat and industry, and how fast demand may fall. 7 min
  4. Why Electricity Prices Spike: Merit Order, Gas and Scarcity Why wholesale power prices jump from €50 to €500/MWh: the merit order, gas setting the price, scarcity, negative prices, and what it means for your bill. 7 min

Home energy

2 guides
  1. Home Insulation Guide: U-Values, Costs and Payback by Measure Which insulation saves most? U-values, heat loss maths, costs per m², payback for loft, wall, floor, windows and airtightness, with worked examples. 7 min
  2. How to Cut Your Electricity Bill: 20 Measures Ranked by Savings A data-driven guide to lowering your electricity bill: where the kWh go, which appliances cost most, tariffs, standby power, LED, solar, with worked numbers. 7 min

Heating

2 guides
  1. Heat Pumps Explained: COP, SCOP and Real-World Costs How heat pumps work, what COP and SCOP really mean, typical running costs versus gas, sizing rules and when a heat pump pays back. Worked examples included. 8 min
  2. Heat Pumps in Cold Climates: Performance Below −15 °C Do heat pumps work in freezing weather? Real COP data at −10 to −25 °C, defrost losses, sizing, backup heat and lessons from Norway, Finland and Canada. 7 min

EVs & transport

2 guides
  1. Are Electric Cars Really Greener? A Life-Cycle Analysis Battery manufacturing, grid mix, mining and recycling: what life-cycle studies show about EV vs petrol and diesel CO₂, with breakeven distances by country. 7 min
  2. Electric Car Charging Guide: Levels, Speeds, Costs and Batteries Everything about charging an EV: AC vs DC, kW vs kWh, real charging times, home vs public costs, charging curves, battery health and smart charging. 8 min

Hydro & marine

1 guide
  1. Hydropower Explained: How It Works, Costs and Environmental Impact Hydropower from first principles: the power formula, turbine types, run-of-river vs reservoir, pumped storage, costs, emissions, drought risk and micro-hydro. 7 min

Climate & carbon

1 guide
  1. Renewable vs Low-Carbon vs Clean Energy: What's the Difference? Renewable, low-carbon, clean, green, zero-emission: what each term really means, lifecycle CO₂ by technology, and why nuclear and biomass divide opinion. 7 min

Policy

1 guide
  1. Coal Phase-Out Around the World: Who Is Quitting, Who Is Building Coal still generates a third of the world's electricity. Which countries are phasing it out, who is still building plants, and what replaces coal in practice. 8 min

Other technologies

4 guides
  1. Bioenergy and Biogas Explained: Biomass, Biomethane and Biofuels How bioenergy works: wood heating, biomass power, anaerobic digestion, biomethane and biofuels. Yields, costs, carbon accounting and the land-use debate. 7 min
  2. Geothermal Energy Explained: Power Plants, Heat and Enhanced Systems How geothermal works, from Icelandic power plants to enhanced geothermal systems and ground-source heat pumps: resources, costs, emissions and outlook. 7 min
  3. Green Hydrogen Explained: Costs, Efficiency and Where It Makes Sense How green hydrogen is made, electrolyser types, efficiency losses, the real cost per kg, and which uses make sense: steel, ammonia, shipping, not home heating. 7 min
  4. Nuclear Power: Pros and Cons, Costs, Safety and Waste A balanced, data-driven look at nuclear power: emissions, safety record, waste, construction costs and delays, SMRs, and its role alongside renewables. 7 min
Prefer to run the numbers yourself? Every guide links to the matching tool. Browse all calculators, compare country energy profiles, or click anywhere on the Energy Explorer map for local sun and wind data.