Power – what is happening now
Power describes how fast electrical energy is being used, produced or transferred. A 3 kW load demands 3 kW at that moment.
THE FIRST TWO TOPICS ARE READY
Energy, battery and inverter school
Short, technically reviewed explanations for anyone who wants to understand the energy system before buying, choosing or using it.
THE SCHOOL IS GROWINGTopics 01 and 02 are available. More reviewed lessons will follow.
Energy, battery and inverter school
Choose a topic
Start wherever you want. Published lessons and planned topics are clearly marked.
Topic 01 · The distinction that explains the system
Power is not energy.
kW tells you how fast energy is being transferred now. kWh tells you how much energy has been transferred over time.
RememberkW is the rate. kWh is the quantity.
kWPower – what is happening now
kWhEnergy – accumulated over time
Energy – accumulated over time
Energy is power accumulated over time. A 3 kW load running for 2 hours uses 6 kWh.
The basic relationship
E = P × t
This simple form applies when power is constant. When power varies, its contribution is summed over time.
Common misconception
“A 16 kWh battery can always supply 16 kW.”
No. 16 kWh describes energy, not maximum power. The inverter, battery, BMS, cabling, protection, temperature and settings determine the available kW.
An idealised runtime estimate
16 kWh ÷ 4 kW = 4 hours. Real runtime may be shorter because the usable operating window, losses, auxiliary consumption, temperature and ageing matter.
16 kWh÷4 kW=4 h
▼ Want to go deeper?
For varying power, energy is the area under the power curve. Wh and kWh are the main units used here; 1 Wh = 3,600 J.
E = ∫ P(t) dt
Understanding, not wiring instructions
Battery systems can deliver very high fault currents. Product limits, documentation, risk assessment, protection and regulatory responsibility must be assessed for each installation. Regulated work must be performed by a registered electrical contractor.
Check your understanding
Take a new quiz each time
Six questions are drawn and shuffled from a larger bank. Three have one correct answer and three have several.
Web edition v1.3 · approved
Real systems as teaching material
HF39, BB86, SLS22, KV646 and VB262 show why capacity, power, load profile, production and control must be considered together. They are documented case entries, not universal recipes.
Real systems as teaching material
HF39, BB86, SLS22, KV646 and VB262 show why capacity, power, load profile, production and control must be considered together. They are documented case entries, not universal recipes.
Real systems as teaching material
HF39, BB86, SLS22, KV646 and VB262 show why capacity, power, load profile, production and control must be considered together. They are documented case entries, not universal recipes.
Real systems as teaching material
HF39, BB86, SLS22, KV646 and VB262 show why capacity, power, load profile, production and control must be considered together. They are documented case entries, not universal recipes.
Real systems as teaching material
HF39, BB86, SLS22, KV646 and VB262 show why capacity, power, load profile, production and control must be considered together. They are documented case entries, not universal recipes.
Real systems as teaching material
HF39, BB86, SLS22, KV646 and VB262 show why capacity, power, load profile, production and control must be considered together. They are documented case entries, not universal recipes.
Planned topics
SOC and DOD, cold-weather LiFePO4, hybrid and string inverters, semi-off-grid, ATS interlocking, Local Solar Forecast, work_limit and remote follow-up.
Battery capacity – from label to reality