Technology
Four parts, one rule of arithmetic: power is kilowatts now, energy is kilowatt-hours over time.
Fictional company. Every figure on this site is an illustrative example.
The four parts
- Panels
- Panels turn light into direct current. A panel rated 400 W makes up to 400 W in strong, direct light, and less in most hours. Heat lowers output slightly.
- Inverter
- The inverter turns direct current into the alternating current your home uses and manages the connection to the grid.
- Battery
- A battery stores some of the midday surplus. Only part of its nameplate is usable, and some energy is lost on each cycle.
- Monitoring
- An app shows the day as a chart, so you can compare the real day with the illustrative one on this site.
The arithmetic of a day
- A 5 kWp system in clear midday light might make about 4 kW. That is power.
- Over one hour at that rate it makes 4 kWh. That is energy.
- A home using 0.55 kW at that moment has 3.45 kW spare. A battery can take some; the rest goes to the grid.
What changes the result
- Shade
- A chimney or tree can cut output for part of the day. Panels are wired so shade on one does not always stop the rest, but it matters.
- Orientation and tilt
- Roofs facing the sun directly make more. East and west roofs make a flatter, longer day.
- Season
- Summer days are long and winter days are short. The chart here shows an illustrative summer day.
- Your habits
- Running the washing machine at noon raises self-use. Nothing else costs less.
Safety and standards
Any real installation must follow local electrical rules and be done by qualified installers. This concept page makes no claim of certification or approval.