Record demand
Annual consumption makes clear the relevant energy amount.
Guide
Understand solar system size: what size fits your household?
A useful PV system size follows the household, not a generic roof maximum. Consumption, roof area, yield, self-consumption and battery size must fit together before the investment makes sense.
Quick answer
What solar size really fits?
Focus on which PV system size fits the household and consumption profile. In practice, size the system by consumption and roof potential, not by maximum area alone.
Example
Example: Size the battery from the daily profile
Start by clarifying which PV system size fits the household and consumption profile. Then the comparison clarifies the effect of yearly consumption, roof area, yield, self-consumption and battery and the boundary set by shading, grid connection, investment budget and future demand.
Decision focuswhich PV system size fits the household and consumption profile
Main leveryearly consumption, roof area, yield, self-consumption and battery
Separate checkshading, grid connection, investment budget and future demand
Next stepsize the system by consumption and roof potential, not by maximum area alone
How to read the resultDecision focus: which PV system size fits the household and consumption profile. Separate check: shading, grid connection, investment budget and future demand.
Read the result together with yearly consumption, roof area, yield, self-consumption and battery. Shading, grid connection, investment budget and future demand limit how directly you can act on it.
Decision view
Size the battery from the daily profile
The overview separates result, lever and boundary: which PV system size fits the household and consumption profile; yearly consumption, roof area, yield, self-consumption and battery; shading, grid connection, investment budget and future demand. The overview shows the statement first, then the influence and then the limit.
What the visual shows
The values explain the most important parts of the visual.
Resultwhich PV system size fits the household and consumption profile
Main leveryearly consumption, roof area, yield, self-consumption and battery
Separate checkshading, grid connection, investment budget and future demand
The practical benefit becomes clear only when yearly consumption, roof area, yield, self-consumption and battery are realistic and shading, grid connection, investment budget and future demand are checked separately.
Load profile, weather, seasonal generation and storage losses can change the suitable battery size. Shading, grid connection, investment budget and future demand can change the real-world result and should be reviewed separately before binding decisions.
How it is calculated · Mathematical background
How it is calculated
The formula explains the number. The practical statement also depends on shading, grid connection, investment budget and future demand.
Review roof potential
Area, orientation and shading limit possible PV size.
Estimate annual yield
kWp and specific yield provide expected generation.
Value self-use
The better power is used, the more valuable the system becomes.
Size battery sensibly
The battery should shift surplus without being constantly empty or full.
Review marginal value
Extra size pays off only if additional yield has meaningful value.
The result stays robust when yearly consumption, roof area, yield, self-consumption and battery are realistic and shading, grid connection, investment budget and future demand are not overlooked.
Detailed calculation explanation
PV size is usually stated in kWp. A specific yield converts it into an estimated annual generation. Simplified: annual yield = PV size in kWp × specific yield per kWp. The decision then depends on which share is used directly, stored or fed into the grid.
If-then rules
If-then rules for the decision
When usage or prices can change
The main uncertainty is yearly consumption, roof area, yield, self-consumption and battery. Show it first as a normal case and then as a cautious counter-case.
When choosing technology or tariffs
If shading, grid connection, investment budget and future demand are unclear, read the result as orientation rather than closure.
When planning the next step
Before a binding decision, result, lever and boundary need to be read in the same scenario.
Step by step
How to interpret this topic
Read demand and generation
The decision starts with: which PV system size fits the household and consumption profile. Only the link to yearly consumption, roof area, yield, self-consumption and battery and shading, grid connection, investment budget and future demand makes it robust.
Find the strongest energy lever
The range depends mostly on yearly consumption, roof area, yield, self-consumption and battery. A robust case uses assumptions that remain defensible.
Keep model limits realistic
The calculator can name shading, grid connection, investment budget and future demand, but it cannot settle them. They remain part of the next review.
Plan the next energy step
Before deciding, check whether yearly consumption, roof area, yield, self-consumption and battery still hold under the limits from shading, grid connection, investment budget and future demand.
Checklist
Quick decision check
- Define the starting question: which PV system size fits the household and consumption profile.
- Vary the main lever within the same scenario: yearly consumption, roof area, yield, self-consumption and battery.
- Keep the boundary separate: shading, grid connection, investment budget and future demand.
- Compare base case and cautious case only with the same reference value: which PV system size fits the household and consumption profile.
- Turn the result into action only when yearly consumption, roof area, yield, self-consumption and battery and shading, grid connection, investment budget and future demand remain plausible together.
Common mistakes
Common decision mistakes
solar system size: reading the result without context
Without a benchmark, which PV system size fits the household and consumption profile cannot yet lead to a reliable next step.
solar system size: setting the main lever too optimistically
Planning yearly consumption, roof area, yield, self-consumption and battery too tightly can understate risk, reserve needs and the next step.
solar system size: overlooking the model boundary
As long as shading, grid connection, investment budget and future demand remain open, the result is guidance rather than a final decision.
FAQ
Frequently asked questions
Should I simply fill the whole roof?
The counter-case shows whether the result can become a stable next step.
Is PV size the same as battery size?
The range between normal case and cautious assumption usually matters more than the single end value.
What decision should I make afterwards?
The calculation creates transparency, but shading, grid connection, investment budget and future demand also decide whether the step really fits.