As a guideline value, a single-family home can manage with around 15 to 25 modules – which corresponds to about 6 to 10 kWp. The exact number depends less on current electricity consumption than on the usable roof area and what else is added: a heat pump or an e-car noticeably shift the calculation upwards. (As of: July 2026)
Key points in brief
- For a typical single-family home, around 15 to 25 modules are a good guideline value, i.e. about 6 to 10 kWp.
- A modern module today produces approximately 400 to 450 watts and measures almost two square metres.
- It is not current consumption that decides, but the usable roof area and future demand.
- Heat pump and e-car significantly increase electricity demand – and accordingly justify more modules.
- Only the planning for your roof delivers the exact number; sonnendach.ch provides an initial indication.
How many modules does a single-family home need on average?
For an average single-family home, the guideline value is around 15 to 25 modules. This is deliberately a range, because two houses with the same footprint can have very different needs. The following table provides an initial orientation.
| Situation | Guideline value modules | approx. output |
|---|---|---|
| Small household, no heat pump, no e-car | around 12–16 | approx. 5–7 kWp |
| Average single-family home | around 16–22 | approx. 7–9 kWp |
| Household with heat pump and/or e-car | around 22–30 and more | approx. 9–12 kWp |
| Target full roof coverage | as many as the roof can carry | maximum possible |
Guideline values, as of: July 2026. Individual planning for your roof is decisive; a quote provides binding values.
The figures show a pattern: the jump is caused less by the number of people in the household than by large, controllable consumers. An economical two-person household and a family with a heat pump and e-car are far apart in terms of the sensible number of modules.
Is it better to calculate by electricity consumption or by roof area?
The most common misconception is: "I consume X kilowatt hours, so I need exactly enough modules for the system to deliver X." This calculation falls short. On the one hand, a system produces unevenly over the year and over the day – the annual total rarely matches the demand at the right moment. On the other hand, consumption changes: anyone who calculates without a heat pump and e-car today may be dimensioning for a house that will no longer exist in five years.
In practice, two variables reliably lead to the goal: the usable roof area and the foreseeable future demand. The roof sets the upper limit, the demand dictates whether it should be exhausted. The article Overview of feed-in tariffs shows how strongly your grid operator's tariff plays into this question; the article Optimise self-consumption describes which levers increase self-consumption.
How much output and area does a single module have?
A modern module today yields around 400 to 450 watt-peak and measures almost two square metres. From these two values, the number of modules can be roughly derived. For the desired output, divide the kWp figure by the module output: an 8 kWp system corresponds to about 19 modules for 420 watt modules. For the area, one calculates with approximately 5 to 7 square metres of roof area per kWp.
What watt-peak, kilowatt-peak and kilowatt hour exactly mean and why the nominal output does not correspond to the everyday yield is explained in the article Watt-peak simply explained. Anyone who wants to go through the complete calculation with roof area, consumption and yield can find it under Calculate PV system size.
Cover the whole roof or only current demand?
We take a clear stance here: in most cases it is worthwhile to cover the suitable roof generously, rather than planning tightly around current consumption. Three points speak in favour of this.
Firstly, the cost structure. Scaffolding, travel, electrical work and the notification procedure are incurred largely independently of the system size. If these fixed costs are distributed over more kilowatts, the price per kWp falls – the derivation for this is in the article What does a solar system cost?. Secondly, future demand: a heat pump and e-car will sooner or later come to many houses, and then every additional module is welcome. Thirdly, the fed-in surplus also generates a yield, even if it is lower than the value of the self-consumption.
We are only more cautious in one constellation: low feed-in tariff, no foreseeable extra consumption and a tight budget. Then the system tailored to personal requirements can be the better choice. The article Self-consumption or feed-in? delves deeper into this trade-off – whole roof or half.
How do heat pump and e-car change the number of modules?
Both are large consumers and shift the sensible number of modules upwards. As a guideline value, a heat pump increases the annual electricity demand of a single-family home by several thousand kilowatt hours; an e-car by another four-digit amount, depending on mileage. Thought of in modules, this quickly means a handful more.
The practical advice: anyone who considers a purchase possible in the next few years is better off planning the modules in right away. A later expansion in two stages is technically feasible, but rarely economical – scaffolding and notification procedure are then required a second time. The articles Combine heat pump with photovoltaics and Charge e-car with solar electricity show how the building blocks interact.
How do I find the exact number for my roof?
The official portal sonnendach.ch provides an initial indication: enter the address and you will see the rough suitability and the area potential of your roof. How you interpret the data correctly is explained in the article Using sonnendach.ch correctly. The value is an estimate, not a substitute for on-site planning.
The binding number is only generated when someone actually surveys the roof: area, orientation, shading by chimneys or neighbouring trees, the position of windows and skylights. The number of modules that fits your house emerges from these details and your consumption profile.
In consultations, we see two recurring patterns. One: planned tightly for current consumption – and a year later the heat pump arrives, but the roof is already full with a system that is too small. The other: a large, well-sunned roof that is cautiously only half covered, while the free area remains unused for decades. Both can be avoided with an honest look at the next ten years – the number of modules is a planning decision, not a gut decision.
Frequently asked questions
How many modules fit on an average single-family home roof?
That depends on the area and its shape. There is often space for 15 to 30 modules on a easily usable half of the roof. How much your roof yields is shown by a first look at sonnendach.ch, it becomes binding with the roof survey.
How many solar modules do I need for a heat pump?
As a guideline value, a heat pump justifies some additional modules, because it increases the annual electricity demand by several thousand kilowatt hours. The exact number depends on the building, the heating load and your consumption profile.
Can I add more modules later?
Technically yes, economically rarely sensible. Scaffolding, travel and notification procedure are incurred again for a second expansion. Anyone who considers an expansion possible is better off planning the modules generously from the start.
How many modules do I need for an e-car?
Depending on mileage, an e-car increases the demand by a four-digit kilowatt-hour amount per year. As a guideline value, this corresponds to a handful of additional modules – ideally, charging takes place when the sun is shining.
Are more modules always better?
Not necessarily. Limits are set by the roof area, the budget and the feed-in tariff of your grid operator. Because the additional modules are comparatively cheap, however, generous coverage is more often worthwhile than many think.
How much electricity do around 20 modules deliver?
About 20 modules yield roughly 8 to 9 kWp. In the Zurich region, as a guideline value, this corresponds to an annual production of approximately 8,000 to 9,500 kWh – depending on orientation and shading.
Free initial consultation
How many modules fit on your roof?
We survey your roof, take consumption, heat pump and e-car plans into account and tell you the sensible number of modules – free of charge and without obligation.
Prefer to talk? +41 78 830 83 35
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Swissolar-certified specialist company · ESTI installation authorisation (Art. 14 NIV) · in Zurich since 2017 · over 150 systems completed · a personal answer from the specialist company, no call centre
Sources: Swiss Federal Office of Energy SFOE, EnergieSchweiz, Swissolar, sonnendach.ch (SFOE / swisstopo).
Last updated: 9 July 2026 · Author: ecoEn editorial team
