In the solar PV market, kW have often become the main “sales argument”. We hear proposals for large systems, general figures and one-size-fits-all solutions, without always taking into account the actual needs of each home or business. The result is systems that, despite having a high capacity, do not deliver the expected benefits.
Why kW cause confusion
kW indicate the rated capacity of a photovoltaic system. But they don’t show:
- how much energy we will use,
- how much our bill will be reduced,
- or whether the system is properly suited to our lifestyle.
As a result, many systems are “sold” based on kW, not on actual results.
A larger system doesn’t always mean greater benefits
Today, with Net Billing:
- surplus energy is sold at market prices,
- these prices fluctuate,
- and are often lower than the price we pay for electricity.
This means that an oversized system:
- doesn’t necessarily increase savings,
- may have higher installation costs,
- and may deliver a lower return per euro invested.
The goal isn’t to produce as much energy as possible, but to make good use of the energy we produce.
What really determines how many kW we need
The right capacity for a photovoltaic system isn’t determined by general rules, but by analyzing specific factors, such as:
- annual electricity consumption,
- when during the day energy is consumed,
- whether we use a heat pump or an electric vehicle,
- and whether or not we have a storage battery.
Two homes with the same floor area may need completely different systems.
The real “size” is self-consumption
Today, the most important measure isn’t kW, but the self-consumption rate.
The more energy we consume ourselves:
The more energy we consume ourselves:
- the greater the financial benefit,
- the less dependent we are on the grid,
- and the more efficient the investment.
A smaller, well-designed system can perform better than a larger one that isn’t fully utilized.
Common mistakes when determining kW
In practice, we often see:
- systems designed without an analysis of consumption,
- choices based on “what everyone else is installing”,
- or proposals focused solely on maximizing capacity.
These choices lead to disappointment and lower-than-expected performance.
How to choose the right capacity
To choose the right kW:
- we always start with consumption data,
- we examine how and when we use energy,
- we design for self-consumption rather than overproduction,
- and adapt the system to our future needs.
A proper assessment is what determines the system’s success.
In solar PV, kW alone don’t tell the whole story.
The real benefit isn’t in the size of the system, but in how well it matches our needs.
When we design based on consumption, self-consumption and our lifestyle, we avoid oversizing and achieve meaningful savings over the long term.
The real benefit isn’t in the size of the system, but in how well it matches our needs.
When we design based on consumption, self-consumption and our lifestyle, we avoid oversizing and achieve meaningful savings over the long term.
