Before installing photovoltaic panels on the roof, it is essential to correctly size the system – so that it can provide – an adequate yield for your energy needs. In this study, we will see in detail How Much Electricity Do Solar Panels Generate, analyzing the factors that influence the yield and providing some useful tips to maximize performance.
What does the production of a photovoltaic system depend on?
A photovoltaic system can exploit sunlight to produce electricity, thanks to the photovoltaic cells that make up the modules. However, the performance of photovoltaic panels is determined by various factors:
- Type of modules (power, materials, quality, technologies);
- Inclination and orientation of the panels;
- Operating temperature of the system;
- Solar radiation;
- Weather and environmental conditions.
These possible variables make us understand that photovoltaic modules are not all the same, but based on:
- Quality;
- To power;
- To materials and integrated technologies.
Offer a certain basic efficiency. For example, while polycrystalline silicon photovoltaic panels have an efficiency of around 16-18%, monocrystalline silicon panels have an efficiency of up to 19-21%.
The same applies to the orientation and inclination of photovoltaic panels, two fundamental aspects studied by technicians to guarantee the best possible performance through an optimal configuration of the modules.
Even the ambient temperature affects the production of electrical energy of photovoltaic panels, which ensure maximum efficiency at a temperature of 25°C.
Another factor that affects the system’s performance is solar radiation, which is generally higher in the Southern than in the North.
Finally, environmental and meteorological conditions should not be underestimated, considering that the production of photovoltaic panels in winter and on bad weather days is reduced compared to summer and on good weather days.
How many kW does a photovoltaic panel produce?
As we have seen, the production of electrical energy of a photovoltaic panel is quite variable; in fact, it is not constant throughout the year and the day. For this reason, the manufacturers of photovoltaic modules indicate an estimate of performance, calculated in optimal conditions of temperature and solar radiation.
For example, calculating how much a 100 W photovoltaic panel produces, we get an average of about 100-120 kWh of electrical energy. However, most of the modules sold today have a power of 300-400 W, with a yield of around 500-650 kWh.
How many panels are needed for a 4 kW production?
The number of solar panels needed to produce 4 kW depends on the power of each panel. Power is measured in kilowatts-peak (kWp) and to determine the number of panels needed, you can use the following formula:
Number of panels = Desired power (kW) ∶ Power of each panel (kWp)
For example, if the solar panels you are considering have a power of 300 pico-watts (0.3 kWp) each, the formula would be:
Number of panels = 4 kW ∶ 0.3 kWp/panel ≈ 13.33 panels
Since the number of panels must be whole, you would need at least 14 panels of 300 watt-peak each to get a total production of 4 kW.
What is the yield per m²?
The yield of a photovoltaic system, expressed in kWp/m², represents the amount of power that can be generated for each square meter of area occupied by the photovoltaic panels. For example, if you have an 8 kWp system that occupies 40 m², the yield will be 0.2 kWp/m². This indicates that on average the system produces 0.2 kWp of power for each square meter of solar panels.
How much does a photovoltaic system produce in a year?
To determine how much a photovoltaic system produces, simply add the performance of each panel, obtaining an estimate of the overall performance of the system. Let’s look at some examples:
- A 3 kW photovoltaic system has a yield of around 11 kWh of electrical energy per day, while in a year it is possible to expect production of around 500 kWh ;
- A 4 kW one has a daily yield of around 14.7 kWh, with an annual yield of around 300 kWh ;
- With a 6 kW system it is possible to obtain an average daily yield of around 22 kWh, reaching around 000 kWh of electrical energy in a year;
- If we consider an 8 kW photovoltaic system, we can use a rough estimate of 1,200 kWh produced per year for each kWp (kilowatt-pico) installed in areas with good solar conditions. So, for an 8 kW system, the estimated annual production would be around 600 kWh.
A useful tool for estimating the electricity production of a photovoltaic system in the Philippines is the solar map, which allows you to calculate in a simple and reliable way the performance of a system in the various areas of our country based on the different solar radiation.
Using this tool, considering the average-standard annual solar energy production for a particular geographic area, it is possible to obtain a customized estimate of the expected production of the plant, both for grid-connected and off-grid systems. For example, in an area with good solar conditions, a 100 kW photovoltaic plant could produce between 120,000 and 150,000 kWh per year.
How to optimize the performance of your photovoltaic system
To increase the yield of a photovoltaic system, it is possible to adopt some useful measures:
- Install a green plant cover on the roof if possible, to avoid an excessive increase in operating temperature which reduces the performance of the photovoltaic panels;
- Use photovoltaic optimizers in the presence of partial shading to improve the performance of individual modules;
- Keep the panels always clean and in good condition;
- Rely on professionals to ensure the correct installation of photovoltaic modules;
- Choose high-efficiency panels such as the new generation monocrystalline modules.
Solarlab guarantees high performance in terms of energy efficiency. Furthermore, it is possible to take advantage of the support of expert professionals, able to identify any critical issues and design a correctly sized and configured system to maximize performance, with dedicated assistance in every phase, from the initial inspection to the management of the procedures for connection to the electricity grid.