Photovoltaic systems the number has increased in Finland in recent years.
Solar Technology Association Executive Director Christer Nyman also works as a consultant in the field. According to him, the popularity is primarily explained by the price of photovoltaic systems, the development of which has favored the consumer.
“The price has dropped or remained constant enough to be able to calculate reasonable payback periods. Another reason is that green electricity certainly influences people’s choices, ”Nyman says.
The EU waived the path tariff on panels from China in 2018, when the goals of renewable energy production did not want to be achieved without cheap Chinese production. Now Nyman thinks price developments are more difficult to predict due to the koruna, but a sharp decline in previous years is not expected, he said.
Not the number of panels, but the power
However, Nyman points out a general misconception about the cost of solar panels: the price does not depend on the number of units of solar panels, but on their efficiency.
For example, panel systems connected to the electricity grid of detached houses are, according to him, about 1000–2000 euros per kilowatt. The most common power of the panels is between 200 and 300 watts. Five kilowatt panels would need five kilowatts, while three 300-watt panels would already be closer to the same power.
According to Nyman, the price difference between these options depends on the manufacturer. Finland solar panels are manufactured in Salo, but more than half of the solar panels are still imported from China, according to Nyman. Production takes place in Estonia and elsewhere in Europe, for example, where companies often assemble cells made in China into complete panels.
“In China, the price range and quality of the panels vary,” Nyman says.
One essential criterion is quality
One of the most important criteria for determining quality is the energy guarantee of the panel. According to Nyman, a good panel should generate electricity for at least 20 years. After more than 20 years, another 80 percent of the power should be released.
“Other manufacturers don’t mention the energy guarantee at all, but the panels come with a lot of other numerical information. It can confuse a private buyer. It is therefore recommended that you do not trade immediately if you do not understand enough. It’s worth asking for quotes from many places. ”
This way you can save on your electricity bill
So what is the payback period for solar panels? It depends on how much the system has invested in and how much electricity the property consumes.
“It is not worth looking at electricity only on an annual basis, but on a monthly and hourly basis. If you buy a system that is too big, which is oversized in relation to the hourly consumption of the house, a lot of electricity is wasted in the grid, ”says Nyman.
For example, the electric heating of a medium-sized detached house can be 20,000-40,000 kilowatt hours per year. If a one-kilowatt photovoltaic system is installed in the house, it will produce about 800 kilowatt-hours a year in Finland, according to Nyman. A five-kilowatt system would thus produce 4,000 kilowatt-hours per year, and so on.
“However, ten kilowatts is usually too much, especially when there is no heating in the summer. Peak power is often a couple to three kilowatts per hour, ”Nyman explains.
Some electricity companies pay for the surplus produced in the electricity grid, but the price depends on the value and amount of electricity currently purchased. In oversized systems, the payback period is more likely to be extended, Nyman sums up.
“If the system is optimized and all the electricity it produces can be utilized in the consumption of the house, the savings will come. The repayment period can be from five to ten years. However, it makes sense, because good panels should last 20 years. ”
Cold is the best time for panels
The amount of sunlight naturally affects the power generation of the panels. It is a good idea to install the solar panel in an open area that is not shaded by buildings or trees.
“It may be the cheapest to install on the roof and the systems are good because they have ready-made racks on which to place the panels. However, if the roof is old or needs to be replaced in the future, the entire system will need to be dismantled in the worst case. On the roof, it’s also harder to visit them yourself. If there is space, you can also do ground installations in the yard of a detached house, ”says Nyman.
In winter, the power is lower due to the amount of light. According to Nyman, the panels will start producing properly again in February-March. Contrary to popular belief, however, winter time may be more favorable for electricity generation. For example, a 300-watt solar panel produces as much power as its rated power under ideal conditions, i.e., when the temperature in the panel itself is 25 degrees.
“The power of the panels drops too hot. It is possible that the panel will even exceed its peak performance in the spring in the cold. Especially in cold and sunny conditions, the power is at its best. ”