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There are no stupid questions: 6 things you've always wanted to know about solar panels
Renewable energy

25.08.2020

Do you want to save nature, save on electricity costs and increase the value of your real estate? If the answer is yes, you might want to consider installing solar panels.

Although solar energy is gaining more and more popularity both in Estonia and elsewhere in the world, long-term investments raise many questions for people. It's a good idea to make things clear before installing the panels. Advice is given by Ott Antsmaa, Head of Distributed Energy Services at Eesti Energia.


Will solar panels really pay off even if the price of electricity falls over time?

When calculating profitability, the principle is that the financial gain arises from the electricity not purchased from the network and the sale of the leftover electricity. The financial gain obtained must be compared with the investment and running costs of the solar power plant, i.e. the cost price of the solar park.

As network fees and state taxes apply to electricity purchased from the network, it is always more profitable to consume as much self-produced electricity as possible. With sufficient self-consumption, it is certainly possible that a solar power plant will pay for itself even if the price of electricity falls.

According to current long-term expert forecasts, the price of electricity is on the rise, and the more expensive the price of electricity in the network, the faster the solar power plant will pay for itself.

In general, a well-designed plant will pay off in ten years. The construction of a solar park is an investment, the profitability of which must be accurately assessed in advance. If the plant is planned incompetently and sloppily, its payback period can be significantly longer.

What happens if I order the panels from Aliexpress and put them on the roof myself?

A solar power plant is an electrical installation, the installation of which must be left to professionals who ensure that the electrical connections are correct and safe, and that correct fasteners are used. A professional also gives a warranty for the work done.

For devices ordered from an unknown online vendor, there is always a risk that the advertised product will not be the one actually shipped, and any warranty issues may be difficult to resolve.

In addition to solar panels, the inverter is an important component of a solar power plant, and it must be approved by the network operator and have certificates meeting the European standards.

Buying cheap equipment yourself may seem like an attractive alternative, but given that the investment in a solar power plant is very long-term, later problems or system failures can have a negative effect on the profitability of the plant.

How easy is it to modernize a solar energy system? For example, if the panels are to become more efficient in two years, can the panels be replaced so that the support system remain the same?

Panel replacement is possible if the dimensions of the new panels are the same as those of the existing ones. Otherwise, the entire support structure may need to be replaced.

Also, the electrical parameters of more efficient panels are different from those of less efficient ones, so a designer with the appropriate competence must definitely assess whether the inverter needs to be replaced as well.

In conclusion, the reasonableness of equipment replacement must be critically assessed, i.e. whether the increased productivity will cover the investments related to the replacement.

How much less energy is produced from the winter sun? If any?

In winter, the sun is lower, so energy production is smaller but not completely non-existent. In summer, solar panels often produce more electricity than the household needs - the rest of the electricity can be resold by the producer. In winter, however, the missing electricity is purchased directly from the network.

The month with the lowest productivity is usually December when the output is about 10 times lower than during the summer months. However, production will be significantly higher from March, and April-May can sometimes be the months with the best productivity, depending on the year.

If there is unused electricity, what can be done with it? Sold? How does it work?

Start by submitting the connection application of an electricity producer to the network operator. After submitting the application, a connection agreement is concluded with the network operator, under which your electricity meter will be replaced, because you are no longer only a consumer but also a producer, and the records need to be kept for both directions.

When the meter is replaced and the connection work completed, a network agreement of an electricity producer for an indefinite period will be entered into with the same network operator. After concluding the network agreement, the small production contract must be signed with a freely chosen electricity seller, such as Eesti Energia, who will buy the electricity and, if necessary, sell it to you as well.

Eesti Energia buys electricity from producers at an hourly stock exchange price, minus the margin depending on the parameters of the particular producer.

The settlement takes place automatically and the amount paid for the electricity sold to the network is deducted from the customer's electricity bill. If desired, it is possible to select the Green Energy package, which ensures that the purchased electricity is green.

Do panels need maintenance? How to do it properly?

Solar panels are generally considered maintenance-free - winds and rains generally keep them clean enough. In winter, the snow falling on the panels does not damage them, because the electricity produced by the light shining through a thin layer of snow helps to heat up the panels, which in turn causes the snow to slip off or melt.

The general recommendation is to visually assess the condition of the solar panels with some regularity, and to carefully wipe off the dirt that rain and wind have not been able to remove in a longer period.

Get a quote from Eesti Energia