- Press Release
Bright prospects for the summer solstice

Soaking up the summer sun with solar panels

  • June sun ideally positioned for solar power production.
  • PV production highly effective even in the summer heat thanks to higher peak sun hours.
  • Battery storage and photovoltaic system as an effective means of saving electricity costs and CO2 emissions.

Munich, 22 June 2023 – In June, the position of the sun in the northern hemisphere not only reaches its highest elevation – on the summer solstice on June 21 – but the productivity of photovoltaic (PV) systems is also among the highest compared to the remaining 11 months of the year. An expert from Europe's leading smart energy company, gridX, explains why this is the case and what other important facts about PV systems consumers should know.

"The fact that electricity generation with PV systems is usually most effective in June can be explained quite simply," says Baptiste Feron, Head of Energy Management at gridX. According to the expert, two reasons are decisive: "the days around the northern hemisphere’s summer solstice mark the longest days of the year, equating to the highest number of sunshine hours, or in technical terms peak sun hours. These are the best conditions for solar power production." Just like a PV system’s maximum effectiveness is concentrated in the summer months – around 70 percent of total solar power production in the year usually takes place in the summer months – there are also more effective times throughout the day. In addition to the midday sun, the sun's position in the late morning and early afternoon is also well suited for large-scale electricity production from solar energy.

PV systems can handle the heat

"We often hear concern from non-industry professionals that PV systems do not function properly at high temperatures," says Feron. "This is not completely inaccurate from a technical point of view, as the scorching August heat with temperatures above 30 degrees Celsius does not provide the ideal temperature for operating PV systems," the expert explains. However, the reduction in effectiveness is very minute even in intense heat. In fact, for a normal household with average electricity generation and consumption the drop in output is usually not even noticeable. "High outdoor temperatures reduce PV system performance by a very low percentage range," says Feron. As a rule of thumb, it can be assumed that from 25 degrees Celsius, the effectiveness can decrease up to 0.5 percent per additional degree Celsius. At a temperature of 35 degrees Celsius, an efficiency reduction of around five percent would theoretically be possible. "Particularly in summer, and especially on the sunniest days, this reduction should not be noticeable, because the sheer length of the days and thus the extremely long production time of solar power immediately compensates for the lower efficiency," explains the gridX expert.

Expert tip: Maximize the use of solar power with battery storage

If a solar producer’s feed-in tariff is lower than the import electricity tariff, – this is dependent on regulation and common, for example, in Germany – users have a greater financial incentive to take advantage of these sunnier (as well as the not so sunny) days. This can be done, says Feron, by making use of the flexibility, for example, by storing surplus PV with batteries. According to the expert, this is the most beneficial way to handle locally generated solar power. "To maximize self-consumption of locally generated electricity, everyone who owns or buys a PV system should also add a battery," says Feron. After all, solar production is not only subject to seasonal conditions, but also finds its limits during the course of the day. At night – i.e. when there is no solar irradiance – no electricity is produced. Without storage, conventionally generated electricity must then be drawn from the grid. To minimize reliance on the grid, end users can use batteries to store electricity generated during the day and use it to power the home during the night. The gridX expert states, "maximizing self-generated solar power by combining a PV system with a storage unit not only saves CO2 emissions, but also minimizes your electricity costs. At gridX, we calculated that users can save up to 400 euros per year." Finally, the expert advises to assess different options before making a purchase and to consider the joint purchase of decentralized energy resources (DERs), such as a PV system, battery storage, heat pump and wallbox, in combination with an energy management system (EMS). "Connecting DERs and optimizing the energy flows between them with an energy management system allows management without human intervention: For example, an EV can charge or a heat pump can run as soon as the sun shines. Especially with an increasing number of DERs the EMS adds crucial value," says Feron.

What does energy management look like in private households? Learn more.

About gridX

gridX is Europe's leading smart energy company based in Aachen and Munich. With its IoT platform XENON, gridX enables manufacturer-independent monitoring and management of distributed energy resources. XENON allows partners to develop and scale energy management solutions faster than ever before. By partnering with gridX, Fastned is able to install more charging points at sites without the need for costly grid extensions, and the Viessmann Group is able to offer its customers intelligent and integrated home energy management systems.