Common Misconceptions About Residential PV

More and more people want to invest in photovoltaic arrays and battery storage systems. However, the German Consumer Association said that many misunderstandings may eventually lead to consumer disappointment.

Home demand for rooftop photovoltaic systems and residential batteries continues to grow. In order to meet the expectations of building owners, the German consumer association Verbraucherzentrale NRW is trying to clear up misconceptions about photovoltaic installations that can disappoint professional consumers.

Verbraucherzentrale NRW energy digital transformation analyst S?ren Demandt said: "It is very important that people can clearly realize their personal goals for using photovoltaics, and then discover more information about other aspects. In this way, Disappointment can be avoided, and solar energy can be used truly efficiently."

The first misconception is that people are promised that they can be self-sufficient with photovoltaics and storage systems. This is not the case, as photovoltaic systems and home energy storage solutions can only meet a certain percentage of a household's annual electricity supply.

The degree of self-sufficiency achievable in a home ranges from 25% to 90%, depending on the level of electricity consumption and whether a storage system is installed. Especially in the winter months, demandt said, there is not enough solar power generation, so electricity must be purchased from the grid. Full self-sufficiency can only be achieved with additional seasonal storage, such as hydrogen electricity.

"However, this is technically very complex and makes little economic sense for residential units," Demandt said.

Another misconception is that photovoltaic systems are only valuable when combined with batteries. Some homeowners seem to think that connecting solar to the grid is not an attractive option from an economic standpoint.

"PV systems can still be economically valuable even without storage," Demandt said. "The viability of installing batteries for a PV system depends on a number of factors—primarily household consumption and electricity costs."

Therefore, homeowners should check their power consumption levels without the storage system installed. They can compare the higher level of electricity consumption achieved after installing the battery storage system with the actual electricity bills incurred.

Verbraucherzentrale NRW disagrees with the opinion that south-facing roofs are always more suitable for installing photovoltaic systems than east-west facing roofs. Photovoltaic power generation not only pursues as much power output as possible, but also needs to be able to meet continuous power demand. Compared with the south-facing roof, the photovoltaic system installed on the east-west facing roof has only about 80% of its annual power generation. However, the power generated by a solar system installed on an east-west facing roof can be spread over the course of the day, as the system still gets a lot of sunlight in the morning and evening.

Many homeowners do not have a roof to install photovoltaic equipment, and often they will consider investing in plug-in solar equipment. Such devices can be installed both on the balcony and in the garden. However, if occupants expect them to be able to power household appliances such as coffee makers, they may be disappointed.

"These panels are particularly well-suited to covering the base load of a home," explains Demandt, "where the electricity is used directly, for example, for a phone, internet router or alarm clock radio."

More electricity demand will be provided by the grid. For example, a coffee machine needs about 2000 W of heat to boil water and heat it. According to Verbraucherzentrale NRW, this cannot be achieved with balcony PV modules alone.