1. Operate small wastewater treatment plants with solar power: Why makes sense?

Many of these objects can offer good conditions for photovoltaic systems due to their roof areas or open land areas. In extreme cases (as with some mountain huts) even an independent power supply is essential.

Here, the solar system with power storage can not only provide the energy for the building, but also the function of a technical one small sewage treatment plant guarantee.

Depending on the system, these systems require more or less electricity for:

• pump
• Engines & ventilation systems
• the electronic control

The power consumption here is usually relatively continuous throughout the day, since pumps or compressors work at intervals. This means that the solar power generated can be used directly during the day and the excess energy stored in the batteries can be used up at night.

So when you plan your solar system, you should definitely not forget the consumption of the small sewage treatment plant. The purification system is an easily calculable consumer, which, as mentioned, consumes electricity continuously.

With other consumers, such as a washing machine or an electric stove, there are high peak loads. Partly it is recommended here that such strong consumers in the sunshine hours of the day – if, under certain circumstances, more energy is generated than in the solar storage can be included. Such “problems” do not exist when calculating the energy consumption of a small sewage treatment plant. The systems can therefore be integrated very easily into the solar concept.

2. Are there any sewage treatment plants with photovoltaic system?

A purification system, which directly with Photovoltaic is offered by the manufacturer Kingspan Group. The Kingspan Modular BioDisc® offers significant savings in energy costs thanks to the optional solar support.

The models can have a modular structure and cover biological wastewater treatment for 250 to 2,500 people. There is not only a modern remote monitoring solution including an automatic alarm function, but also the solar power supply mentioned. According to the manufacturer, this allows the system to produce up to 80 percent of the energy required https://www.kingspan.com/de/de-de/product-groups/wastewater-treatment-biological-wastewaterreinigu/downloads/biodisc-bh-bl).

A larger project was planned by the waste water association “Zellinger Becken”. With 227 modules, a peak output of 87 kilowatts and an annual yield of over 92,000 kilowatt hours (kWh), the municipal sewage treatment plant would be supplied with solar power.

The self-consumption rate would be over 96 percent. Together with the existing CHP, which generates energy with the digester gas from the sewage treatment plant, around 44 percent of the energy can be generated by the company itself. The proportion of solar energy here is 14 percent and the solar system would be financed after 12 years through the electricity cost savings (https://www.mainpost.de/regional/main-spessart/klaeranlage-mit-photovoltaik-stromkosten-sparen-art-10232635).