Thesis work - Impact of aggregated plug-in household solar PV on low and medium voltage grids

Are you a student looking to apply your knowledge to real-world solutions that support the energy transition? With us, you will have the opportunity to complete your thesis project close to the business, working alongside experienced specialists and tackling challenges where your ideas and perspectives can make a real difference. 

Vattenfall R&D is responsible for conducting business driven technical development that creates value for the company and helps us realize our strategy. We develop cost effective, safe and sustainable solutions to improve the infrastructure of Vattenfall assets including Hydro, Wind, Nuclear, SKB, Heat, and Distribution. 

The connection of plug-in household PV systems and balcony solar installations has increased in recent years across many European countries, where approximately 780,000 installations have been registered.  These systems typically consist of one or a few solar panels connected to the grid through a microinverter, which is then plugged directly into a customer's electrical outlet.

Although the individually connected power per customer is relatively low, widespread adoption can result in a significant amount of aggregated generation. Especially in densely populated areas, the combined production from many small-scale resources could potentially lead to power flow issues, voltage variations, instability due to unbalanced loads, and other adverse effects on the power grid. This raises the question: what impact will the connection of plug-in household solar panels have on low- and medium-voltage grids? This is the question that this thesis aims to answer.

This thesis will investigate questions such as: At what penetration level of household PV systems does grid instability occur? What effects can these installations have on both the low- and medium-voltage grid?

The analysis will be carried out using several methods, including a literature review and grid stability studies conducted in simulation software such as PowerFactory or Simulink.

This thesis work is for 1 student. 

We are looking for student(s) who are about to complete their academic studies and are eager to apply their knowledge in a real-world setting through a thesis project at Vattenfall. You are someone who shares our values and identifies with our principles: Active, Open, Positive and Safety. 

We see that you have:

• Education – Master of Science in Electric Power Engineering, Renewable Energy or similar programs 
• Fluency in written and spoken English 

Scope - 30 credits

• Start date: 2027-01-15 or by agreement
• Location: Solna
• Application – Submit a single file containing your CV and a copy of your academic transcripts. Please note that only one file can be uploaded with your application, so it is important that all required information is combined into the same document.
• Application deadline: 2026-10-18, the hiring process is ongoing, therefore please apply as soon as possible,
• Contact person and supervisor at Vattenfall: Marcus Seisay, marcus.seisay@vattenfall.com +46702570472 and Cathrina Bergsjö, cathrina.bergsjoe@vattenfall.com +46702793760

Diversity and Inclusion – In Everything We Do 

At Vattenfall, we value being Active, Positive, Open, and Safety-conscious. We are looking for employees who share our vision and can contribute to strengthening our company culture. We believe that diversity helps build a more successful and attractive company, and we strive to be role models in diversity and inclusion. Vattenfall actively works to ensure that all employees have equal opportunities and rights, regardless of age, ethnic or cultural background, gender identity, religion or belief, sexual orientation, or disability. Read more about how we work with diversity and inclusion here. 

Vattenfall is part of Sweden’s critical infrastructure, and many of our positions are therefore classified from a security perspective. If this position is security-classified, a security screening will be conducted prior to employment in accordance with the Swedish Security Protection Act. 

Vattenfall is a leading European energy company serving approximately 12 million customers and employing around 21,000 people. We believe there is a way to build a future where everyone can choose fossil-free ways to move, make, and live.