Japan’s “Do it Ourselves” model for community power

By Shota Furuya, Institute for Sustainable Energy Policies (ISEP)

The Beam
Published in
7 min readAug 22, 2017


This article was published in The Beam #4 — Subscribe now for more on the topic.

After the Great East Japan Earthquake and the Fukushima nuclear disaster a community group in Tama City took an initiative for a community solar project.

Often, community power innovation arises from adversity. Integrating numerous ideas, crafts and networks, a community solar startup in Tokyo leads the megacities’ community roof-top solar with an innovative participatory installation model.

DiO (Do it Ourselves)

In September 2016, a Tokyo based community solar startup, Tama Empower, released a new participatory installation model for rooftop solar called ‘DiO (Do it Ourselves)’. This model provides customers not only with electricity from PV, but also a deep understanding and a tangible feeling of community ownership of PV.

The scheme of DiO consists of four main pillars:

  1. Building owner’s and tenant’s participation in installation
  2. Cost reduction through process break down and role sharing
  3. Carefully selected solar PV equipment
  4. Institutional operation and maintenance (O&M) support
Professional construction builders serve as the instructors and the participants learn how to build up mounting parts and how to set PV panels on them.

1. Building owner’s and tenant’s participation in installation

In DiO, customers (mostly owners and tenants of commercial buildings, public buildings or private apartment buildings) participate in a training session. Tama Empower gives a short lecture on the significance of renewable energy for the future and some background information on DiO. The professional construction builders then serve as the instructors and the participants learn how to build up mounting parts and how to set PV panels on them. Through this training session, building owners and tenants gain comprehensive knowledge of the solar PV equipment they are going to install. After this session, the customers will build up mounting parts and set PV panels on the roof of their own building thanks to the help of their instructors.

2. Cost reduction through process demystification and role sharing

It is often noted that the cost of solar PV installation is very expensive in Japan. Referring to a research institution’s finding that the most expensive part of the installation is the construction cost, Tama Empower focused on reducing it. By breaking down the whole process of construction, the process was evaluated in three categories: (1) the processes workable by lay people; (2) the processes workable by people trained by the professionals; and (3) the processes workable only by the professionals. Through the standardisation of these three categories in an efficient way, as well as sharing some parts with the participants, DiO were able to reduce the costs of the construction process.

3. Carefully selected solar PV equipment

The solar PV equipment of DiO is carefully selected in order to meet both the durability requirements for the rooftop installation and the simplicity needed for the participatory installation. Specifically, those requirements are fulfilled with the combination of Krannich Solar’s module, K2 Systems’ D-Dome mounting system, and SMA’s inverter and remote monitoring system.

4. Institutional O&M support

Operation and maintenance is an essential part of solar PV. DiO covers it institutionally under a partnership with professional construction builders and electrical engineers. One year after the installation, the construction builder will come again and inspect the system for free. From one year onwards, the owner needs to check the system themselves, and Tama Empower provides the owner a self-inspection manual. In addition, DiO oblige owners to take out insurance.

Skillfully combining those technical and social pieces and integrating them as a comprehensive package, DiO opens up the further possibilities for the roof-top solar PV in urban areas and will increase the reliability of community roof-top solar projects.

Professional construction builders train the participants of the Tamara Empower community.

The story behind the project

One might wonder why and how the DiO model was established. As with many ambitious projects, there were a lot of challenges and adversities along the way.

After the Great East Japan Earthquake and the Fukushima nuclear disaster on March 11th 2011, a community group in Tama City, a west suburban part of Tokyo, took an initiative for a community solar project. Together with the Mayor’s commitment, the group applied for a planning support program by the Ministry of Environment, and the application was successfully adopted in 2012.

They later organised stakeholder meetings in partnership with Tama City, during which they discussed and investigated the feasibility of rooftop solar installation on public facilities such as schools, community centres or publicly-owned apartments. They also investigated the feasibility of installation on the privately-owned apartments around the city, as Tama City is famous for its extensive ‘Tama New Town’ residential area. The bird’s-eye view of the city is almost filled with unharnessed roof-tops, and they dreamed of a Tama City powered by local roof-top solar PV.

However, as they carried forward the feasibility study, it turned out that the possibilities for the use of public facilities is very limited due to the low aseismic capacity of old buildings, inappropriate forms of roof for PV, bad timing of major roof repairs and so on. In addition, privately-owned apartments presented specific difficulties in terms of consensus building among owners and/or tenants. In condominium apartments, the management associations take the responsibility for the decision making. A board meeting is usually held once or twice a year, and the board members change annually. This means that it is almost impossible to reach consensus between dozens or even a hundreds of households in a limited time frame. Even if the board members support the installation, some owners or tenants worry about technical issues such as leaking roofs or durability through typhoons and storms.

Facing those issues, the planning team was stuck. Being a newly established group, they didn’t have extensive knowledge on solar PV technology, and there were only limited technical options at that time. The technology and market maturation, which came from the explosive solar market growth in Japan, would only happen later.

However, the team were persistent in achieving their vision. As a result, the newly established local business entity, Tama Denryoku, successfully installed a total of 610 kW distributed solar PV in 13 places around the city — on a university building, schools, a house for elderly people, a community center, a private company’s building and a museum.

Through the planning and development process, they experienced dozens of unexpected problems and learned a lot about the real possibilities and barriers of community solar projects in urban areas. After the first project, they decided to pause and think through further activities carefully.

One of the leaders of the team, Yuichiro Yamakawa, decided to develop a new way of delivering community solar projects that reflected Tama Denryoku’s experience. Together with colleagues from various backgrounds, he established a new startup company, Tama Empower, and carefully developed the new model of community solar that provides both robust technical reliability and tangible social inclusion. DiO is the solution that met those requirements.

Adversity as source of innovation

I have in fact supported and facilitated the initiative from the beginning and followed the long and winding process. I shared the community’s dreams, difficulties and persistence. What I learned from the process is that every experience, including adversity, will be a solid base for the future innovation of community power. When you face adversity, dilemma or contradiction in the process of community power planning, they are not necessarily negative events, rather, you might recognise them as positive opportunities for innovation.

ISEP recently moved to a new office building as the owner, and immediately we decided to install solar PV on the roof. As you might expect, we installed it in DiO, and really enjoy it!

For more information, visit tamaempower.co.jp and tdio.tamaempower.co.jp.


Researcher, Institute for Sustainable Energy Policies

Shota Furuya is a researcher at the Institute for Sustainable Energy Policies (ISEP). Shota is working on research and advocacy in order to realise a sustainable and creative energy society. He has worked on community based renewable energy development in Japan and focusses on the process in which different local stakeholders share a sustainable and creative future vision.



The Beam

The Beam unites the changemakers and innovators in the Global Climate Action movement to amplify their voices. Contact us: thebeam@the-beam.com