Urban PV up-scale: Implementation of photovoltaics in urban developments

The last 15 years have seen the implementation of large-scale PV projects in urban developments across Europe. In this, the second of her three articles on urban PV, Donna Munro takes a look at some of these projects, and at the elements that have made them a success.

As sustainability becomes a more significant issue for the construction and property development industries, the installation of photovoltaic systems on buildings is gradually becoming part of the ‘standard’ building and development process. This shift will bring new challenges to the PV sector and the construction/development industries, which are not yet used to working together. Furthermore, as the implementation of renewables becomes more widespread, it is becoming increasingly common for design teams that have no previous experience of solar to be asked to include PV in a development.

What routes can lead to the successful implementation of photovoltaic installations within the urban renewal and development process, and what lessons can we learn from past projects?

The urban development process tends to be complex, with a lot of issues needing to be taken into account. Within the overall development of an area, PV has a very small role and cannot be expected to be high on the priority list of everyone concerned. However, as a solar technology, the effectiveness of PV is highly dependent on solar orientation and shading. This means that many aspects of the development from the layout of the roads to the building massing and shape of the roofs will crucially affect the feasibility and performance of any PV systems installed. The sizing and layout of the electricity supply network may also need to take any embedded generation such as PV into account. However, in a large development planners may define the site layout, and infrastructure such as roads and electricity supply may even be installed before developers are appointed.

The decision to include PV is often made at a late stage. In many cases developers or housing associations that have become interested in PV have looked at the projects they are already working on and selected areas where PV could be installed on the basis that the site concerned happens to have a good solar layout. Many other sites are not suitable for PV due to factors that could have been changed if they had been considered at an earlier stage.

Early to rise

Photovoltaics, unlike many other technologies included in buildings, is best taken into consideration right from the beginning. However, the urban planners, consultants and developers involved in the initial project definition may well not have any solar experience. Advice from a specialist with solar experience can enhance the feasibility of installing PV and optimize the cost and performance of the PV. As experience is gained across the industry, and understanding of PV and its implications for site layout and planning become a standard part of planners’ and developers’ repertoires, all will become easier. Until then, a solar specialist needs to be brought in early on in the process.

Once a decision has been made to allow for the inclusion of solar technologies in a building development and a ‘solar friendly’ layout adopted, a number of elements will be required to realise the solar installations:

  • Money: Can it come out of the existing budget? If not, can money be raised from external funding sources or innovative financing?

  • Time: The implementation of renewable energy projects has to fit within the construction timetable or there will be major problems and extra costs. If the PV is added to the design late in the day it can result in compromises having to be made.

  • Technical knowledge: This will be needed in the project team, from knowledge of electrical design to the effect on the structural design, to negotiating the sale of electricity.

  • Inclusion in the work plan for the entire project team: Installation of a PV system will affect other members of the team, not just the PV sub-contractor, and they need to allow for it.

  • Transmission links: A connection to the local electricity network will be needed.

  • Enthusiasm: Last but not least, there has to be some enthusiasm for renewable energy or the project will not result in the hoped-for emissions reductions. An obligation from above, implemented by a poorly informed design team, is likely to lead to a poor design.

Time, knowledge and inclusion in the work plan all go together. Knowledge too late in the day is of no use. Knowing something but not including it in someone’s work plan is of no use either. The challenge is to transfer the right knowledge to the right people in time for inclusion in the work plan, and the earlier the better.


A project in France – at Lyon-Confluence – shown on page 110, gives an example of the successful transfer of knowledge. This project learnt from previous smaller projects in the Lyon area, such as the Les Hauts de Feuilly housing development where PV was brought in fairly late after developers had been appointed and the site layout fixed. PV was able to be installed on a group of houses at Les Hauts de Feuilly, most of which had a good orientation. However, the orientation varies and is not optimal for all houses. Grid connection was also considered late and additional connection points had to be retrofitted at the utilities’ cost.

Other examples of technical information being passed on effectively include the Stad van der Zon, in the Netherlands. Here a new town area is being developed with PV on houses constructed by different architects, developers and builders. As soon as the detailed urban design and architectural aspects were in sight, a PV workshop was organized for architects and PV system manufacturers, resulting in draft designs and a book. The workshop was repeated in 2002. From a technical point of view, there were no problems in the design and realization of this ambitious project. There have, however, been major problems with the funding, as well as incompatibilities between the development timetable and the timescales required under the final funding arrangements.

Many different approaches can be used to transfer knowledge and experience, but the approach used has to fit in with the development process in the country concerned. It is surprising how significant the differences are between different countries. Even the term ‘town planning’ means different things in different places.

In Germany, development is mainly down to investors and developers, and municipalities are less involved with the development process than they are in the Netherlands. Nonetheless, German municipalities have been willing to conduct detailed analysis of urban renewal or development areas and use the results to assist investors. At Gelsenkirchen-Bismark, for example, an overall urban plan was developed which included a simulation of shading and solar irradiation on building surfaces. To avoid major shading of the building surfaces an advisory committee was formed to assist individual investors.

Also in Germany, a solar urban master plan was prepared for Berlin in order to determine the solar potentials of the different city quarters. The results were brought together with an urban renewal programme aimed at stimulating investment.

In Kirklees in the UK, the municipal environment unit brought together developers and PV specialists to enable the creation of PV projects. One of the developers involved stated this was crucial in getting them started with PV, but they now have sufficient experience to start projects on their own.


Difficulties in fitting a PV project into a development timetable can cause many problems. If PV is added late in the timetable it will often lead to less-than-optimal designs; if external funding is required, another level of complexity is added with difficulties matching dates of funding rounds, and restrictions on the dates that money must be claimed by. It may even be necessary to have two versions of the design, with implementation of the PV version being dependent on an award of funding. Major developments have many constraints and hurdles to overcome, and PV is only a minor part of the overall picture. Waiting for PV funding cannot drive the timetable.

Nonetheless, despite some potential difficulties, the inclusion of good quality photovoltaic projects in major developments is in some ways much easier than people think. Exposure to the technology often leads to enthusiasm. Results from many projects suggest that developers and architects are often surprised at how easy a technology PV is to design with and install. The key is spotting issues at the right time.

As more and more PV projects are implemented, so PV will become part of the standard repertoire of architects and engineers. There may also be a reduced level of uncertainty on the part of clients and other members of the project team, which should lead to further cost reductions.


PV is undoubtedly expensive. Most urban-scale PV projects to date have obtained some level of capital funding subsidy, but subsidies are becoming harder to obtain. In some countries their role has been replaced by funding paid via premium rate feed-in tariffs for renewable energy. This guaranteed income can allow finance to be obtained through loans.

Sources of funding range from the European Commission (which tends to fund larger projects but not individual buildings), national or regional renewables programmes, which tend to be more accessible to smaller projects, and local municipal or utility funding. Those municipalities that have created renewables funds, such as Kirklees – which decided to set up the Kirklees Council Renewable Energy Capital Fund in 2000 – have been able to get a range of projects going in their area and start up local supply and installation companies.

If no subsidies are available the full costs may be met by developers or builders, and then passed on to the purchasers of the building. If there is an obligation that all new buildings in an area install renewables, then anyone who wishes to own a building in that area has no option but to pay the cost. If there is no obligation then such buildings have to be marketed at a premium price justified by their sustainable design. The viability of that depends on the local market and preferences of purchasers.

In some locations, such as London (UK), there is evidence of higher property values for properties with PV systems. Here, some developers obliged to install renewables have found PV the most cost-effective solution because it does not take up any space in the house, and the cost of the space needed for a hot water tank for solar water heating outweighs the higher outlay for PV. Some projects have raised money by selling shares. The financial feasibility of this is improved in countries where a premium feed-in tariff is paid for electricity from PV.

In Austria, a 10.44 kWp communal PV power plant on the roof of the offices of utility company Feistritzwerke-Steweag was the first PV power plant in Austria realised through a shareholder programme. The company Feistritzwerke GmbH co-ordinated the shareholder programme. This project made it possible for environmentally engaged people to own a share of a PV power plant. Initially, sales of share certificates were slow. The project manager put a lot of effort into advertising the project which raised interest among the local population. About 2500 people requested information about photovoltaics and in the end, 68 people bought shares which financed 80% of the costs; the remaining 20% was financed by the utility.

In Freiburg, Germany, financial difficulties were encountered during the development of the Solarsiedlung am Schlierberg eco-housing estate. These were solved by starting a fund, called ‘1. Solar Fond Freiburg,’ with an invitation for subscription to share certificates of €5000 each. The shareholders were primarily private citizens who wished to make a sustainable long-term investment. The total investment was €1.5 million.

This new financing model was the key to success. The first one was followed by three other investment funds with a total investment of €3 million each. In total, 15 houses belong to these four solar funds. The houses are rented out for an average of €11/m2 (per month) and the funds are traditional closed-end real estate funds. Their average interest yield is 5%–6%, which is about average for this type of investment.

The roof-integrated PV systems were marketed separately. Either the homeowners or other investors purchased them. A return on investment is granted by the 20-year payment of the feed-in-tariff under Germany’s National Renewable Energy Act.

Grid connection

Photovoltaic systems in buildings are part of the building electricity distribution system and hence are normally connected to the local distribution grid. Technically, connection to the grid is straightforward so long as the local grid can absorb the extra power without exceeding voltage limits. However, agreement to connect to the grid must be obtained from the local Distribution Network Operator (DNO).

In addition, a contract for the sale of electricity, at an agreed tariff, is normally required unless extra electricity is spilt to the grid with no payment obtained, as is often the case in the UK. Significant delays and additional costs can arise if discussions with the DNO are left too late.

Large PV systems, or large groups of systems, should be taken into account during the design phase of the distribution grid in order to correctly size the new distribution grid and avoid any additional infrastructure work once buildings are completed. Attention should be paid to the location of medium voltage/low voltage (MV/LV) transformers and the size of transformer feeders to make sure that each PV system can be connected to a suitably robust LV grid. Single systems or small groups of systems can normally be connected to the existing grid without any modifications.

Dedicated connection points may be required for contractual reasons. For instance in France, in order to benefit from the feed-in tariff for all of the energy produced by a PV system, the utility has to create an additional, dedicated connection point. So for a new development of houses with PV the DNO may need two connection points for each house, rather than the normal one. Unfortunately, the current administrative system officially requires detailed information about power plants before the DNO can take them into account. As the detailed information required is unlikely to be available during the infrastructure design phase, there is a potential problem.

At Les Hauts de Feuilly, France, a group of 19 houses with PV roofs needed dedicated connections to the grid. However, the DNO was not officially informed of this until the houses were complete. The problem delayed the commissioning of all PV systems while dedicated connection points were installed. In this case the extra costs involved were borne by the DNO, rather than the inhabitants, as the power of each PV system was below a certain level.

At the subsequent Confluence project in Lyon the designers were aware of this potential problem so organized a technical meeting with the DNO to find a way, during the design phase of the distribution grid, to take into account the fact that several buildings would be equipped with PV.

Having individual building owners regarded as generators, with all the associated regulatory requirements, is a very recent phenomenon. Appropriate administrative procedures are not yet in existence for dealing with groups of small identical generators. Standard procedures for export of electricity normally require complicated and time-consuming forms to be filled in. However, if the forms are to be completed by individual householders and this is left until the houses are occupied, problems and delays are likely to result.

Experience at Les Hauts de Feuilly housing development in France led to suggestions that a developer that chooses to install PV systems on its buildings should assist future home owners until the commissioning of the PV system. In particular, developers should make sure that future home owners have signed the contract for the connection of the PV system to the grid with the DNO and the contract for the purchase of the electricity produced at a specific feed-in tariff.

Donna Munro is a renewable energy consultant working with Halcrow Group Ltd.
e-mail: munro.donna@virgin.net

Case study: Lyon-Confluence, Lyon, France

At the heart of the French city of Lyon is the peninsula formed by the Rhône and Saône, the city’s two rivers. Lyon-Confluence is the name of the southern part of this peninsula. It has for a long time been given over to industry and transport logistics. The area is now undergoing radical changes, which ultimately will double the area of Lyon’s city centre. A 30-year plan includes more than 1,200,000 m2 of new buildings including housing, commercial, services and cultural infrastructure, plus the refurbishment of roughly 60,000 m2 of an existing residential area.

Renewables were not initially part of the plan, but a new municipality was elected in 2001 and brought with it a political impetus toward sustainability. In 2003, an environmental study of the Confluence project concluded that energy efficiency and the use of renewable energy sources were its main weaknesses.

In order to correct this, SEM Lyon-Confluence, the semi-public company in charge of city planning, set up an informal group of local experts to submit ideas and help to define the energy strategy of the project. Discussions focused on the energy performance of buildings and the relevance of renewable energy sources. However, fears of cost over-runs and of innovation preventing the commercialization of buildings led some participants to propose designing buildings just slightly more efficient than the regulations and equipped only with solar thermal collectors for domestic hot water.

An opportunity then arose to submit a proposal under the European Commission’s CONCERTO initiative, which was set up to support innovative urban projects and define ambitious goals in terms of energy efficiency and renewable energy sources. In 2004 the RENAISSANCE project was agreed relating to the first housing to be constructed in the area. Today, three sections of estate with eco-buildings equipped with renewable energy systems are under construction, following the architectural, environmental and energy guidelines provided. The buildings will be equipped with wood chip-fired boilers, solar thermal systems and PV.

The PV contribution consists of 80 kWp on the A section developed by Nexity Apollonia, 100 kWp on the B section developed by Manignan Bouwfonds, and 50 kWp on the C section developed by ING Real Estate.

The experience gained within RENAISSANCE led SEM Lyon-Confluence to upgrade its guidelines for the construction of other buildings to include requirements to install PV. Thus PV will also be installed on other emblematic buildings in this area, including the headquarters of Le Progrès, the local newspaper, the HQ of Eiffage, a large building company, the Regional Council building, and the Natural History Museum.

Although the guidelines for the selection of developers set out some requirements regarding the need to have an engineering office specializing in energy efficiency and renewable energy systems in the team, it appeared that none of them had any serious experience in PV.

Fortunately this gap was able to be addressed as part of the RENAISSANCE project. A team of local specialists was set up to assist engineering offices and developers at all stages of the project, from the preliminary design to the commissioning of PV systems. This local team also organized site visits and training sessions and is helping developers to deal with a complex financial scheme with multiple sources of funding.

Over a two-year period, meetings and workshops were organized to assist architects, engineering offices and developers to finalize building design. Discussions focused first on the building envelopes, in order to reach the energy consumption targets without impacting the architectural appearance of buildings. In the second stage, discussions focused on wood chip-fired boilers and PV systems. At first these were seen by developers as irrelevant and impractical for this kind of urban project.

However, a series of site visits, training courses and technical analysis finally convinced the developers that PV was not a difficult technology to deal with, although some questions about price remained. The success of the commercialization of the first dwellings in 2006 resolved these discussions about the price of PV and convinced the developers that energy-efficient buildings have a market. Indeed, no negative feedback was received during the commercialization of the dwellings.

Case study by Bruno Gaiddon of HESPUL
e-mail: bruno.gaiddon@hespul.org


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