In towns and cities around the world there is a whole lot of real estate that is available for the generation of renewable energy. And the average onlooker, unless looking very closely, wouldn’t even be aware that it is happening.
In the move from a centralised to distributed generation system, the ability to connect behind the meter renewables is key. However, the opportunities with the current generation of renewables are limited. For example, traditional photovoltaic (PV) panels, besides generally not being aesthetically attractive, are generally only roof mounted.
On the other hand, so called building integrated photovoltaics (BIPVs) can be located almost anywhere on the building and should be fully integrated. This opens the way not only for the next generation of building energy management and the achievement of (near) zero energy buildings but also other grid edge opportunities.
“BIPVs are conceived as a way to replace traditional construction materials with energy generating construction materials and as such they are an essential part of the building,” explains Dr Maider Machado, leader of BIPV activities at the Spanish research institute Tecnalia, who is heading up the European PVSITES project.
“They can include roof shingles, windows, ventilated facades or curtain walls and notably also they can include additional functionalities such as thermal insulation, acoustic insulation or water proofing.”
PVSITES for building integrated photovoltaics
BIPVs are not a new technology but one whose time has come. Think for example of Tesla’s solar roof options, which were launched late last year.
According to Machado, approximately 200 BIPV products are currently available in Europe. Most of them are rooftop applications, followed by glazed systems, e.g. for facades or skylights, and also most are based on crystalline silicon technology.
In addition, the technologies have tended to be plagued by other factors such as low efficiencies and high costs, the latter exacerbated by the fast declining costs of traditional solar PV, and it is such issues that PVSITES is aimed to address.
“The project was conceived together with a group of industry partners in the BIPV market to address a clearly identified series of barriers and challenges that are preventing large-scale deployment of the technology,” says Machado. “We know the market is in expansion, driven largely by building regulations, but it isn’t achieving its potential.”
Moreover, new technologies are emerging, in particular bifacial cells or thin-film technology based on amorphous silicon or copper-indium-gallium-selenide (CIGS), which is opening the way for example, for lightweight flexible membranes for rooftop applications.
“If we can address these barriers, we are supporting Europe’s energy efficiency policies and targets for zero energy buildings.”
With support from the EC Horizon 2020 programme, the three and a half-year PVSITES has a number of objectives. These include the delivery of a range of new module technologies, two new inverter technologies, a new building energy management system and a software simulation tool for architects.
In addition, recommendations will be made on issues such as standards and a large effort is put on information dissemination.
All technologies are tested in the lab, before being moved out to the field at six demonstration sites across Europe. These include Tecnalia’s head office building and an industrial building in Spain, a multi-family building in France, a single family building in Belgium, and a carport and an educational building in Switzerland.
“We have aimed to cover different electricity markets, climates and building uses with different architectural implementations and also both new and retrofit situations,” says Machado of the demonstrations.
She adds there also will be demonstration of the new energy management system, which is designed to optimise instantaneous self-consumption in combination with load shifting and/or storage and includes forecasting tools for day ahead planning.
“We believe these features along with generation and storage and other energy efficiency measures are necessary to achieve a zero energy building.”
As an example of the latter, she cites one of the products under development in PVSITES - a semi transparent solar control system for application on skylights and facades. During the winter the system operates as a traditional BIPV system but in summer the radiation is concentrated by a Fresnel lens system to a BIPV module thereby avoiding its entry into the building.
With all products the goal is to achieve a cost target with a 5-7-year payback, depending on the climate, business model, etc.
BIPVs – looking ahead
While PVSITES has clear targets and deliverables to meet, the question of where the building integrated photovoltaics market in general is headed is somewhat nebulous at this stage.
The project’s own analysis estimates that until at least 2020 the market will remain niche, with BIPV technologies accounting for no more than 8% of total PV shipments, or 5GW, by 2020. Europe and the USA are seen as the market leaders with approximately $4.7 bn invested in each.
Machado comments that key will be dissemination of information on BIPVs and she says there is a lot of work to do. “We need to work hard on the relationship with architects, builders and installers and especially the general public. Ultimately, they will be key to reducing the complexities and costs in the market, alongside building regulations and incentive options.”