Large-scale solar rooftop simulations to stimulate decentralised power generation

Walking through the streets of two Hungarian settlements in North-Western Hungary, there is one similarity between DáG with 350 and MáRIAHALOM 250 houses: none of the roofs is covered by solar panels for electricity production, while sunflower fields indicate that there is an abundance of solar irradiance.

One reason might be that household energy costs in Hungary covered heating costs by 71,7% considering the total household energy expenses in 2018 according to the statistics of EUROSTAT. This is the 4th highest in Europe, meaning that an average Hungarian family spends more on heating than those living in Finland, Denmark or Sweden - all located on a much colder climate. In addition, all the citizens living in the neighbouring countries to the north of Hungary spend less on heating. A vast portion of the building stock was built pre-1980 with low energy performance standards and it is estimated that 70%-90% of them needs renovation.

Parallel to the extremely high proportion of heating costs (and extremely rundown building stocks) the price of electricity in Hungary is the second cheapest in Europe, half of the EU average and 37% of the German or Danish fee for each kilowatt-hour power.

In this regard, the initiatives taken in some European Member States such as Energiesprong in the Netherlands, the New Greens Saving initiative in the Czech Republic and district renovation schemes in Lithuania have been successful to fund renovations at the local level but my intention is not focusing on energy efficiency but rather on clean, local electricity production.

In fact the local power generation is gaining momentum in Hungary too. According to the Google Trends statistics, over the last 5 years, there has been a continuously increasing interest among Hungarians searching for the keyword ?napelem” – solar panels.

Looking at the official statistics, by the end of 2019, 462 MW of solar rooftop installation was operating in Hungary below 50kW individual capacity, owned by individuals and businesses. Based on the statistics in 2019, 7,88 kW was the average capacity of the new systems – this is about 25-30 panels assuming 270-300W panels generally available on the market. 85 % of them were installed by private individuals at 14.500 locations with 93 MW capacity. As the number of the small power plants were 20.500 by the end of 2017, 30.000 in 2018, one may summarize that there are about 55-60.000 roofs in Hungary partly covered with solar panels.

There is a huge potential for growth in the Hungarian market, considering the over 4.400.000 building stock, only 1% of their roofs are utilized so far. As panel prices are decreasing (by an astonishing 82% over the last decade) and the Climate and Nature Conservation Action Plan of the Hungarian government foresees an additional 200.000 solar rooftop systems in the coming 10 years, one can agree that such a substantial change in local electricity generation will have considerable impacts on the local grid.

But before this happens, before deploying Gigawatt capacities of solar rooftop systems, is there any way to produce data that helps organisations accelerate decarbonisation? Does it make sense to analyse the built environment across the country or even the continent to enable decision-makers, local municipalities to prioritise their investment in sites for solar panels?

In advanced economies in Europe and North-America, solar PV rooftop simulators have been put to effective use for many years to aid the assessment of conditions in specific cities, with the prospect of establishing rooftop PV markets. These simulators use cutting-edge technology that combines know-how in remote sensing, high-performance data processing, 3D building footprint generation and solar irradiation modelling. These systems often combine LiDAR radar data and / or stereoscopic image processing to evaluate the shape of buildings.

One of these massive campaigns was Google’s Project Sunroof, launched in 2015. The aim of this program was to provide a tool that allows people to see how affordable solar can be. One of the reasons why this solar calculator is so successful at promoting solar panel installations is its user-friendly visual aids. These visual aids allow interested homeowners to see the potential savings of solar for their homes. There are many features about this solar calculator that make it appealing. Some of these include Google’s home images, roof shading technology and solar investment savings calculations.

Local municipalities and regional governments are also taking their shares in providing customized information. Lambeth is one of many councils in the UK and globally that have declared a climate emergency. It is aiming to become carbon-neutral by 2030. Spatial data specialist Energeo assessed almost 100,000 buildings and identified 40,000 sites that are suitable for solar photovoltaic panels. The company uses automated techniques to extract detailed information from data sources and provide snapshots for individual properties relating to the roof size and pitch, solar yield, revenue potential, CO2 savings and listed building status. The analysis revealed over 1,325,000 m2 suitable unused roof area.

The sunny city of Lisboa in Portugal also made SOLIS - Lisbon Solar Platform, with the mission of promoting a wide acceptance and massive adoption of solar technology in Lisbon society, approaching towards the emergence and consolidation of a culture and spirit of solar citizenship.

Lisboa Cidade Solar pursues ambitious goals, in particular: In 2021, 8 MW of cumulative photovoltaic capacity installed in buildings and 2 MW PV to supply buses and vehicles for the collection of electric waste; In 2030, 103 MW of total cumulative photovoltaic capacity. SOLIS offers you three different maps, with the possibility of three levels of territorial visualization - the city, the parish and the building: Solar radiation map; Solar electricity map; Map of photovoltaic solar installations.

Dutch solar energy is among the fastest-growing renewable energy sources in Europe. In 2018, the Netherlands reached 4,400 megawatts of installed solar energy capacity, increasing the installed capacity by 1,500 megawatts relative to the prior year (50% year-on-year). Over the last couple of years, residential rooftop solar was the main source. In 2018, almost 2,300 MW of installed capacity related to residential rooftop solar. Zonatlas is committed to making the Netherlands more sustainable by calculating the sun potential of 13.5 million Dutch roofs. Is your roof less suitable? There are often plenty of other options. The platform also helps to find your local energy cooperative. On the Zonatlas map, you can see which neighbours of yours can also place solar panels. 

However, commercial rooftop solar is gaining momentum. Out of the 1,500 MW increase in 2018, almost 530 MW was installed on commercial and utility roofs. The Rooftop Solar Tool has been created with the cooperation of Deloitte, to provide you insights into the commercial rooftop solar potential in the Netherlands.

Solar potential registers / cadasters as free web-based tools are widely available at German and Austrian cities, which support locals in deciding whether and how they can convert their roof to use solar energy. The use of online applications is free of charge.

Mapdwell is another professional approach from the other side of the Atlantic Ocean. They are a group of academics and researchers from the Massachusetts Institute of Technology (M.I.T.) and top professionals– working actively with communities, municipalities, and government agencies to help them disseminate knowledge and obtain sustainability.

The Mapdwell Project is supplying communities with information that will drive sustainable practices, community awareness, energy efficiency, and smart development through the aggregate effort of individuals. By transforming accurate, open, and unbiased information into education and action, the project proposes an organic approach to the fossil fuel dilemma. The Mapdwell team works at the intersection of data, design, and technology to craft innovative and intuitive analysis, assessment, and visualization tools –both at building and context levels– for urban and non-urban regions and systems. Their system covers Boston, Portland, Boulder, Cambridge MA, Washington, San Francisco and three cities in Chile.

If you want to dive deeper into the science and practical applications of solar simulators, Kanters, Jouri, Maria Wall and Elisabeth Kjellsson (2014) compared the outputs and impacts of 19 solar simulators in 8 countries in their article "The solar map as a knowledge base for solar energy use", Energy Procedia, Vol. 48(0), pp. 1597–606. International Renewable Energy Agency investigated further the findings of this report and published "Solar simulators: Application to developing cities" in 2019.

There is no lack of Hungarian initiatives for such remote sensing applications. This year Zoltán Biber and Gábor Szujó were placed in the top 8 out of 220 teams in MVM Edison 2020 startup application program with their self-developed MyEnerGIS service! Their intention is to provide similar systems as the ones listed above – according to their video interview with the startup competition organizers.

Users always have to note that the results of the analysis of the solar potential cadastre are based on an automated process, and the results serve only as initial information, but they do not replace specialist advice from a qualified installer. To move toward a more reliable specific data, affordable drones provide a practical solution for the inspection of solar sites, from residential to utility-scale. Drones support business efforts to avoid hazardous and often expensive inspection man-hours, reduce costs for maintenance and repairs, and maximize energy production. Measure, Dronedeploy, Above, Sitemark and Dronebase are among the several other service providers in this field.

There are two European startups, supported by EIT: the European Institute of Innovation and Technology, they both offer customized solutions for roof-assessments and lead generations. PVStream is offering a flat-rate monthly subscription for rooftop system modelling and electric design, while the Spanish Ezzing is cooperating with major energy companies and offering a full spectrum of customer relationship management along the solar power supply chain.

Going back to the two Hungarian villages in Komárom-Esztergom County. The two villages are only 20 kms distance from each other, but the solar energy potential is twice better in Dág (the bottom village with North-South oriented streets) than in Máriahalom (seen left, with mainly East-West oriented streets).

One study conducted in 2008 by the ELTE University – yes, it is not mistyped date, 12 years ago – revealed that there are settlements in the region with spatial circumstances and given the structure of streets and unfortunate lot-allocation, that’s why the majority of buildings have no or limited roof area facing the south. Individuals’ dwelling decisions hold the potential for driving sustainability. However, citizens often lack the necessary tools to help their decision-making. The purpose of my collection was to generate ideas and raise the wide range of tools available to support individuals, businesses and decision-makers.