Solar resource map

The solar resource map is an interactive map available to all via the website www.cadastresolaire.mc . It allows users to easily and effectively identify, for every roof in Monaco, the potential solar resource, the exploitable area on which photovoltaic panels could be installed, and possible annual electricity production. It is an innovative tool designed to promote sustainable development in the Principality, specifically the development of solar energy.

Solar energy is one of the renewable energy sources available to Monaco, and it is one which has seen a steady decline in production costs over the last 20 years.

This tool offers owners, building managers and individuals the ability to view at a glance the data they need to decide whether to install solar panels on the roof of their building.

It also provides all of the information required to take the next steps: install solar panels, request authorisation to carry out work, or even apply for a grant to install solar photovoltaic panels :

FAQ 

THE SOLAR RESOURCE MAP 

Why is my building not shown on the solar resource map?

The solar resource map identifies building locations using the database belonging to the Principality of Monaco’s Urban Planning Office. The available aerial photographs are updated approximately every three years.

If there is no information about your building’s solar potential, please contact the Mission for Energy Transition , which can offer guidance and answer any questions you may have.

Why is my building’s postal address wrong?

The solar resource map’s address service uses data from Google Maps . While this data is reliable and is continually being improved, it is, however, not entirely free of errors, particularly in rural areas. Address errors can be reported to Google via the Google Maps website.

The postal address shown on the map is included for information purposes only, and does not in any way affect the quality of the solar potential calculation. In the event of an inconsistency between the building clicked on and the address shown, it is the building clicked on which is correct.

Why is there a discrepancy between the solar potential layer and the aerial photography on the base map?

There are two main reasons for this discrepancy:

• The aerial photography is not always perfectly geolocated. When aerial photographs are taken, only roofs that are positioned vertically beneath the aircraft can be seen perfectly from above. The others appear at an angle, and corrections have to be made to counter the parallax effect. These corrections are not always perfect and can create a discrepancy compared with the true position of the roof.
• The solar resource map layer has been contoured using building footprints extracted from the database belonging to the Principality of Monaco’s Urban Planning Office (see Why is my building not shown on the solar resource map? ). This is a default choice that has been made to compensate for the lack of data on roof contours. However, it is the roofs which are visible on the aerial photographs, not building footprints. Differences are visible where there are roof overhangs or covered areas such as carports or covered courtyards.
• What is solar potential?
• Solar potential is the solar energy received on a roof over the course of a full year. It is measured in kilowatt hours per square metre, or in kilowatt hours if it is added up across the entire surface area of the roof. The solar potential is the energy available, with no assumptions made about how this energy will be used, nor about how efficient it will be to use it.
• The solar potential shown on the solar resource map is representative of the typical meteorological conditions experienced in the last 20 years. It should be interpreted as an average measurement which will, in practice, fluctuate from year to year depending on actual levels of sunshine. It is nonetheless a very useful indicator, since solar panels are expected to remain on roofs for more than 20 years. Among other things, it is used to calculate economic viability, to determine whether installation costs can be amortised over service life.

How is the solar potential of my roof calculated?

Solar potential is calculated for each square metre of each roof in the country. At each of these locations, the sun’s path is calculated on an hour-by-hour basis over the course of a full year, and then added up to obtain a cumulative total for the year, which is the solar potential of the given location.

In calculating solar potential, the following specific factors are taken into account:

• Shade resulting from structures on the roof (dormer windows, chimneys, etc.), plants and surrounding buildings, as well as from differences in height of the surrounding terrain (mountains, cliffs, etc.). This is calculated using 3D data which provides information on the above-ground height (roof, treetops, etc.) at each location in the country.
• The pitch and orientation of each square metre of roof space, determined using the same 3D data used to calculate shade.
• Solar radiation measured in the country, corrected to take account of the shade, pitch and orientation of each square metre.

Does the map record personal data?

The solar resource map does not record any personal data. It has been created exclusively from data that is freely accessible via the internet.

Only the approximate position of the buildings you have clicked on the solar resource map is recorded in 500 x 500 metre tiles, for the purposes of tracking website traffic.

Is the solar potential of my roof shared with third parties?

The map data is held by the Prince’s Government.

Under no circumstances will the data from the solar resource map be sold to third parties for commercial solicitation or any other purposes. We recommend that you apply the utmost caution in dealing with any commercial approaches.

How often is the map updated?

The frequency with which the map is updated is different for the different elements that make up the solar resource map.

Calculation of solar potential

This takes a great deal of time to calculate, since it involves calculating the amount of sunshine on an hourly basis over the course of a full year for each square metre of roof space (see How is the solar potential of my roof calculated? ). For this reason, it was calculated once for the entire country when the solar resource map was created, but will not be regularly updated.

Solar potential is often recalculated three years after it is published online as part of work to update the solar resource map website. This recalculation is based on the latest 3D data and the database belonging to the Principality of Monaco’s Urban Planning Office (see How is the solar potential of my roof calculated?  and Why is my building not shown on the solar resource map? ), so that new buildings constructed since the last update can be included.

Calculation of the economic viability of a solar power system

This calculation is dependent on factors that change quickly over time. For example, the grant available for photovoltaic power generation is revised annually to take account of inflation. In addition, the cost of equipment generally tends to decline gradually over time (excluding periods where there are supply shortages).

The parameters used to calculate viability are updated quarterly on the solar resource map so that economic estimates are always an accurate reflection of the current state of the market.

Who set up the solar resource map and why?

The solar resource map was commissioned and funded by the Principality of Monaco. It has been created by Cythelia Energy , a specialist with more than 20 years’ experience in solar power, and a leading authority on solar resource maps in France.

The solar resource map is freely available to everyone who lives in the country, whether individuals, businesses or public authorities. It is first and foremost an awareness tool, designed to promote the growth of renewable energy, especially solar power. It is intended as an outreach tool, conceived as an entry point for citizens, local authorities and businesses keen to learn more about solar power and, where appropriate, as a catalyst for action and the development of new solar power systems.

How reliable are the solar potential calculations?

The accuracy of solar potential calculations is primarily determined by the three factors set out below.

The calculation algorithms

Solar potential is determined using proven algorithms which calculate the sun’s path on an hourly basis over the course of a full year. These algorithms provide a very detailed simulation of all components of the solar spectrum that are used by solar panels (direct and diffuse sunlight, circumsolar radiation, etc.). This produces an estimate that is as accurate as one obtained from the professional solar potential calculation software used in studies to determine the feasibility and sizing of solar power plants.

Roof pitch, orientation and shade

These parameters are determined using 3D data of the country (see How is the solar potential of my roof calculated? ). This data provides information about the above-ground height (roofs, treetops, etc.) of each square metre at any location in the country. Its accuracy has a direct impact on the calculation of shade, pitch and orientation.

Shade is calculated by considering the shadow projected by each square metre within a radius of more than one kilometre around the given location. In addition, shade resulting from differences in height of the surrounding terrain is taken into account within a radius of 50 kilometres. This produces a highly accurate calculation of shade, which incorporates all of the surrounding elements that could hide the sun.

Pitch and orientation are determined locally for each square metre of roof space, then corrected to exclude any outliers (a slope which is too steep, for example).

Meteorological data

This data is drawn from a database that is a global leader in the solar power field. It combines observations on the ground, which provide a high level of accuracy, and detailed time-based sampling, as well as satellite observations, which offer very high resolution and spatial coverage.

How reliable is the information on installation costs and economic viability in the solar resource map?

The economic viability indicators shown on the solar resource map should be considered as orders of magnitude, which seek to give an idea of the costs and benefits of a solar power system. They are intended to reflect current market conditions, by incorporating, for example, changes in the cost of purchasing equipment or the latest mandatory tariffs for purchasing electricity (see How often is the map updated? ).

It should be borne in mind, however, that these are only estimates and cannot offer the level of accuracy that would be provided by a professional survey of your roof carried out onsite. Some important elements, such as the mechanical resistance of the roof structure, cannot be taken into account in the costs shown on the map. It is highly unlikely that the quote that you will receive from an installer will be identical to the number shown on the map. In any event, we suggest that you contact at least three different installers to gain a better sense of the prices charged.

How does the tool simulate photovoltaic self-consumption?

Simulating a self-consumption photovoltaic system implies knowledge of the building’s electricity consumption. When the system is in operation, there are two possible scenarios depending on the time of day and the building’s instantaneous electricity consumption:

• If the building consumes more electricity than the system produces, all of the power generated is consumed directly onsite. The additional electricity required to meet the building’s needs is drawn from the public grid.
• Conversely, if the system produces more electricity than the building consumes, only the power required to meet the building’s needs is consumed onsite. The rest is fed into the public electricity grid (if the surplus is sold) or simply lost (in the case of so-called “total” self-consumption).

The solar resource map compares the amount of solar power generated by the system with the instantaneous consumption of the building, on an hourly basis over the course of a full year, to determine, for any given moment, how much of the electricity generated is directly consumed onsite and how much is sold (or lost). The building’s hourly consumption curve is determined using one of the following methods:

1. If the building is equipped with a smart meter (Nexio), Nexiopro customers can retrieve the consumption curve at hourly intervals from the SMEG website. The file obtained can then be uploaded into the solar resource map tool. Individuals can request it directly from SMEG.
2. If the building is a residential one and its total annual consumption is known, this can be input into the solar resource map tool. It will then be used to create an hourly consumption curve representing a household. This option is only available for residential buildings, since the shape of the consumption curve is highly dependent on the building’s use (industrial, service sector, etc.).
3. If the building is a residential one and its electricity consumption is not known, a few simple questions can be answered. These will enable the solar resource map tool to estimate the residential building’s annual electricity consumption. For example, the number of floors allows the floor area to be calculated. This will be used to estimate consumption associated with electric heating, if any. Similarly, the number of inhabitants allows estimates to be made of specific consumption (refrigerator, hob, lightbulbs, IT equipment, etc.) and consumption for electric water heating, if any. The annual consumption is then used to create a consumption curve representing a household (see above). Like the second option, this option is only available for residential buildings.

Once the annual savings on electricity consumption have been calculated, the solar resource map converts these into euros, taking account of the average cost of electricity smoothed out over the next 25 years. This is obtained by assuming a 3% increase in the cost of electricity each year.

Revenue from the sale of surplus electricity is calculated based on a tariff of €0.04 per KWh injected. It should be noted that the solar resource map tool routinely calculates options both with and without the sale of surplus electricity, but only shows the option which is most economically advantageous.

How does the tool simulate the output and viability of a solar thermal system?

Solar thermal systems are always sized to meet the needs of the building in order to minimise overproduction. Unlike with photovoltaic systems, excess output from a thermal system is very difficult to sell or gain benefit from.

The first stage in simulating a thermal system involves estimating the building’s annual hot water consumption. This can only be reliably estimated for residential buildings, since a company’s consumption is highly dependent on sector (industrial, commercial, etc.). Conversely, the hot water requirements of a residential building are, in practice, dependent only on the number of occupants. The solar resource map assumes average consumption of 30 litres of hot water per person per day.

Once annual hot water consumption has been calculated, the solar resource map uses a leading professional approach, known as SOLO, to estimate the share of hot water that could be provided by the solar power system. These hot water savings are then converted into euros. It should be noted that the solar resource map currently only calculates savings for buildings which are equipped with electric water heating, as it is in these cases that the cost of the solar power system will be recouped most quickly.

Who should I contact for help in considering and installing a solar power system?

Before installing a solar power system, we suggest that you contact the Mission for Energy Transition, which can offer guidance and answer any questions you may have. It will assess the location of your building and advise you on the procedures to follow, and can answer any questions you may have about renewable energy and energy-efficiency upgrades for buildings.

In addition, we recommend that you always contact at least three different installers to gain a better sense of the prices charged.

How are the grants introduced by the State of Monaco taken into account when estimating economic viability?

For further information, please refer to the Mon Service Public website.