Solar PV Fundamentals

There are two main ways in which solar panels can be installed at homes or in buildings. The first one is known as “addition”. This method entails setting up solar panels at an already built home or building. Many urban areas constructed in the past did not have solar PV in mind as a way to power homes. Old buildings made by traditional real estate developers rarely thought of installing solar PV to power them or as a way to produce heating. Before adding solar PV to an existing building you might need to get municipality permits and different types of community approvals. Another drawback is that you might have limited space to install or retrofit PV panels into the already existing structure. On other hand, this option can be cheaper than the integration method. 

In the integration method, architects and engineers integrate the solar potential before starting the home or building construction. This is also known as building-integrated photovoltaics (BIV). A great example is the Library from Pompeu Fabra University in Barcelona. The Library, located in the city of Mataró, produces its own electricity and thermal energy to power appliances and heat the 603 m2 building. The library’s walls are formed by multifunctional polycrystalline cells placed in specific patterns such that they allow for some light to come into the building. The entire system (rooftop and facade together) has a peak power production of 53 kWp. 

This was the first European project with these unique architectural and engineering characteristics and was made possible due to the EU Joule II program support. One of the greatest achievements from this project was the ability to combine photovoltaic, polycrystalline, monocrystalline and amorphous silicon cells in the same building. Not only this provided an aesthetically pleasant result, but it also allowed it to be functional enough (allowing light in for example) for people to spend time inside the building with ease. 

I will be explaining each component in more detail. To start with, I’d like to showcase the power generation capabilities of each component from the building:

Pompeu’s Library main facade is 37.5 meters wide to 6 meters tall with a surface area of 225 m2. Therein are 108 semi-transparent PV panels. Cells inside each panel have a 1.4 cm row horizontal separation. To create heating in the area, there is a 15 cm glass pane behind the solar panels that creates an air chamber. 

If we look at the rooftop system, there are four rows of tilted skylight with each row containing up 30 opaque modules and 6 semitransparent modules in the middle tilted at 37°. These generate electricity through both the opaque and semitransparent solar panels while allowing natural lightning to pass through from the north. The three rows closest to the south use monocrystalline cells (highest solar to energy efficiency), the fourth uses polycrystalline cells and the central area uses semi-transparent a-Si components. 

Regarding power generation capabilities, the peak power generated in the facade is 20 kWp. The monocrystalline area of the rooftop is about 23.4 kWp whilst the polycrystalline section can generate up to 6.9 kWp. Lastly, the amorphous silicon area generates only 2.4 kWp. 

In terms of thermal management, the building has a system of ducts with fans that captures warm air generated when the solar panels are heated up. This hot air is moved towards the buildings’ regular gas heating system leading to energy savings of up to 30%. In summer, when the air is hot, the air evacuation system lets the air out and cools the building down with less energy consumption than otherwise. 

Is building-integrated photovoltaics complex and challenging? Absolutely! This requires specialized skills and technologies to make these types of constructions available. However, energy savings and autonomy are great long-term benefits obtained from these projects.

Another way to integrate solar energy into the urban-rural landscape is through ground installations. Some countries have the potential to even co-locate solar and agriculture on the same land. If well planned, this can create enormous benefits to the solar as well as agricultural industries. Both industries are space intensive in the sense that they require substantial land in order to meet its production targets. Co-location of agriculture and solar is known as agrivoltaics. Crops, livestock and even pollinator habitats can coexist under the solar panels. There are more than 300 agrivoltaic projects just in the U.S. with over 2.8 GW capacity (as of 2023, U.S. total solar capacity reported was 219.8 GW). While this is still a small number, potential is huge as solar energy could provide up to 1 terawatt of electricity-generating capacity to the grid by 2035. According to the U.S. Department of Energy, this could require more than 23,000 km2–larger than the size of El Salvador–in land. The same land that is useful for solar energy can typically be used by agriculture to produce food (except for deserts or very dry areas with little rainfall). Another important benefit is that multiple revenue streams can be generated from the same area, thereby reducing land use competition and stimulating new business models and partnerships across industries.

A real commercial example of agrivoltaics is BayWa r.e. Corporation in The Netherlands. The project focuses on wheat, potato, celery, blueberries, red currants, raspberries, strawberries, and blackberries. According to RatedPower, results are positive. On hot days, crops are less exposed to heat stress since solar PV coverage leads to relatively lower temperatures by about 2 to 5 degrees lower than without solar PV.  In addition, with PV solar, crops retained heat better at night and did not need the plastic coverage that is typically used in agriculture. 

Solar power can be on-grid or off-grid. On-grid, as the name suggests, is connected to the grid. It generates electricity which may or may not be stored in an external battery or sent to the grid. A famous on-grid project was the California Valley Solar Ranch which became online in October 2013. It is the first 250 MW solar generation project with T-0 single axis trackers combined with wireless tracker monitoring and control system (TMAC). Single axis trackers with a TMAC system in simple words mean that they follow the sun’s movement to achieve maximum sunlight utilization. This can lead to power output improvements of approximately 25%, compared to traditional fixed installations. 

The project generated 350 construction jobs and supports 11 permanent jobs. Moreover, sources indicate that tax revenues amount to USD 10 million and an overall injection of USD 315 million in the local economy of San Luis Obispo. The overall energy production per year from the project prospect was 650 GWh per year (that would be less than 1% of total solar energy produced in the U.S. in 2023, which is reported to be 164,500 GWh). Emissions reductions were calculated to be 370,000 metric tons of CO2 annually (to put that in perspective, 369.2 million metric tons of CO2 were generated in 2020 just for California). The overall cost (total amount loaned) was $1.2 billion. 

Another example is The Longyangxia Dam Solar Park, which is located high on the Tibetan plateau in China’s western province of Qinghai. The park is 27 square kilometers of what was previously a barren, wind-swept cattle ranch. The installation consists of nearly 4 million deep blue solar panels that stretch toward snow-capped mountains on the horizon.

It cost approximately 6 billion yuan (or about $822 million dollars as of January 2nd 2025 exchange rate). If you look at the costs, this is cheaper than the U.S. California Valley Solar Ranch. Construction began in 2013, and the facility has been expanding almost continuously since then. The park now has the capacity to generate 850 megawatts (MW) of power, which is enough to supply electricity to approximately 200,000 households.

The project is managed by Huanghe Hydropower Development, a state-run company, under the leadership of Chairman Xie Xiaoping. Some challenges include being able to offset transmission and distribution losses since the park is located far away from major population centers.

There are many small-scale off-grid solar installations that have enabled homeowners to become independent from the grid and live in far-off remote areas. A compelling example comes from Low, Quebec, Canada, where a couple built their dream home over a mile down a private road. When faced with grid connection costs exceeding $100,000 just for power poles, they opted for an off-grid solar solution that demonstrates the real-world possibilities of independent power generation. Their system combines 24 solar panels delivering 5,820W of total capacity, with a robust battery storage system providing 25 kWh of power storage through eight Deka deep-cycle batteries. To ensure reliable year-round operation in harsh Canadian winters, they made several innovative adaptations, including setting their solar panels at a steeper 65-degree angle rather than the conventional 45 degrees to improve snow shedding and winter performance. The system successfully powers their home’s essential needs, including refrigeration, heating, ventilation, and electronics, consuming approximately 1,500 kWh annually (about 4 kWh per day). While the cost of power generation is higher than grid electricity ($1/kWh compared to 10¢/kWh), the system demonstrates how off-grid living can be achieved through careful energy planning and efficient design. However, it’s important to note that the home still relies on propane and wood for heating in winter months, highlighting that complete energy independence often requires a hybrid approach to meet all household needs. 

What examples do you have to share?