Centuries ago, human started using resources to create energy with coal and petroleum (Manish and Banerjee 2008). But, over the decades the resources started consuming up at a very deadly rate, leading to almost exhaustion of all the resources present globally (Koumi Ngoh et al. 2014; Delpisheh et al. 2021). As the rate of generation is far less as compared to the rate of their usage, hence need of switching to non-conventional sources of energy i.e. renewable sources of energy is the hot topic these days. Renewable energy sources include wind, solar, tidal, and other forms of energy. Amongst all of them, there is an efficient source of energy which is green hydrogen (Barco-Burgos et al. 2020; Haider et al. 2021).
Hydrogen has the potential to substitute non–renewable sources of energy in various sectors like transportation, commercial, industrial, residential, etc (Mutlu et al. 2020; Gutiérrez-Martín et al. 2021). The thermo-physical properties of hydrogen have been represented in Table 1 (Nasser et al. 2022). Projections suggest that the hydrogen market will reach a substantial value of 2.5 trillion dollars by 2050 (Liu et al. 2008; Touili et al. 2020). Due to its versatility, eco-friendliness, and high energy density, hydrogen has emerged as a promising contender to replace fossil fuels as the primary global energy source. It can be produced in so many ways like electrolysis, steam reforming, gasification, etc (Jia et al. 2016; de Fatima Palhares et al. 2018). One of the methods is electrolysis in which we use electricity to produce hydrogen and oxygen from water (Singh and Rathore 2016; Kovendhan et al. 2019). Different types of hydrogen are shown in Fig. 1.
Table 1
Thermo-physical properties of hydrogen
| Property | Value |
| Density at STP ( kg/m3) | 0.084 |
| LHV ( kJ/g) | 120 |
| Melting point (K) | 14.01 |
| Normal boiling point (K) | 20.3 |
| Critical temperature (K) | 32.97 |
| Critical pressure (bar) | 12.9 |
| Flammability limits in the air (vol%) | 4.1–75 |
| Auto ignition temperature (K) | 858 |
| Adiabatic flame temperature (K) | 2400 |
| Flame speed ( m/s) | 2.75 |
Now, if the electricity used is generated by renewable sources, then the hydrogen produced can be termed green hydrogen (Elbahjaoui and El Qarnia 2019; Hosseini and Wahid 2020). Green hydrogen can be produced through solar energy or any other renewable energy sources, such as wind power, and later the use of green hydrogen can play as a source of clean energy (Mahidhara et al. 2019; Perera 2019; Sezer et al. 2019). The versatility of hydrogen is a key advantage, making it applicable in various fields such as transportation, heating, power generation, and fuel cells, where it can be readily converted into mechanical energy. Transportation, in particular, benefits from hydrogen due to its extended range and rapid refueling capabilities (Brauns and Turek 2020; Chandrashekara 2020; Razi and Dincer 2020).
Most of the studies on electrolysis have focussed alkaline anion exchange process. Some authors examined the potential of biohydrogen production processes, such as dark-fermentation, photo-fermentation, two-stage processes, and biocatalyzed electrolysis, as renewable energy carriers (Manish and Banerjee 2008; Al-Shanini et al. 2014). Some researchers have employed a hybrid energy system, consisting of a combination of a wind turbine, solar PV, an AFC, a stirling engine, and an electrolyzer. This integrated system serves the purpose of generating both electricity and hydrogen fuel (Pathak et al. 2020; Burton et al. 2021; Wang et al. 2021). Photo fermentation technology has also been used for biohydrogen production. But the low light conversion efficiency and the result of purple nonsulfur bacteria (PNSB) make necessary biotechnological approaches to embellish this process. A critical review has been done by researchers to focus on improving biohydrogen production, which is critical for its technical-scale implementation. The limitations and restraints associated with bioreactor operation are tried, and discrete approaches for an improved biohydrogen are explored. These approaches include substrate pre-situations, inhibitors expulsion, bioaugmentation, immobilization, effluent reusing, buffering capacity maintenance, and outgrowth utilization (Tiang et al. 2020; Banu J et al. 2021).
All conventional fuel reserves have their limitations. Similarly, the supply of green hydrogen is still limited and the reasons are safety in transportation, the high cost of production and lack of infrastructure for its storage, distribution and use. Also, the sources of production of green hydrogen are renewable sources which again are quite expensive but maybe in the future we may reach and find out some economical way of extracting green hydrogen. So, our efforts are still there to extract green hydrogen and its storage with proper safety and its use to minimise the pollution and save our earth. In this study, we will try to focus on the production of green hydrogen by solar energy with the photovoltaic behaviour of the solar photovoltaic system.