A Qualitative Analysis of Factors Leading to the Adoption of Residential Photovoltaics

Abstract

Although previous quantitative studies have examined various elements involved in the adoption of residential photovoltaic systems, there has been weaker emphasis on qualitative research despite its ability to understand the complexities behind adoption decisions. This article analyzes data from in-depth interviews with adopters and identifies emerging themes about the factors leading householders to adopt residential photovoltaic systems. Thematic analysis identified five key themes related to the economic, environmental, social and technological motives and barriers to adopting residential photovoltaics. Adopters’ main motive was to acquire an additional regular income, which, inter alia, would enable them to cover anticipated expenses such as costs linked to having children at university. Many adopters also combined the adoption with life events such as house renovations. The adoption of photovoltaics was also seen as providing a safe way to invest savings. Moreover, most adopters identified themselves as technology enthusiasts indicating the positive effect of technophilia on residential photovoltaic adoption. Despite having installed photovoltaics, participants recognized that adoption can be inhibited by high capital cost, investment taxation and limited grid capacity. The similarities and variety in the decision-making patterns identified in this study can be used to develop or improve strategies aiming at increasing residential photovoltaic adoption.

1. Introduction

In contrast to the fossil fuel market, which is accessible to only a few actors, the renewable energy market is open to different groups who wish to participate in electricity production and obtain economic gains. Specifically, householders can participate in and benefit from feed-in-tariff and net-metering programs, while residents in the vicinity of renewable energy projects can take advantage of revenue-sharing dividends, equity co-investments and community projects. A prominent advantage of these programs is that they can be accessed even with limited capital. It should be noted, however, that the availability and form of such programs vary greatly by country due to financial laws and different energy contexts [1]. In terms of householders, the adoption of residential photovoltaic systems can not only improve energy security and affordability, but also provide significant economic benefits [2,3,4,5]. As the cost of residential photovoltaic systems continues to decrease and grid parity is attained, residential photovoltaics have evolved into a feasible and favored technology in many communities. For these reasons, residential photovoltaics are often viewed as a feasible solution to help households improve their energy consumption, while achieving decentralization and carbon emissions reduction targets [6,7].

Another important point to consider is that solar development exhibits substantial disparities across countries and even among regions within the same country, while, at the same time, the geographical pattern of adoption is constantly changing. In other words, solar development is remarkably diverse even in contexts exhibiting similar conditions. Regardless of the considerable differentiation, the installed capacity of solar energy has been following an increasing trend in most countries [8] and, as an example, it has been the fastest growing energy source in the European Union (EU). During the recent gas crisis, a “solar boom” was experienced and, indicatively, solar capacity rose from 164.19 GW in 2021 to 338 GW in 2024. However, as the urgency to protect from the energy crisis is fading, the solar sector is now faced with an alarming deployment slowdown with growth having fallen from 53% in 2023 to only 4% in 2024 raising concerns about the feasibility of 2030 goals [9].

Realizing the potential of citizen participation, more and more countries put in place incentives and policies for householders to install photovoltaic systems. Among these are net-metering programs, tax credits, tax easements and sponsored solar financing programs, as well as direct cash incentives [10,11]. At the same time, the competitiveness of photovoltaic systems has increased due to technology maturity and lower production costs. These factors bring forward the need to understand diffusion patterns, that is, what motivates people to adopt them [12,13]. Having a precise idea on the different factors that influence adoption can not only guide the design of policy instruments and marketing strategies, but also help predict future diffusion thereby facilitating crucial decisions on the direction of future energy policy [13]. Diffusion research on residential photovoltaics has been evolving since the 1980s and so far researchers have focused on social, technical, economic and policy aspects. Seen from a broader perspective, the way householders perceive residential photovoltaics determines adoption decisions [14]. To proceed to adoption, therefore, householders need to perceive solar systems as ones that provide a relative advantage [15]. This should not mean, however, that adoption decisions are simple and that the provision of benefits would be sufficient; on the contrary, research has shown that households act as heterogeneous entities and, consequently, adoption intentions exhibit a high degree of variation [16].

Previous research has explored the elements of technology adoption concluding that social variables are critical to householders’ decision to adopt solar systems [17,18,19]. This may involve the level to which adopters are affected by their peers, mostly neighbors and acquaintances that have already installed photovoltaics at their residence [18,19]. It is through discussions with them that potential adopters have the opportunity to learn more about the systems and overcome concerns about the feasibility of the technology [20,21,22]. In addition, many adopters recognize in them the role of setting an example in their community and demonstrating the environmental benefits of renewable energy [21,22]. In other words, adopters may use their highly visible solar systems to inform their community about their pro-environmental values [23,24]. Social motives such as these are so important that they often compete with other motives like saving money, attaining comfort and freedom [25]. This emphasizes the need to re-evaluate the effect of social groups in relation to the factors defining adoption decisions. Social variables may also be useful in explaining individuals’ decisions to adopt certain behaviors and change their lifestyle [26]. Other social variables that have been included in the relevant research include gender, political values and ethnicity [1,4,7].

The diffusion theory in the context of residential photovoltaics emphasizes the role of peers (adopters’ neighbors and friends) in adoption decisions indicating that peer effects occur mostly via word of mouth rather than as passive observations [18,27,28]. Through word of mouth, potential adopters have the opportunity to discuss various aspects of photovoltaics with their peers and may then experience less uncertainty and eventually decide to adopt them [13]. In other words, seeing members of the community having installed photovoltaics on their rooftops increases interest and has a positive influence [15]. At the same time, important adoption motives include environmental concerns, economic gains and technophilia [20].

Having highlighted the key findings regarding the adoption factors of residential photovoltaics, the attention now turns to the policy framework. In the European Union, solar energy plays a key role in the union’s effort to transition to a clean energy system as stated in the European Green Deal and the recently adopted REPowerEU plan [29]. Over the last three years, the European Union has managed to double its solar capacity and most member states will possibly surpass their 2030 solar targets [30]. Solar energy is also considered strategic due to its contribution to reducing EU’s dependence on fossil fuel imports and its ability to protect households from volatile energy prices [31]. Acknowledging the need to accelerate the deployment of solar energy, the EU has launched its solar energy strategy which seeks to achieve over 320 GW of solar photovoltaics by 2025 and 600 GW by 2030. In the context of the strategy, three initiatives have been launched. Among these, the European Solar Rooftops Initiative aims to leverage the vastly unexploited potential of rooftops for the production of clean energy and focuses on making new buildings solar-ready. In addition, the Energy Performance of Buildings Directive has the potential to power the equivalent of 56 million houses with solar energy. This may become feasible through the EU Rooftop Standard which is included in the directive and promotes the installation of up to 200 GW of additional rooftop solar capacity between 2026 and 2030.

Even though the European Union has experienced a remarkable increase in installed solar capacity, this success can be largely ascribed to events such as stark energy price increases, concerns over energy supply outages and efforts to reduce dependence on Russian fuels [32]. For this reason, the increase in solar installed capacities could be over soon and, consequently, EU’s solar objectives may not be met despite the remarkable progress recorded over the last years. To ensure that the progress will not cease, it is important to turn the policy attention towards householders acknowledging their potential role as capital providers and supporters of solar energy targets [33,34]. In other words, it is necessary to understand what motivates householders to adopt solar systems at their house in order to devise novel measures that will ensure the continuous adoption of residential solar energy. What is more, the research interest should be on residential photovoltaics due to their advantages over other renewables; they do not require the construction of public infrastructure nor are they installed on valuable land as the facilities of wind energy and farmland photovoltaics. Another advantage is that residential photovoltaics are socially identified as “clean” or “green” energy and have become accessible to householders due to cost decreases and technology maturity. For these reasons, it would not be far-fetched to state that solar energy on rooftops may be the public’s most preferred renewable type and a type of renewable that holds great potential in terms of decarbonizing the energy mix.

Against this background, the aim of this paper is to investigate the factors that lead householders to adopt residential photovoltaic systems. Specific objectives are to capture the motives and barriers involved in adoption decisions. Utilizing a sample of adopters and through the lens of qualitative research, the study provides a nuanced picture on the factors that lead householders to adopt photovoltaics at their residence. This article draws on interviews carried out with adopters in Greece and, following the strategies of researchers who have previously included economic, environmental, social and technological drivers, we also consider their influence on adoption decisions.

2. Materials and Methods

2.1. Research Approach

The views on the economic, environmental, social and technological motives, as well as barriers to PV adoption of Greek adopters were examined with in-depth interviews with householders that installed photovoltaic systems at their house. In-depth interviews’ ability to provide access to respondents’ viewpoints and beliefs was considered appropriate for adopters because the intention was to attain a thorough understanding of the factors underlying their decision to proceed to investments.

Interviews have proliferated, diversified and developed from a research strategy to an independent research method, which is used in a wide range of disciplines [35]. In-depth interviews have been described as a qualitative research method which entails the performance of intensive individual interviews with a small number of people with the purpose of exploring their perspectives on a specific idea, topic or situation [36]. As interviews are suitable for addressing more complicated research questions such as understanding whether a service is performing well or whether it can be enhanced based on the recipients’ perspective, they were considered suitable for understanding the complexities involved in the decision of adopters to proceed to the installation of photovoltaic systems at their house [37].

In-depth interviews have also the ability to facilitate interviewees’ opinions in their own words and can be very effective when interviewees have a personal interest in the examined topic [36,38]. Another advantage is that the interviewer is provided with access to interviewees’ thoughts, motives, experiences, interpretations and opinions on the topic under scrutiny [36,39]. This is feasible because interviewers can probe interviewees’ statements by asking more questions to attain a more profound understanding and also focus the interview on the most intriguing themes in a discreet manner [39].

Unlike open interviews, in-depth interviews are semi-structured and employ an interview guide which draws on existing objective knowledge about a matter and includes open-ended questions with follow-up probe questions [37]. The design of the guide and the content of the questions for this study took into account previous literature on the factors affecting adoption decisions [40,41,42,43,44,45,46,47,48]. More analytically, the interview guide first included a few closed-ended items collecting demographics and then continued with open-ended questions that explored the reasons that participants had adopted photovoltaics, the barriers that they encountered, the measures that could be taken to attract investments, satisfaction with stakeholders involved in investments, the information sources that were used to obtain information on the systems and information needs. Once the interview guide with the questions was designed, the next stage was to pilot test the interview guide in order to evaluate its accuracy, coherence and efficacy [49]. Specifically, the pilot interviews helped the researchers understand whether questions had been worded in a way that was easy to comprehend as well as whether the questions could enable interviewees to talk about all the significant areas. In this research, five pilot interviews with adopters from different areas were conducted and, through these pilot interviews, meaningful comments were yielded that improved the clarity of the interview guide; in particular, the formulation of four questions was simplified according to interviewees’ recommendations. In accordance with the existing legislation, the present study was approved by the Research Ethics Committee of the Democritus University of Thrace (Decision No. 3/09–12-2019).

2.2. Participant Recruitment

According to the principles of in-depth interviews, interviews can be recorded on paper or, alternatively, an electronic data capture application can be used. It is also important to consider the way that the interviews will be held. Although there has been an increasing preference for interviews conducted via telephone and video, in-person interview is generally the most preferred modality due to its reliability and, for this reason, it was the one used in this study [37]. Regarding recruitment, while, in quantitative research, researchers strive for probability sampling methods and large sample sizes, the approach in in-depth interviews should be different [37]. In particular, in-depth interviews employ non-probability sampling because the aim is not to achieve generalizability. The most frequently used sampling type in in-depth interviews is purposive sampling in which participants are selected based on whether they meet specific criteria. The sample size is considered adequate when there is thematic saturation; that is, reaching the point where the data from interviews produce no more new codes or themes. In this study, thematic saturation was reached in the fifteenth interview, but five more interviews were performed ensuring that no new themes and patterns would emerge.

All participants had to be adopters of residential photovoltaic systems. To recruit participants, the researchers contacted companies involved in residential solar panel installation and asked them to contact their clients and inform them about the study. Then, the companies prepared lists with the clients who were interested in participating. To recruit participants and to avoid selection bias, researchers used a draw to randomly select 20 clients from the lists. In consultation with participants, interviews were scheduled and conducted at quiet places (such as cafes and libraries). All participants were asked and agreed with the recording of interviews for transcription purposes. Each interview lasted between 28 and 50 min. All interviews were performed in the Greek language and were also transcribed and analyzed in Greek. The themes, codes and participants’ excerpts were translated in English when preparing this paper. Before the analysis, all personal identifiers were removed from transcripts and participants were referred to as “Participant 1”, “Participant 2” and so on. Excerpts reported in this paper were subject to no or minor revisions and, in the latter case, revisions were made only to ensure that the excerpts would be understood by the readers. Moreover, minor revisions were made only if it was considered that the revisions would not have the slightest effect on the meaning of the excerpts.

2.3. Data Analysis

The data were transcribed and, to analyze the transcripts, the thematic analysis protocol proposed by Braun and Clarke [50] was employed. This type of analysis serves to identify, analyze and report patterns (i.e., themes) that occur within the transcribed data. In other words, thematic analysis organizes and describes the data in great detail while interpreting different aspects of the topic under study [50]. Themes are, therefore, pursued in the analysis because they capture something significant which is closely related to the research objectives. Themes may also represent a degree of patterned response or meaning. Although themes could occur in a number of instances across data, a high frequency does not always suggest that the theme is crucial. For this reason, the judgment of the researcher is essential to decide what a theme is and this depends on whether it captures something significant in relation to the research [50].

According to the protocol of Braun and Clarke [50], the analysis has to follow six phases. In the first phase, the researcher has to become familiar with the data and it is in this phase that the data are transcribed, read and re-read, and the initial idea is noted down. Familiarization with data also includes the comparison of notes taken during the interviews with the transcripts in order to ensure similarity and to confirm that no significant information is missing (Phase 1). In the second phase, initial codes are generated and this is achieved by coding interesting characteristics in a systematic way and collating data related to every code. Then, in the third phase, themes are sought through the collection of codes into potential themes. In the fourth phase, the themes are reviewed by checking whether the identified themes work based on the coded excerpts. In this way, a kind of thematic “map” of the entire analysis is produced. In the fifth phase, the themes are defined and named and, in this way, the specifics of all themes are refined, while clear definitions and names for the themes are produced. Finally, the report is produced providing a final opportunity for analysis through the choice of lively and compelling excerpts, with the whole analysis being related back to the research question and literature. The analysis, therefore, involved a continuous moving back and forward between the entire data set, as well as the coded extracts, while many repeated review rounds took place before producing the report of results.

3. Results

3.1. Profile of Study Participants

The sociodemographic characteristics of participants are presented in

Table 1. Demographic and basic characteristics of study participants.

		N
Gender	Male	11
	Female	9
Age	31–40 years	4
	41–50 years	11
	51–60 years	5
Education level	Middle school	3
	High school	2
	Technical school	1
	University	10
	Postgraduate/Doctoral	4
Family status	Married	12
	Unmarried	2
	Divorced	2
	Widowed	4
Children	Yes	18
	No	2
Year of investment	2006	2
	2011	5
	2012	6
	2013	3
	2014	2
	2015	2
Received loan to adopt PV	Yes	6
	No	14
House ownership	Yes	20
Received loan to adopt PV	Yes	6
	No	14
Received subsidy to adopt PV	No	20

and it can be seen that male participants slightly outnumbered their female counterparts, while most participants were aged over 41 years. In terms of their education level, participants presented a high level of education and most were university graduates while two participants had attended postgraduate and doctoral studies. As for their marital status, the majority were married and had children, while a substantial number of interviewees reported having children. Most had adopted photovoltaics in 2011 and 2012 and were the owners of the property where photovoltaics had been installed. Six interviewees reported having received a loan to invest.

3.2. Themes with Representative Excerpts

Thematic analysis of interview transcripts elicited five themes and

Table 2. Themes, sub-themes and codes.

Themes	Sub-Themes	Codes
Economic drivers for investing in residential solar photovoltaics	The acquisition of an additional regular income	Acquisition of “passive” income Additional income to cover various household expenses Economic security
	Intention to make an investment per se	Invest savings Option with high return
	Combining the adoption with major life events	House building or renovation Widowhood Studies of children Unemployment
	Desire to become independent from power companies	Independence Autonomy
	Reduction in electricity costs	Economic difficulties Economic crisis
The role of the environment in the adoption decision	Strong effect of environmental protection on adoption decision	“Good deed” towards the environment Save the planet for our children
	No effect of environmental protection on adoption decision	RES is a huge “business” benefitting only big companies No consideration of environmental protection
	Plenty of sun in the study area	Greece as “rich” in sun Abundant sunlight should be leveraged
The social context of PV adoption	Affected by “others”	Saw photovoltaics on other houses Talked to friends and acquaintances who had PV systems
	Not affected by others	Participant was the first to adopt PV in their local area/neighborhood First to adopt and then others followed
The effect of technology on the adoption decision	Technology as a positive factor	In favor of new technology Perceived association of PV technology with science Trust in new technology
	Skepticism about the new technology of photovoltaics	Concerns Insecurity Feeling of risk
Barriers to the adoption of residential photovoltaics	High cost of investment	High capital required Economic difficulties People lacking the means to invest
	Lack of trust	Diminished trust due to unilateral electricity price reduction
	Insufficient policy support	Inadequate incentives No subsidies Existing policy support is offered only to large RES investors
	Taxation	High taxation Unexpected taxes on residential systems
	Financial risk	Uncertainty about the return of investment
	Limited grid capacity	Grid congestion
	Fear and misinformation	Insufficient information availability Concerns due to misinformation
	Limited number of licenses	Unavailability of licenses for small-scale RES systems

summarizes the identified themes along with their sub-themes and codes. The identified and labeled themes are “Economic drivers for investing in residential solar photovoltaics”, “The role of the environment in the adoption decision”, “The social context of PV adoption”, “The effect of technology on the adoption decision” and “Barriers to the adoption of residential photovoltaics”.

• Theme 1: Economic drivers for investing in residential solar photovoltaics.

Sub-themes explicitly mentioned when discussing the economic drivers of participants’ decision to adopt residential photovoltaic systems involved: the acquisition of an additional income, the desire to make an investment per se, the intentional combination of the investment with major life events and the intention to be independent from electricity companies, as well as the reduction in electricity costs.

Acquiring an additional regular income was cited as a very important reason for adopting residential photovoltaics by nine participants and it may be stated that this was the strongest adoption motive. Moreover, the fact that this income would be passive rendered the investment highly attractive to some interviewees. Even those who required a loan to invest reported having perceived that after loan repayment they would enjoy a substantial additional income with which they would be able to cover various household expenses. As can be derived from the following two quotes, participants had a very clear view that the adoption of residential photovoltaics could be the means to acquire a “stable extra income” and, at the same time, to attain “economic security”:

I knew, however, that if I did it (adopted), I would get some money every month. It turns out that every four months I do have an income which I know I will get no matter what happens. And I also know in advance how to plan my affairs.

(Participant 1)

As soon as I would repay the loan (which the participant took in order to install photovoltaics at residence), there would be something with which I could increase my income. I did not adopt them in order to become rich or something, but only to have an extra income.

(Participant 3)

The second most cited economic driver was the desire to make a “good investment” with a high return. This economic driver was cited by seven participants. It seems that, for participants who desired to make an investment and had savings, investing in residential photovoltaics seemed to be the best available investment option:

For us (the participant and her husband), it was the best investment. We had some savings at the bank. If we left that money standing there, what would we get? If, however, we invested then we would receive some money every month.

(Participant 1)

The careful estimation of specific investment criteria led some participants to realize that this investment would have a good return:

Examining the whole investment in terms of the system that my money could buy and the price with which at that time the Public Power Corporation would buy my electricity, it was clear that this was a very good investment. That is, after three and a half to four years, you had the money you invested which meant that for the following 20 years you would have sheer profit.

(Participant 11)

Yet, few adopters were not so meticulous in examining criteria:

Well, I just wanted to be able to say that, yes, I have made an investment in my life. I saw it explicitly as an opportunity to make an investment.

(Participant 10)

Some interviewees decided to adopt photovoltaics due to certain life events that led them to consider the adoption as a way to ensure an additional income for the following years. Major life events were thus distinctly associated with participants’ adoption decision. Such life events involved widowhood, having children at university, unemployment and house renovation. In relation to widowhood, two female participants decided to invest after the death of their husbands and the subsequent loss of their husbands’ economic contribution to the household.

I was looking for a way to increase my income once my husband died. I was quite young when I became a widow and it was important for me to secure an extra income.

(Participant 3)

There were also participants who reported that they saw the investment as a way to cover the expenses of their children’s university studies. That is, these participants wanted to use the additional income from selling the electricity to the grid, in order to afford the living expenses of their children that attended university in different cities. The following response exemplifies this:

My decision was affected by my desire to help my children complete their university studies. As they were studying in other cities, the expenses were huge and I had to find a way to get an additional income to cover these expenses.

(Participant 3)

Interestingly, unemployment was cited as an event that prompted one participant to decide to adopt photovoltaics. As the participant explains:

I was unemployed at that time. I had no job and we (the participant and her husband) required something extra to make ends meet in the long run.

(Participant 8)

Renovating or building a residence were life events that some participants tried to make combine with the adoption. In particular, two participants cited renovation as an optimal opportunity to upgrade both the energy performance of their residence and the heating system. The way that these events affected their decision was explained in detail by two participants:

I thought that since we are building our house in these economically difficult times, it would be advantageous to install photovoltaics. It was a step forward.

(Participant 2)

Back then we were renovating our house. But our house did not have a solid roof. The roof had to be repaired and reinforced with the addition of new materials. So, we thought that since we need to change the roof, it is a good opportunity to install the panels. For the next twenty years, the roof would be solid and would not require removal or repair. Therefore, installing them (photovoltaics) now would be safe.

(Participant 13)

Being able to cover or reduce the electricity costs of their household emerged as another significant reason for adopting residential photovoltaic systems. The following response provides a thorough explanation of how some participants perceived the investment in relation to electricity costs:

We were already experiencing the economic crisis and this exercised a lot of pressure on us. We had some savings and we thought that if we invested it, we could reduce a little the electricity costs that lie ahead. We really wanted to be ahead of the economic difficulties that would emerge.

(Participant 6)

• Theme 2: The role of environmental values in the adoption decision

The effect of the environment on participants’ decision to adopt photovoltaics was also discussed in the in-depth interviews. Over half of participants (n = 12) reported valuing the pro-environmental aspect of pro-environmental systems and thought that by adopting them they would contribute to environmental protection. The following quotes are illustrative of the effect of environmental values on adopters’ decision:

Unfortunately, we (humans) are still using energy sources that pollute the environment. If we continue to do this, nature will avenge us.

(Participant 2)

For me, it (environmental protection) was the most important reason. The investment was a good deed towards the environment. We must also think about our children who will live on earth after we are gone.

(Participant 5)

Some of the interviewees (n = 6), however, admitted that their decision was affected exclusively by the economic gains that the investment could yield rather than the contribution to environmental protection. When discussing further the role of the environment in their decision, some highly interesting views were expressed. In particular, there were participants who did not believe that renewable systems such as photovoltaics are able to contribute to environmental protection, while others thought that photovoltaics are somewhat better than other renewable types, such as wind energy, which was described as environmentally harmful. The following quotes illustrate these points:

For me, it was only the economic aspect of the investment that mattered.

(Participant 11)

The environment did not affect my decision not even in the least. In terms of their environmental impact, however, photovoltaics must be somewhat better than other renewable types, such as wind turbines, which are an absolute disaster for the environment.

(Participant 4)

No, I do not believe those things. Renewable energy is a huge business that benefits only large companies. We, adopters, should act only in our own interest.

(Participant 6)

Some participants also reported that environmental protection was a secondary motive or that it was perceived as an equally important investment motive.

Although at first I was thinking only about the economic profit, then I started to appreciate the fact that the investment was pro-environmental.

(Participant 11)

The pro-environmental aspect was equally important for me.

(Participant 12)

When discussing the role of the environment in their decision, another sub-theme that emerged had to do with the remarkable renewable potential of Greece. That is, a considerable number of interviewees perceived that more houses should install solar systems in order to leverage the extensive hours of sunlight in the country. These views are exemplified in the following quotes:

We live in a country that has so much sun. Greece is blessed with sun. Instead of exploiting our sun, we are still using polluting energy sources. With so much sun, all energy should be from the sun.

(Participant 2)

The sun we have in Greece is much and, if we could leverage it, then we could achieve so much as a country.

(Participant 5)

• Theme 3: The social context of PV adoption

The effect of other people on interviewees’ adoption decision as well as participants’ own influence on their social circle was another identified theme. It appeared that some participants were affected by their families, friends, neighbors or acquaintances, whereas some other participants were the first in their area or neighborhood to adopt this technology, which, in turn, induced others to adopt as well. In relation to the former case, a considerable number of interviewees reported that their decision was affected by their close environment, and, more specifically, by friends or neighbors who had already installed photovoltaics on their rooftops. Specifically, these participants “saw” photovoltaics on the roofs of other houses and “talked” with neighbors or friends or acquaintances who had already installed them. In addition, one participant (Participant 12) reported that he had seen residential photovoltaics when he visited his friends in Germany in the beginning of the 2000s. Once he returned, he started looking for relevant information and eventually decided to have them installed. As at that time no one had them installed in his town, he reported to have led others by his example. There were, however, more participants reporting being the first to install photovoltaics in their area or social circle and, as a result, others were induced to adopt them. The following quotes illustrate how participants affected others:

I was the first to invest here. Some people came and asked me how these things work and how much they cost. After a little time, they installed as well.

(Participant 1)

When I learnt that there is such an option (to have his own photovoltaic system on the roof), I started looking into it. Nobody had, however, installed yet. Almost all of those who installed photovoltaics here, did so long after I had.

(Participant 3)

In addition, two participants stated that some people tried to prevent them from adopting either because they believed that it was not a good investment or because they did not trust the technology of the systems. The efforts to prevent participants from adopting are illustrated in the following quotes:

Most of my friends and acquaintances told me not to do it. They told me that I should not trust the state to keep the agreement for selling the electricity. Very few told me to invest.

(Participant 11)

When I started gathering information about the system, I visited a company that installed such systems. There I talked to two electrical engineers who are supposed to be well educated. They told me not to install and when I asked why they told me ‘you will see’ implying that the systems cause health issues.

(Participant 12)

• Theme 4: The effect of technology on the adoption decision

Most participants described technology as an important aspect that had an explicitly positive effect on their decision to adopt residential photovoltaics. It appears that most respondents (n = 12) were not concerned in the least about the fact that the technology of the systems was relatively new. Instead, most interviewees reported trusting the new technology and some even described them themselves as “in favor of new technology”, “firm believers in technology”, “acutely interested in technology” and “innovators”. At the same time, some participants associated the technology of photovoltaics with science in an effort to explain why they trust the technology of photovoltaics. The following quotes provide illustrative examples of these views:

I believe in new technology. I have complete trust in the technology that is backed by science.

(Participant 10)

Photovoltaics use a new technology. I am definitely a supporter of new technology and science because thanks to these, humans were able to achieve great progress.

(Participant 2)

As someone who is in favor of technology in all areas of life, I did have a personal interest in the technology of photovoltaics. I still like to observe the system and how it works.

(Participant 19)

Even though most interviewees expressed a positive view, there were few participants that reported having many “concerns” and “skepticisms” about the technology of photovoltaics. Moreover, there were reports of experiencing a sense of “insecurity” in relation to this technology (Participants 7, 11 and 18, respectively). Only one participant (Participant 8), however, described the decision to adopt the technology of his residential photovoltaic system as a “great risk”. When asked whether he regretted, he explained that all it took was time to overcome those initial concerns:

At first it was a risk for me. I was worried whether there would be problems with this technology. It was a technology that then we knew very little about. But that was at first. Now I feel okay.

(Participant 8)

• Theme 5: Barriers to the adoption of residential photovoltaics

An important identified theme concerned the barriers that prevent householders from adopting residential photovoltaics. Eight main sub-themes emerged from the interviews as barriers. These involved the high cost of the investment, the lack of trust in the Greek state, insufficient policy support, financial risk, investment taxation, limited grid capacity, and fear and misinformation about the technology of photovoltaic systems, as well as the low number of available licenses.

In relation to the first sub-theme, most participants (n = 12) perceived that the amount of money required for the investment is high and cannot be afforded by citizens who are facing economic difficulties due to the economic crisis. The following quotes exemplify how participants regarded the cost as a barrier:

People do not have the capital or the income to invest anymore. For example, I was personally earning a high income before and I could afford purchasing and installing the system. Today, my income has shrunk significantly and I would not be able to invest.

(Participant 4)

One needs to have a high capital aside in order to make the investment. People do not have so much these days. If I wanted to install photovoltaics today, I would need around 23,000 Euros. I am sure that many people want to install their own system but do not afford it.

(Participant 1)

A lot of people suffer financially. With this energy crisis that we are facing, many people would like to install their own photovoltaic system. But they cannot afford it.

(Participant 7)

The second most cited barrier to investments was the lack of trust in the Greek state. Specifically, participants attributed the lack of trust to the abrupt establishment of Law 4254/2014 which estimated retroactively downward the compensation prices under the feed-in-tariff system. In other words, the majority of interviewees perceived that the abrupt change in the agreed price in 2014 had led people to lose their trust in the Greek state and affected their intention to adopt residential photovoltaics. This was a repeated sub-theme throughout almost two thirds of the interviews. As three participants put it,

People find it risky to invest after the decrease. They think it is a huge risk. They changed the contract once, so they might do it again. People feel great uncertainty.

(Participant 4)

People just see what happened once and do not trust the state. The contract was not kept as agreed and this affects the trust of people. It makes them hesitant.

(Participant 7)

The state was incongruous regarding what had been agreed. We agreed on a specific price but the state in a unilateral way decreased this price. Like it wasn’t enough that we had not received any subsidy to invest. If the price had not decreased, people would see that they could regain their invested capital. After this it is hard for people to invest.

(Participant 12)

There was also a degree of emotional intensity when participants discussed the change in the agreed price. This intensity was evident in the vocabulary they used; for instance, the change was described as “unfair”, “illegal” and “unexpected”, while the state was referred to as “deceiving” and “incongruous” that “broke” the contract. As a result, most participants reported feeling “exasperated” and “angry”.

Beside the changes in prices, participants (n = 8) expressed the view that the state does not provide enough incentives and support for the adoption of residential energy systems. The following quotes provide illustrative examples:

The state does not facilitate the adoption. It provides no incentives to citizens so that they could take this step.

(Participant 2)

The policies of the government do not promote such investments simply because there are no incentives. Instead they promote only large wind parks.

(Participant 9)

Other important cited barriers involved the risk of the investment as well as the high level of taxation on the investment. These barriers are exemplified in the following quotes:

People are afraid of the risk. They risk a lot of money that they do not know whether they will get back.

(Participant 8)

If people take a closer look at this investment, they will see what really happens. In essence, we pay for the infrastructure and the electricity is given to the electricity provider—not even the Public Power Corporation, but those private companies that are behind it. And if that weren’t enough, we also have to pay taxes. This is what people see happening and do not invest.

(Participant 6)

Last Christmas, we (adopters) were notified that we had to pay an unexpected tax of 300 Euros.

(Participant 3)

Other cited barriers involved the lack of space to install the system, the limited number of licenses to install renewable systems, the congestion of the grid and potential adopters’ fear and misinformation about such investments.

4. Discussion

A central topic examined in this study concerned the motives for adopting residential photovoltaics as this information is critical to understand adoption motives and to design effective measures to facilitate residential adoption of photovoltaic systems. Interestingly, our study focused on cases where the adoption had been implemented under the feed-in-tariff scheme which set a guaranteed price for a fixed period of time in which adopters would sell renewable electricity to the grid. Under this scheme, therefore, householders could secure an additional regular income with which they could cover expenses—a motive cited by most interviewees.

Participants’ recognition of the environmental benefits of solar energy in this study should not mean that environmental protection was their primary motive for adopting photovoltaics. The interviews revealed that the decision was primarily driven by the pursuit of economic gains. Namely, even though adopters in this study valued the pro-environmental aspect of residential photovoltaics, it is clear that their primary motive was economic. That being said, the literature on the effect of environmental values on the decision to invest in renewable energy is conflicting. On the one hand, there are studies showing that positive environmental attitudes can render individuals more willing to adopt pro-environmental technological systems [22,40], while, on the other hand, there are studies pointing to the insignificant role of environmental values in such decisions (such as the work of Schelly [20]). Findings from the present study do not confirm most of these previous observations. In this study, it was clear that investors were primarily driven by economic motives and sought either to obtain economic gains or to make a profitable investment per se, while some of them appreciated the pro-environmental aspect of the systems. The interviews revealed that adopters had also attached importance to the environmentally responsible character of the investment without this importance, however, being a determining factor. Hence, this study provides evidence that confirms only the findings of Vasseur and Kemp [44] who had previously noticed that the financial aspects of renewable energy investments are more important than the perceived environmental benefits. This observation also suggests that investments in renewable energy are governed by some level of rationality. Decisions to invest in renewable energy result from careful calculations and rational decision making and, therefore, the decision-making is much like other types of investment (such as investments in stocks, assets and so on) which are based on economic rationality [51,52].

The previous literature had identified that adopters of residential photovoltaic systems tended to combine the investment with certain events of their life, such as retirement, building or renovating the house, or receipt of inheritance [20]. A new insight from this study is that other events can also positively affect adoption decisions. These events involve widowhood and children’s university studies. In the latter case, participants regarded the adoption under the feed-in-tariff scheme as an opportunity to secure an income with which they would cover the anticipated expenses. Likewise, widowhood, which is often accompanied by reduced household income, brought forward the need to obtain an additional income to make ends meet. In addition, building or renovating the house emerged as another event that was linked to investments as it presented an optimal opportunity to install photovoltaic systems. Despite not being a personal life event, the economic crisis was surprisingly also shown to have a positive effect on investment decisions as it appears that the investment with the subsequent payments was seen as a way to maintain living standards and resist the general adverse economic situation. So far, the literature had provided evidence only about the effect of personal life events on investment decisions [20]. However, it now seems that major events, such as the economic crisis, can instill a sense of economic insecurity, which, in turn, can induce individuals to invest in residential energy systems in order to acquire an additional income.

Perceived barriers increase potential adopters’ risk perceptions towards the investment in renewables and can lead to the rejection of the investment [53,54]. For this reason, barriers were examined in this study and it was revealed that the lack of trust in the Greek state was perceived as the most important barrier, because it attached an acute level of perceived risk to the adoption. Lack of trust was ascribed to the decrease in the electricity price that was established with Law 4254/2014. According to this law, the feed-in-tariff compensation prices for existing photovoltaics was estimated retroactively downward which meant that residential adopters would from then on receive less money for the electricity they fed into the grid. There have been major criticisms and negative reactions to this law and, according to interviewees, this decrease has affected not only their own trust but also the trust of potential adopters. As a result, there is wider hesitation to proceed to similar investments and, at the same time, the state is now seen as unreliable. In this regard, it is important to restore trust in the state as this could encourage investments. This could be achieved by ensuring that the legal framework is stable and by keeping the agreed tariffs for producers [34].

In order to obtain advice or information about residential photovoltaic systems, interviewees resorted to their social environment and, in particular, friends, neighbors or acquaintances who had already adopted. Peer consultations recorded here point to the strong effect of potential adopters’ social circle on their decision to invest, and confirm previous studies [22,47]. In such settings, interested individuals are able not only to observe themselves the efficacy of photovoltaic systems, but also to overcome concerns about their safety and operation [55]. As previous adopters serve as an important information source for potential adopters, adopter satisfaction emerges as another important factor in adoption decisions.

There were, however, participants who did not resort to others to reach their decision. These adopters identified themselves as “innovators” because they were the first to install photovoltaics in their area or neighborhood and regarded themselves as setting an example for others. This is in line with earlier literature showing that early adopters recognize in themselves the role of educating others and diffusing new technologies through social networks and the observability of their systems [20,22,56]. Given that investments in renewable energy are a new form of investment, it is reasonable to assume that potential adopters may have concerns about this technology. Nevertheless, almost all adopters in this study exhibited a positive attitude towards renewable technology which was seen as a symbol of progress and scientific development. It may be thus inferred that the technology of renewables had a positive effect on adoption decisions although it was a topic for which participants consulted previous adopters.

5. Conclusions

This interview study has highlighted the factors that have led adopters to install photovoltaics at their residence. To ensure that the deployment of solar energy will continue, it is necessary to examine whether the current investments schemes comply with these factors or how they could be improved to meet them. Specifically, acquiring an additional regular income through the feed-in-tariff system has emerged as the strongest economic driver for adopting residential photovoltaic systems bringing forward the effectiveness of such systems in diffusing solar technology. In addition, adopters viewed it as a safe way to invest their savings and thus campaigns directed to householders should feature this aspect. That being said, the trust of adopters in the state was severely compromised when the price was decreased in spite of the signed contracts indicating that such price reductions may be now acting as inhibiting factors for potential adopters. The study has also highlighted the role of technology in PV adoption; almost all adopters were fascinated by the technology of photovoltaic systems confirming technophilia as a trait of adopters’ profile. Having proceeded to the installation of the systems at their residence, adopters gave a precise account of the most important barriers to adoption with the most important being the high cost followed by investment taxation and limited grid capacity. As these barriers are central in adopter decision making, policymakers need to address them in order to increase the adoption of residential photovoltaics.

Finally, the results of this study should be considered in view of some limitations. Most importantly, it was not possible to ensure the diversification of the sample particularly in terms of sociodemographic characteristics such as location, education level and number of children. Moreover, since our sample included householders who had previously adopted photovoltaics, our conclusions about adoption motives and barriers may only be precise for early adopters; individuals who have adopted or are about to adopt residential photovoltaics may be affected by different factors. As an example, the positive effect of technology enthusiasm reported here may no longer apply as photovoltaics have become more common. In addition, this study has not considered contextual aspects which may be notable, like local discourses on renewable energy and climate change. In view of our results, certain recommendations for future research can be made. As this study has focused only on adoption under the feed-in-tariff system, future research should examine adoption motives and barriers under different adoption schemes such as net-metering programs, which have very recently become available in the study area, and government-sponsored household energy upgrade programs.