Barriers and solutions of solar water heaters in Mexican household

Barriers and solutions of solar water heaters in Mexican household

Solar Energy 188 (2019) 831–838 Contents lists available at ScienceDirect Solar Energy journal homepage: Barriers a...

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Solar Energy 188 (2019) 831–838

Contents lists available at ScienceDirect

Solar Energy journal homepage:

Barriers and solutions of solar water heaters in Mexican household a


L. Salgado-Conrado , Areli Lopez-Montelongo a b


Facultad de Ingeniería Mecánica y Eléctrica, Universidad Autónoma de Coahuila, Carr. Torreón-Matamoros, km 7.5, CP. 27276 Torreón, Coahuila, Mexico Escuela de Arquitectura, Universidad Autónoma de Coahuila, Carr. Torreón-Matamoros, km 7.5, CP. 27276 Torreón, Coahuila, Mexico



Keywords: Solar water heating systems Public politics Green mortgage Governmental programmes Financial schemes

In this study, we identify and describe the barriers that limit the installation of solar water heating (SWH) systems in Mexico and the manner in which the Mexican government has been working toward overcoming these challenges. Data regarding architectural, technical, economic, marketing, social, and political barriers were collected from official governmental publications, Mexican journals, and articles, and compared with results from similar research articles. Our results revealed that the governmental programmes have positively motivated the adoption of SWH systems. However, issues related to the structural conditions of buildings, low income, and access to water limit their use. Therefore, these issues should be included in the governmental strategies.

1. Introduction The energy sector is an important factor in the growth of countries due to the close relationship between gross domestic product and energy consumption. According to the national energy balances, Mexico consumed 4895.79 PJ of energy in 2016, of which 45.4% corresponded to the transport sector, 30.7% to the industrial sector, 17.5% to the residential sector, 3.3% to the agricultural sector, and 3.2% to nonenergetic uses (Alexandri et al., 2015; Beltrán et al., 2016; IEA, 2016). As shown in Fig. 1, the residential area consumes large quantities of energy, which in turns causes adverse environmental effects. In particular, in 2014 the CONAPO (2014) (Consejo Nacional de Población in Spanish) showed that 65% of the energy consumed in the residential sector at the national level was used for water heating, 17.2% for cooking, and 14% for food preservation and heating/cooling, as illustrated in Fig. 2. More precisely, households in urban areas consumed the highest amount of energy per month (5084.1 MJ, equivalent to 67.7% of the wasted energy), while the mixed and rural households used 2915.5 MJ (59.9%) and 1611.4 MJ (51.6%), respectively (Pinzon et al., 2015; Romero-Hernandez et al., 2015). Reports presented by SENER (Secretaría de Energía in Spanish) indicated that 85.7% of Mexico’s energy came from fossil fuels, mainly

crude oil (62.6%) and natural gas (23.1%). Meanwhile, just 8.4% of the energy was produced using renewable energy sources, with biomass and biogas accounting for 4.7%, hydro energy for 1.4% and geothermal, wind, and solar energies combined accounting for 2.3% (SENER, 2018). Efforts to reduce the dependence on crude oil in Mexico have resulted, among other initiatives, in the increased use of renewable energies, due to their potential to alleviate current environmental and energy price problems. However, the use renewable energy is not developing as quickly as it could. The supply of energy for thermal applications from renewable energy sources registered an annual growth rate of only 2.8% over the period of 2001–2011 (MundoHernández et al., 2014; Prospective, 2011). To get a definitive perspective of the existing SWHs in Mexico, INEGI (Instituto Nacional de Estadística y Geografía in Spanish) reported that at the national level, 50.4% of Mexican households do not have water heaters while 42.82% of the households use some type of water heater based mainly on the consumption of qualified petroleum gas (LPG). By the end of 2015, it was estimated that 3.18% of Mexican households had installed some type of SWH system (Velázquez and Arturo, 2014), as shown in Fig. 3. Considering the percentages mentioned above, INEGI published a document in 2016 on the use of solar water heaters in various Mexico (Fig. 4). According to this study,

Abbreviations: ANES, Asociación Nacional de Energía Solar; CONAE, Comisión Nacional para el Ahorro de Energía; CONAPO, Consejo Nacional de Población; CONAVI, Comisión Nacional de Vivienda; CONOCER, Consejo Nacional de Normalización y Certificación de Competencias Laborales; CONUEE, Comisión Nacional para el Uso Eficiente de la Energía; FIDE, Fideicomiso para el Ahorro de Energía Eléctrica; FOTEASE, Fondo para la Transición Energética y el Aprovechamiento Sustentable de la Energía; FOVISSSTE, Fondo de la Vivienda del Instituto de Seguridad y Servicios Sociales de los Trabajadores del Estado; GIZ, Deutsche Gesellschaft für Internationale Zusammenarbeit; MX, Mexican pesos; NAMA, Mexicana de Vivienda Sustentable; IMEVIS, Instituto Mexiquense de la Vivienda Social; INEGI, Instituto Nacional de Estadística y Geografía; INFONAVIT, Instituto del Fondo Nacional de la Vivienda para los Trabajadores; LPG, Liquefied petroleum gas; PROCALSOL, Programa para la Promoción de Calentadores Solares de Agua en México; SENER, Secretaría de Energía; SWH, Solar water heater Received 7 December 2018; Received in revised form 8 April 2019; Accepted 6 June 2019 0038-092X/ © 2019 International Solar Energy Society. Published by Elsevier Ltd. All rights reserved.

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Non-energy use

various consumer sectors (residential, services, and industrial). There are barriers that hinder this development and the related technological change involved; many have a commercial scope such as lack of diffusion or scarce financing, but others are of political and social nature. Therefore, the objective of the current paper is to investigate the barriers that limit the adoption and dissemination of SWH systems in a variety of contexts (architectural, political, social, and economic) and present the most relevant solutions that have been proposed to eliminate these barriers. Due to the difficulty in obtaining research papers regarding the development of solar energy in Mexico, much of the information in this paper was obtained from official governmental online publications and Mexican journals and articles. The paper is organised in the following manner. In Section 2, we describe barriers to and solutions for implementation of SWH systems. An analysis of architectural, technical, economic and financial, marketing, and social and political is included. In Section 3, we compared with results from similar research articles. Lastly, Section 4 summarises the primary conclusions.

8.9% Other 11.5%

Industry 32%

Residential 21.9%

Transport 28.8%

Fig. 1. Distribution of sector-wise energy consumption in Mexico (Beltrán et al., 2016).

Food preservation

11% 25.5%

Food cooking


22.1% 15.4% 17%


2. Barriers to and solutions for implementation of SWH systems



7.4% 3.3% 7% 2.4% 7% 1.3%

Although solar technology has advanced tremendously in recent years, there are still various barriers to its implementation. These barriers can be grouped into five categories: architectural, technical, economic and financial, marketing, and social and political. The following sections show the barriers and solutions of the implementation of SWH systems in Mexico.

Heating/cooling Other Lighting

2.1. Household and architecture-related barriers

National 65%

The need to reduce CO2 emissions has led experts to examine and propose solutions for barriers that prevent the installation of SWH systems in Mexican households. In general, the architectural integration of SWH systems presents three fundamental difficulties: availability of a suitable installation area, modification in buildings and cost. Concerning the criteria of installation area, it is recommended that SWH systems be installed in a sunny area and with southern orientation in the Northern Hemisphere (Rosas-Flores et al., 2016); the installation area required for an SWH vacuum tube system of 150L is 2.6 m2 (Technical, 2016). In Mexico, all buildings differ greatly, which makes it challenging install solar technologies in homes. We found that especially in urban zones, neighbouring buildings can shade the SWH equipment and thus reduce the incident solar radiation. In other cases, the distance between the solar energy system and the point of service is large, and the thermal efficiency of the devices is thus negatively affected by heat losses (Manufacturers and marketers of SWH systems, 2017). Moreover, the weight of SWH system containing water (between 250 and 290 kg for an SWH system of 150L) (Integration, 2015; IEM, 2018) has in some cases damaged building structures due to deterioration of the housing caused by a lack of maintenance. Such structural damage had affected 9.2 million houses as of 2016, which is equivalent to 33.5% of the total numbers of inhabited private homes (CONAVI, 2016). Regarding costs, housing developers and occupants tend to focus on investment costs. As part of the strategy to promote SWH system, the government created the ’green mortgage programme’ through the INFONAVIT (Instituto del Fondo Nacional de la Vivienda para los Trabajadores in Spanish), which offers a financing scheme to assist with the additional costs of installation and use of SWH systems. The green mortgage programme is based on the calculation of future accumulated savings resulting from decreased expenditure on gas. In its programme for the promotion of renewable energies (Flores, 2006), CONAE (Comisión Nacional para el Ahorro de Energía in Spanish) showed that an INFONAVIT credit for a new house with an SWH system is MX$ 9200 below the mortgage credit for a house without a SHW system (Table 1),

Urban 67.6% Mixed 59.9% Rural 51.6%

Water heating

Fig. 2. Percentage of energy consumption by end users in Mexican households (Beltrán et al., 2016).

50.4% without water heater

42.82% with water heater

39.64% without solar water

3.18% with solar water heater Fig. 3. Mexican households with and without water heaters (INEGI, 2017).

Aguascalientes (16.1%), Zacatecas (13.2%), Jalisco (10.5%), Michoacan (7.6%), and Guanajuato (7.1%) have the highest use of SWH systems (INEGIb, 2017). This indicates that Mexico has a large potential to increase the use of SWH systems within the residential sector, since Mexico is the second largest economy in Latin America and covers a very large territory. Its favourable geographic location, which extends from 14°N to 33° N and from 118°W to 86°W, allows for the receipt of an average global irradiation between 4.4 kWh/m2 and 6.3 kWh/m2 per day (PROMEXICO, 2017; Rosas-Flores et al., 2016). Thus, there is a great potential for generation of projects related to the use of solar energy (Quej et al., 2017). Despite the strong solar energy potential in Mexico, the use of solar energy for water heating has not been fully taken advantage of by the 832

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Aguascalientes Zacatecas Jalisco Michoacan Guanajuato Queretaro Durango Tlaxcala Durango San Luis Potosi Colima Chihuahua Puebla Baja California Mexico State Mexico City Nayarit Morelia Coahuila Baja California Sur Nuevo Leon Tamaulipas Quintana Roo Oaxaca Sinaloa Veracruz Sonora Yucatan Campeche Gerrero Chiapas Tabasco






6.2 4.8

5.5 5.2

3.0 2.9 2.9 2.7 2.7 2.6 2.2 1.9 1.6 1.3 1.2 0.9 0.8 0.7 0.6 0.6 0.6 0.6 0.5 0.4 0.4 0.3 0.3 Fig. 4. Percentage of households with a solar water heater in Mexico, by region (INEGI, 2017).

which is due to the prior planning regarding hydraulic systems. The government expects that consumers weigh the savings made possible by an SWH system via reduced expenditure on gas in their decision to acquire this credit. The consumer without INFONAVIT credit then faces three major costs: equipment costs (no greater than MX$ 32,000 depending on the specific SWH model (PROFECOc, 2018), installation costs (starting with MX$ 1000 and increasing), and modification costs. Tables 2 and 3 show costs of SWH systems with natural circulation and forced circulation, respectively. Costs related to the first two factors will be addressed in Section 4. Necessary modification arising from the fact that the majority of Mexican houses do not follow the architectural plans for the house could further increase the investment costs. Isunza (2011) reported that 40.1% of homes were built in an improvised manner by a mason, 40.3% by a master builder without a blueprint, 2% by a hired construction company, and only 0.6% involving the services of architects or engineers. In this sense, the consumer must consider a long-term costbenefit analysis long with the investment costs.

installers and suppliers under the ECO325 standard (RENEC, 2017; IINFONAVITa, 2018). A data-sheet model was also created to explain the technical characteristics, use, installation, and maintenance of the products (Solar thermal world document, 2018). As a consequence of low interest in SWH product certification and the increase in user complaints about failures of these devices, the Mexican government established an obligatory norm, NOM-027-ENER/ SCFI 2018. This regulatory framework describes thermal performance, gas saving potential, and safety requirements with which all SWH equipment with a backup LP or natural gas water heater must comply, as well as the specifications, test methods, and labelling of these products (NOM, 2018). The result of this has been unfavourable for the majority manufacturers and installers, since their products were of low quality. To comply with this obligatory framework, manufacturers have increased their equipment costs by MX$ 2000, which increases investment costs for the consumer (Cabecera, 2018). Under this context, Chinese solar water collectors dominates the production and the sales of SWH collectors in Mexico. PROMEXICO (2017) estimated that Mexico imports 24.6 million dollars and exports only 10,000 dollars of SWH systems. It is evident that Mexican industry needs the support of government programs to record further growth of the solar industry.

2.2. Technical barriers Over the past decade, Mexico has intensified its efforts to encourage the use of SWH systems. However, only 1 in every 20 Mexican households has SWH equipment, due to the poor quality of the products available and problems associated with improper installation (SWH, 2017). To overcome these problems, GIZ (Deutsche Gesellschaft für Internationale Zusammenarbeit in Deutsch) proposed the formation of a technical group that inspects the installation of SWH systems in Mexican homes (GIZb, 2017). This technical group created a regulatory framework that establishes test methods to determine thermal performance and functionality of SWH systems, as shown in Table 4. In 2014, CONOCER (Consejo Nacional de Normalización y Certificación de Competencias Laborales in Spanish) and INFONAVIT applied this framework in more than 3300 households in Aguascalientes, Mexico City, Durango, Jalisco, Michoacan, Nuevo Leon, Morelos, San Luis Potosi, Veracruz, Zacatecas and Guanajuato. This project involved certified

2.3. Economic and financial barriers The choice to adopt an SWH system is determined by the capital costs, which include the value of the product, installation, and modifications in the hydraulic line of the building, as well as the income level of the consumer. Based on the national occupation and employment survey (ENOE) of 2017, the 96.6% of the population is economically active, of which 69.8% have informal employment (ENOE, 2017). The most recent data from INEGI show that only 1.7% of citizens receive more than MX$ 20,000 per month, 10% of the population earns less than MX$ 1,500 per month (INEGIb, 2017). If we compare the average costs of a natural or forced circulation SWH system income of the population, it can be deduced that the average consumer cannot 833

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0 4129


−102 4212


Monthly fuel savings (MX$) Monthly mortgage payment (MX$)

Although the number of companies offering SWH systems has increased from 46 in 2010 to more than 600 in 2014 (ANES, 2015), they continue experiencing difficulties marketing their solar systems. Mexico has intensified its efforts to encourage the use of solar equipment. However, the reception and use of the SWH equipment by the general public is still incipient. In this sense, the Mexican government invested MX$ 4,500,000 in advertising campaigns for SWH devices (Flores, 2006). One of its strategies was to encourage the adoption of SWH technology through the use of credit card over a period of months and reduction of the annual interest rates charged by Banamex, Bancomer, Santander, and Banorte banks, as shown in Fig. 6. Not only have the annual interest rates of the banks been reduced, but the interest rates of governmental programmes such as the INFONAVIT green mortgage have also decreased by 2% over the last 5 years, as shown in Fig. 7. Another strategy used was to link sellers and developers of housing projects through conferences and seminars on SWH systems (Econergy, 2018; PROCOBRE, 2018). Its primary aim was to establish financing mechanisms accessible to the consumer. To help the local market, CONUEE (Comisión Nacional para el Uso Eficiente de la Energía in Spanish), ANES (Asociación Nacional de Energía Solar in Spanish), and PROCALSOL members elaborated strategies for the diffusion of SWH systems as well as various financing alternatives (ANES, 2015; CONUEE, 2018; PROCALSOL, 2009). The IMEVIS (2018) (Instituto Mexiquense de la Vivienda Social in Spanish) has promoted the sale of SWH parts for household equipment at reduced prices. Further, the government has involved INFONAVIT, FOVISSSTE (Fondo de la Vivienda del Instituto de Seguridad y Servicios Sociales de los Trabajadores del Estado in Spanish), Financiera Hipotecaria Federal, CONAVI (Comisión Nacional de Vivienda in Spanish), FIDE (Fideicomiso para el Ahorro de Energía Eléctrica in Spanish), FOTEASE (Fondo para la Transición Energética y el Aprovechamiento Sustentable de la Energía), as well as the manufacturers and importers themselves in its projects for promoting solar technologies (Flores, 2006). However, all these strategies are overshadowed by the lack of demonstration of the devices in the stores and the lack of price control

400,000 400,000


409,200 400,000

House with LPG water heater and SWH system House with LPG water heater only


Deadline payment of mortgage term (years) Cost of housing (MX$)

Mortgage (MX$)

afford the product. Tables 3 and 4 show the costs of natural and forcedcirculation SWH systems (PROFECOb, 2016), respectively. As the consumer is generally unable to cover the cost of SWH equipment, in 2007, the Mexican government created a programme for the promotion of solar water heaters in Mexico called PROCALSOL (PROCALSOL, 2009), which evaluated financial alternatives for the economically active population. Fig. 5 indicates that credit card, FONACOT credit and mortgage credit have been consolidated as viable options for the financing of solar equipment in the last years (Bivica, 2011). FONACOT is a governmental institution, which was created to give financial credits to workers with more than 3 years of seniority in the same job. In the case of a consumer with a housing mortgage credit and with low annual payments, the investment recovery period is short (Table 5). In the case of a consumer without mortgage credit, the use of credit card offers without interest. For people with incomes lower than MX$ 353.44, the government provides a subsidy of MX$ 30,000. CONAE, SENER, and SHCP (CONAE, 2018; SENER, 2018; SHCP, 2018) promote economic mechanisms supporting the installation of SWH systems by reducing initial investment through the reduction of interest rates and financing schemes. The financing schemes include the acquisition of equipment through deferred payments, interest -free periods, credits from department stores, and other methods. Additionally, CONAE in coordination with the authorities responsible for the promotion and financing of housing in Mexico, seeks to integrate financing for new houses with the cost of SWH equipment into overall favourable rates for consumers (CONAE, 2018). 2.4. Market-related barriers


Table 1 Monthly mortgage payments with and without SWH system (Cooperación Alemania, 2015)

Actual mortgage cost per month (MX$)

L. Salgado-Conrado and A. Lopez-Montelongo


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Table 2 Costs of a solar water heater with natural circulation (Flores, 2006). Capacity of tank (L)

Evacuated tubes



Capacity of tank (L)


15 10 10 10 12 15 15 12 14 18 20 16 16 20 24

3 3 3 3–4 4–5 5 4 4–5 5–6 5 6 6–7 5–7 6 8

$2920 $4421 $4502 $7770 $5985 $6,155 $7073 $8310 $9100 $4274 $8171 $10,080 $7980 $8000 $10,050

221 242 250 272 300

130 150

172 180 188 200 214

315 350 400 425 245 500 Note:

Evacuated tubes

18 20 25 24 24 30 30 26 25 30 32 36 36 40 Installation costs are not included


Cost (MX$)

7–8 8–9 7 10–11 8–9 8 10 11–12 9–12 12–13 10–13 14–15 11–17 14–18

11,270 12,170 9816 12,980 11,970 12,563 12,960 13,580 13,965 15,180 15,960 16,430 17,955 $19,950

Table 3 Costs of solar water heater with forced circulation (ENOE, 2017). Capacity of tank (L)

Evacuated tubes


Cost (MX$)


15 15 18 20 24 24 25 24 30 30

4 5 5 6 5 7 7 5 10 8

9126 10,425 9728 13,993 32,000 21,395 15,575 22,500 25,062 16,207

180 200 215 250 270 280 300

Fig. 5. Unit costs per shower for different financing alternatives (Econergy, 2018).

renewable energy in 2014 (Amézquita, 2018) However, this offering has been taken advantage of very rarely due to ignorance of the energy reform.

Note: The installation costs are not included.

of SWH systems. In this context, it could be argued that there is not any strategy.

2.6. Socio-cultural barriers

2.5. Political barriers

As mentioned in Section 2.3, one of the most significant problems in Mexico is income inequality; 60% of the population has low income and between 36% and 46% of the population lives in poverty (SEDESOL, 2018). In contrast, less than 2% of the population has a high income. A survey of the expenditures of households in Mexico (INEGIa, 2016) indicated that the monthly expense of a Mexican family is approximately MX$ 9380 monthly. As the average Mexican salary is around MX$ 5420 per month, people often work two or more jobs to cover their expenditure. This indicates that a large percentage of the economically active population would be uninterested in adopting a SWH system. Another socio-cultural barrier is the availability of piped water and access to water in households (PROFECOa, 2016). The INEGI data showed that 25% of the population does not have access to direct water in their homes, corresponding to 8,411,920 homes (INEGI, 2017). Understandably, the affected population is more focused on finding solutions to the problems of shortage water supply and its quality control, and the lack of modern infrastructure. Finally, we found that the Mexican government has incorporated

Given the current situation regarding climate change, the Mexican government has carried out actions that contribute to the diffusion and adoption of SWH systems. Their primary efforts have focused on standards and certification of solar equipment, outreach campaigns, financial incentives, and industry support, as shown in Table 6. Some governmental programmes that have been implemented include: the programme for the promotion of SWH (2008–2012), which installed 2.2 million m2 of SWH systems in homes (PROCALSOL, 2009); the “25,000 Techos solares’ projects” (2008–2012) used to encourage the growth of the green housing market in urban areas (GIZ, 2014); the sustainable housing programme (2008–2012) assigned to propose and implement financing schemes (Sustainable housing program, 2016); and the INFONAVIT green mortgage programme which provided bonds and between MX$ 9800.86 and MX$ 49004.80 in credits for the acquisition of ecotechnologies (INFONAVITb, 2018; INFONAVITc, 2018). As part of the initiatives for the use of solar energy in Mexico, in 2014 the government implemented reduction for companies using Table 4 Norm regulating solar water heating systems in Mexico. Standard/ Norm


NMX-ES-001-NORMEX 2005 NMX-ES-002-NORMEX 2007 NMX-ES-003-NORMEX 2007 DTESTV EC0325 EC0473

Thermal performance and functionality of solar collectors for water heating. Test methods and labelling. Definitions and Terminology. Minimum requirements for the installation of SWH systems. Thermal evaluation of SWH systems. Testing method (obligatory for the green mortgage programme of INFONAVIT). Installation of a solar heating system for thermosiphoned water in sustainable housing. Installation of an SWH system with forced circulation hot water tank.


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Table 5 Financial alternatives for the acquisition of SWH systems (Bivica, 2011; CONAVI, 2016). Type of financing

Cash payment Credit card FONACOT Department store INFONAVIT mortgage Commercial mortgage Gas distributor CFE, TELMEX ∗

Cost of solar water heater with installation (MX$)

Annual Payment (MX$)

Payment Deadline (years)

VPN in 10 years (MX$)

Investment recovery (years)


Natural gas


Natural gas

9200 9200 9200 9200 9200 9200 9200 12,000

– 2554.79 2307.22 3507.07 936.73 1150.28 3393.44 9168

– 5 5 3 20 20 3 1.5

−518 −765 −43 −281 2594 1662 −3390 –

−2560 −3130 −2408 −2646 229 −703 −4692 –

5.98 7.99 7.47 7.03 2.55 3.93 6.87 –

7.55 10.30 9.69 9.17 6.43 9.19 8.99 –

VPN (Present Net Value) 1 MX$ = 0.078 Euro = 0.094 US$

3. Discussion We demonstrated previously that several solutions have been implemented to eliminate or diminish the barrier to the installation and dissemination of SWH systems. The results confirm that the anticipated planning for an SWH system reduces the investment cost and avoids damage to building structures due to modifications. Given that the certification of SWH equipment experienced little participation until February 2017 when 600 certifications were granted (Flores, 2006), the obligatory application of NOM-027-ENER/SCFI 2018 has improved SWH equipment overall, but increased the SWH equipment costs by MX $ 2000 (Cabecera, 2018). In the implementation of this regulation 400 manufacturers and installers were negatively affected due to their products being of low quality (El financiero newspaper, 2018). We also found that the green mortgage programme encourages the adoption of SWH systems through the eco-technology bonus granted in the event of acquiring a new INFONAVIT housing credit. Similar situations have been reported previously (Morapakala, 2011;Veeraboina and Ratnam, 2012; Purohit and Michaelowa, 2008), where the authors described that technical incompetence in installation, lack of product certification, and difficulty in finding retail outlets were the strongest barriers to SWH utilisation. To resolve these issues in the case of India, the Indian government created the standard. IS 12933 that describes testing methods, instrumentation for testing, thermal performance and outdoor tests of SWH equipment. With these standards and specifications, India increased their total SWH installation 0.8 million m2 to 3.53 million m2 between 2004 and 2010. Inn addition, the government implemented a soft loan scheme with an interest subsidy limiting the effective maximum interest rate to 5% (2% for domestic users, 3% for institutional users and 5% for industrial/commercial users). This strategy generated low demand for SWH systems due to the high interest rates involved, and rural citizens still could not afford this technology. Ruble and El Khoury (2013) highlighted persist barriers in Lebanon’s SWH market and how governmental policy initiatives have expanded the use of SWH technology. To increase consumer confidence in SWH systems, the Lebanese government established obligatory certification of SWH systems and their components under the NL-EN-12976

Fig. 6. Annual interest rate on bank credit cards for SWH systems (2004–2015) (PROCOBRE, 2018).

Fig. 7. Annual average interest rates for mortgage loans (2004–2015) (PROCOBRE, 2018).

training programmes in schools, universities, and other professional groups regarding the use of solar energy and its benefits. This solution has been slow because the programmes lack economic support and energy sustainability projects (Gutiérrez et al., 2010).

Table 6 Actions implemented by the Mexican government.

Insolation Residential energy consumption growth Country credit rating Access to finance Doing business Manufacturing capacity

SWH market penetration SWH market growth Competitiveness: Payback period Competitiveness: Heating fuel subsidy Industry association


Standards/Certification SWH load programmes Outreach campaigns Financial incentives Industry support

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and NL-EN-12976 standards. Also, Lebanese centre for energy conservation (LCEC) has established a pre-qualification scheme for the solar energy service companies to ensure they comply with a sufficient product quality, after sales services and technical skills of employees, product information, and guarantees. Its financing programmes offered the possibility to obtain SWH equipment through interest-free loans over a one to five year period with participant banks and subsidisation schemes of about USD$ 200. Yu and Gibbs (2018) showed that in China, architects, building designers, and suppliers all lacked knowledge on SWH systems, which was a major obstacle in the adoption of these systems. Additionally, the lack of quality control for these devices and inappropriate government intervention, imposing strict industry standards and the obligatory installation of SWH systems, have led to the rejection of these systems and conflicts of interest between SHW suppliers, manufacturers, and local government. The Spanish government has promoted solar thermal energy through three different incentives: tax incentives, non-refundable grants and favourable lines of credit. Further, they have created legislative regulations that force the use of this type of energy in construction, avoiding conflicts of interest. However, their strategies have been found to be insufficient due to administrative barriers, a crisis in the construction sector, and uncertainty regarding the maintenance of subsidies (Pablo-Romero et al., 2013). Another aspect to be considered in the implementation of the SWH in Mexico is its Life Cycle Analysis. In Mexico, there have not been published works of CO2 eq. In (SWH, 2017), the Mexican government estimated that the SHW’s sales are approximately 400,000 m2 per year, which represents approximately 25–30 million dollars annually. The avoided emissions of GHG would be 2.1 million tons of CO2eq considering a lifetime 10 years, which would mean environmental profitability of 57 dollars per tCO2eq avoided. When comparing this information with Koroneos data’s (2012), the results are consistent, which means that the SWH show great environmental benet in comparison with natural gas or electric heaters. However, when analysing the environmental implications of SHWS considering the production, use, maintenance and end-of-life stages, these solar technology can be provide an impact of 70% of kg CO2 eq during the installation, following by the use phase, with approximately 22%, and the end of life with 8% (Zambrana-Vasquez et al., 2015). The mentioned above indicates that it is required to establish additional scientific criteria for the design and installation of SHWS. The challenges faced up many countries in the dissemination of SWH systems point to a dire need for policies, strategies, and solutions. Based on the information obtained from the countries discussed above, it is seen as imperative that synergies are established between government, manufacturers, distributors, and consumers in Mexico to avoid conflicts of interest and the rejection of SWH device. Governmental programmes represent great opportunities for the development, diffusion, and adoption of solar technology. The challenges are related to stimulation the research and development of SWH systems with using domestic materials in Mexico, development of programmes for rural communities which consider the different construction materials of the houses, income levels, and methods of control and verification of solar systems acquired, and a flexible framework for housing developers and manufacturers.

adoption of WHS systems. Therefore, it is concluded that consideration of these criteria in the governmental programmes could successfully increase the adoption of the SWH technology. Declaration of Competing Interest Noting declared. Acknowledgements The authors acknowledge financial support from CONACYT (México), and PRODEP. References Alexandri Rionda Rafael, et al., 2015. Prospective of renewable energies 2016–2020. Renovables_2016-2030.pdf (accessed October 2018). Amézquita Daniel, 2018. Tax benefits and companies of Renewable Energies document. (accessed August 2018). ANES, 2015. Mexican association of solar energy (ANES). (accessed October 2018). Beltrán Rodríguez Leonardo, et al., 2016. National Energy Balances of Mexico. https:// 2016__2_.pdf (accessed August 2018). Bivica, 2011. Program for the promotion of solar heaters. calentadores-agua.pdf (accessed September 2018). Cabecera newspaper, 2018. (accessed October 2018). CONAE, 2018. National Commission for the Efficient Use of Energy. plataforma/ (accessed September 2018). CONAPO, 2014. National Council of Population. (accessed September 2018). CONAVI, 2016. Análisis del rezago habitacional y grupos vulnerables en México: 2008–2016. habitacional_2008_2016.pdf (accessed October 2018). CONUEE, 2018. National Commission for the Efficient Use of Energy. conuee (accessed September 2018). Econergy Mexico, 2018. (accessed August 2018). El financiero newspaper, 2018. (accessed 21st October 2018). ENOE, 2017. National occupation and employment survey of 2017. mx/proyectos/enchogares/regulares/enoe/ (accessed October 2018). Flores, Alejandro Patiño, et al., 2006. Alternativas Financieras para la Promoción del Uso de Calentadores Solares de Agua (CSA) en el Sector Doméstico Mexicano. (accessed July 2018). GIZ, 2014. Program of 25,000 solar roofs. html (accessed October 2018). GIZ, 2017. Deutsche Gesellschaft für Internationale Zusammenarbeit (GIZ). en/worldwide/23041.html (accessed October 2018). Gutiérrez Barba, et al., 2010. El plan de acción para el desarrollo sustentable en las instituciones de educación superior: Escenarios posibles. Revista de la educación superior 39.154, 111–132. IEA, 2016. Indicators of Energy Efficiency: Essential Bases for the Establishment of Policies. (accessed August 2018). IEM solar water heater, 2018. Calentador.pdf (accessed August 2018). IMEVIS, 2018. Instituto Mexiquense de la Vivienda Social (IMEVIS). http://imevis. (accessed August 2018). INEGI, 2016. Survey of the income-expenditures of households in Mexico. www.beta. (accessed July 2018). INEGI, 2017. Instituto Nacional de Estadística y Geografía (INEGI). (accessed October 2018). INFONAVIT. Institute of the National Fund for Housing for Workers. mx (accessed August 2018). INFONAVITb, 2018. Green mortgage program. connect/526fbfc4-c222-4cca-95ae-afe1dffde803/Manual_Explicativo_de_Vivienda_ Ecologica.pdf?MOD=AJPERES&CVID=mrGHKf1&CVID=lGBnpqs&CVID=lGBnpqs (accessed September 2018). INFONAVITc, 2018. Manual Explicativo de la Vivienda Ecologica 2018 Version 2.0. CVID=mrGHKf1&CVID=l (accessed Octuber 2018). Integration of thermal solar facilities in buildings, 2015. A quick guide for architects and

4. Conclusions This study attempts to identify and analyse the major barriers to the complementation of SWH system in Mexico. Five barriers have been described: architectural, technical, economic and financial, marketing, and social and political barriers. A large number of attempts have been made to minimise and eliminate low quality SWH systems, inadequate installation, limited financing schemes, and lack of social acceptance. However, the structural condition of buildings, low income levels, and insufficient access to water in households limit the dissemination and 837

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