**1. Introduction**

Nations in the developed world are transitioning towards the use of renewable energy sources (RES) as the main resource for meeting energy needs because of its potential to address issues of climate change [1]. As applications in the economically developed countries have helped to drive down cost, low and middle-income countries are also increasingly looking towards RES. Up until 2008, however, most countries had not included PV technology into their electricity generation mix [2]. One of the reasons is that PV technology lacked cost competitiveness when compared to other RES like wind power as well as when compared to power generation based on fossil fuels.

In general, in terms of installations, fossil fuel-based technologies have had an upper hand over PV on a global scale. Concerns, however, have mounted over the steady increase of greenhouse gas emissions, which has been prompting governments to adopt planning practices and policies [3] as well as subsidies favouring RES [4]. Such concerns as well as reductions in cost of PV technology have resulted in increased uptake and technology development in parallel.

The cost of PV systems in Germany for example, has been declining steadily and significantly over the past decade; this is attributed to the rapid technological development spurred by government subsidies [5]. Installed costs between 2006 and 2013 declined by an average of 16% per year. By the first quarter of 2017, the typical cost of solar PV in typical roof top applications had fallen to 1640 EUR per kWp from over 5000 EUR per kWp in 2006 [6].

This decrease in installation cost took place as installed capacity increased in the same time period. By the end of 2018, 1.5 million rooftop installations had thus been installed in Germany [7]—a country of approximately 42 million households [8].

Concurrently, the development of PV technology that resulted in increased efficiency from 15% to over 30% [9]. The decreasing module costs combined with increasing efficiencies have resulted in a compound decrease in the cost of electricity from PV modules. Consequently, in the global context, PV has become much more competitive and the cumulative capacity of PV technology has increased significantly [10].

The development has been uneven across the globe though. In a study by [11], the current status and outlook of RES in Morocco was assessed. Morocco has exceptional good potential for the exploitation of particularly PV, but also good prospects for wind power—two technologies already adopted in the country. In the study, challenges and barriers to the development of RES and the national strategy for energy security and how the challenges will be met was evaluated using time series method. Results of the study showed that in the long term, towards 2030, wind and solar power can be injected without creating constraints of transit on the solar and wind power.

Kenya, on the other hand is neither as ambition nor as successful in terms of PV development in spite of a good solar radiation. Data show that the total installed PV capacity in Kenya was only about 50.25 MWp as of 2019 [12]. This capacity is marginal compared to the total installed power production capacity of approximately 5000 MW in Kenya. PV is projected to grow at 15% annually [12] in Kenya mainly attributed to the decreasing prices and PV thus becoming more competitive, but this is still marginal compared to potentials, and in many case developments is on off-grid systems. For these applications, in addition to wishing to save money, consumers like the idea of being autonomous [13]—a motivational factor also seen in e.g., Denmark, where PV owners may even opt for costly storage systems to increase their level of electricity autonomy [14].

While a 15% annual increase in other areas would seem high, it does, however, not suffice for a transition as this expansion rate would require many decades of installations. Also, concurrently, an increase in income and a process of urbanization is generating increases in fossil fuel usage in Kenya [15] that also needs to be balanced through increased RES exploitation. Besides, the peak demand for electricity increased by 3.6% from 2018 to 2019, and the peak is projected to increase from 1802 MW in 2018 to 15,000 MW by 2030 [12]. More RES development is thus needed and any barriers have to be overcome.

In fact, the Kenyan electricity generation mix (See Figure 1) shows that fossil fuels only provided approximately one quarter of the electricity while hydropower and geothermal had even more significant shares of approximately 30% each. Thus Kenya is heavily supplied by RES as it is.

Kenya has a high potential for the use of geothermal energy, with potentials to increase from currently about 200 MW up towards 10 GW [16]. The exploitation faces several challenges however including rising investment charges, increasing resource exploration and expansion risks, land-use conflicts, inadequate expertise, and high investment in grid infrastructure due to long distances from geothermal sites to existing load centres [17].

Hydropower in Kenya is mainly in the form of dammed hydro power plants with production susceptible to drought. This results in a less-than-optimal robustness and outright load shedding [18]. Pumped hydro storage could provide more flexibility by also enabling also excess generation from wind and PV to be stored for later use. Wind and PV could thus assist Kenyan hydropower and making it more robust against drought.

**Figure 1.** Kenyan electricity production mix shares in 2019. Based on data from [12].

Also, both hydropower and geothermal projects are characterised by long lead-times, thus in spite of potentials, these may not be adequate to fill the projected production gap.

Thus, as it is—and also combined with other constraints—the electricity system in Kenya suffers from frequent power outages. In a typical month, firms and homesteads connected to the grid experience on an average about six power outages, each lasting approximately five hours [19]. The economic cost of power interruptions is assessed to be about 7.1% of the power distribution companies' sales. Power outages therefore have a significant economic cost on businesses [19] and in turn on the Kenyan society.

Kenya has a large potential for PV since it is located near the equator, which provides it with a high insolation [18]. The insolation levels in Kenya and the large rural population is a stimulant for the penetration of solar power. According to [20] about 70% of the land area in Kenya has the potential of receiving approximately 5 kWh/m2/day throughout the year with an annual mean radiation of 6.98 kWh/m2.

A literature survey on the integration of PV in the electricity generation mix reveals, however, that focus is predominantly on Europe and United States of America. Little attention has been paid to emerging economies such as Kenya where electricity production and demand is expected to grow considerably in the coming years. Besides, there is room for adopting an infrastructure capable of meeting the future power demands using RES from the outset—and given the resource availability—notably PV.

Also, no study has highlighted the potential of and possible barriers to solar PV generation where hydropower already exists. Studies on PV in Kenya have a leaning towards ensuring access to electricity in areas located far away from the national grid as opposed to grid-connected projects [21,22]. This of course limits the analyses of interplay with hydropower. The only exceptions to off-grid analyses to date are viability studies in South Africa [23] and a review focussing on the development of mini-grids [24]. This paper therefore focuses on the prospects of balancing grid-connected PV systems with hydropower generation.

In spite of the demonstrated large potential of PV utilisation in Kenya, current exploitation is still limited, and projections show a modest growth that may not even match the increase in electricity and general energy consumption. Also, a predominant focus in the existing studies on Kenya is on the potential of PV as a source of renewable energy from a technical perspective and with a particular focus on stand-alone applications. While other countries—especially more economically developed—already target an increased PV exploitation even with poorer solar insulation conditions than Kenya, the country is still lagging behind in this respect. To exploit the potential more thoroughly, there is need for proper analysis of the opportunities and barriers for integration of PV in Kenya's electricity generation mix. The scope of this paper is therefore to analyse the potentials and barriers for deployment of PV technology in Kenya's electricity generation mix.

The paper is based on a review of the existing knowledge within the field, which is subsequently synthesized to provide a multifaceted perspective on opportunities and barriers to grid-connected PV in Kenya. The paper does not investigate off-grid PV systems.
