Simulation of Photovoltaic Power System for Rural Electrification in Myanmar

. In the recent years substantial growth of the demand for electricity took place in Myanmar; energy generation by existing sources (mainly hydropower) is not enough to provide constantly increasing consumption. The problem is most obvious in rural areas (more than 61 percent of the population) where grid extension is not justi ﬁ ed economically whereas the cost of electricity produced by autonomous diesel generators is extremely high. ( Research purpose ) The purpose of this research is the evaluation of economic and technical feasibility of small o ﬀ -grid (standalone) photovoltaic (PV only) and hybrid photovoltaic-diesel (PV-diesel) power generation systems providing rural household electricity consumption in Myanmar. ( Materials and methods ) Computer simulation using Homer pro simulation software was used. Three di ﬀ erent load scenarios were envisaged – low, medium and high (1; 6 and 16 kilowatt-hour per day). Simulation was done for Tha Ngar village tract with a population of about 3,000 people, which is typical in Myanmar. ( Results and discussion ) The results of the simulation reveal that the levelized cost of energy (LCOE) for optimal hybrid (PV-diesel) systems lies in the range 0.37-0.51 US$, for PV only systems – 0.46-0.49 US$. It proves their economic feasibility compared to conventional diesel generator systems with LCOE 0.56-1.56 US$ boosted by high fuel prices in remote areas (2-3 times higher than urban price). For the high load scenario hybrid systems are more preferable, for low load (night time lighting only) PV only systems may be more e ﬀ ective. ( Conclusions ) It can be concluded that implementing solar energy is not only environmentally friendlier but also economically justi ﬁ ed approach for providing household electricity demands of rural settlements in Myanmar without constructing expensive grid extensions.

M yanmar, one of the Southeast Asian Nations is located between latitudes 09º32′ N and 28º31′ N and longitudes 92º10′ E and 101º11′ E with an area of 677,000 square kilometers with population over 52 million which expected to grow to 64 million, while the average per capita electricity demand rises from 0.3 to 0.7 MWh before 2050 [1]. Electricity demand of the country has been increasing every year especially in rural area. Therefore, almost all possible energy sources should be considered for Myanmar. Myanmar electricity production capacity is only around 3000 MW which depends mainly on hydropower. Natural gas, coal and other energy sources are also used.
Rural electrification become a major problem for Myanmar [2]. According to the data of Ministry of Electricity and Energy, 2020, only 50% of total households in Myanmar have access to electricity and most of them are located in urban area. In Myanmar, 70% of total population lives in rural area so electricity access to them is very important [3]. Moreover, 61% of the country population lives in village tracts whose have a population just between 1000 and 10000 and approximately 10346 (76%) of total 13620 villages tracts have that kind of population ( Table 1).

State / Region
According to the map (Fig. 1), the average yearly total of specific PV power production varies between 1150 kWh/kWp (equals to average daily total of about 3.2 kWh/kWp) and 1600 kWh/kWp (about 4.4 kWh/kWp daily) with high values in the central region ( Fig. 1). In mountains, the power production is lower by up to 20% or even more, due to terrain shading (Suri M. et al., 2017).
According to the national electrification plan, PV will also be one of the important energy sources in Myanmar. It is aimed to reach 5% of total electricity production in 2030. First Myanmar PV solar power plant, 170 MW will start production in summer, 2020.
RESEARCH PURPOSE is the evaluation of economic and technical feasibility of small off-grid (standalone) photovoltaic (PV only) and hybrid photovoltaic-diesel (PV-diesel) power generation systems providing rural household electricity consumption in Myanmar.

MATERIALS AND METHODS.
In applying solar energy system in rural area, there are lots of things have to be considered to predict the economic feasibility of PV installations. The best way to make such predictions is preliminary computer simulations with dedicated software tools (Homer pro, RETscreen, etc.) [6,7]. We evaluated economic and technical feasibility of off-grid (standalone) PV systems for a Village Tract of Myanmar called Tha Ngar using Homer pro software. Its location is 23°58'25.0" N 94°36'24.5" E. It has population of 2959 living in 439 households. Tha Ngar is 10 km away from the nearest road and 68 km away from grid which will make it to be the last priority in national electrification plan.
For simulation we used climate data provided by NASA. Daily solar radiation ranged from 3.7 to 5.6 kWh/m 2 /d. Wind speed was between 0.8 and 1.2 m/s (Fig. 2). Relative humidity was min 39% and max 66%. Air temperature was minimum 17°C in January and maximum 28.9°C in June.
Three different load scenarios which match the real needs and situations of rural area of Myanmar were prepared (Tables 2-4).

ЭКОЛОГИЯ ECOLOGY
Low consumption (LC) is night only lighting purpose, generally from 4 to 7 am and 6 to 9 pm ( Table 2). Total daily consumption is around 1.092 kWh/day. In most rural village, the minimum load hours can be reduced to 6 hours daily. In village life, it is still "early to bed and early to rise". They wake up before 4 am and prepare for their work. So, this period is important for them to get light. Medium consumption (MC) aims for more than lighting purpose but still prefer small load. Load is 6.036 kWh/day ( Table 3). High consumption (HC) will be functional household usage with 16.206 kWh/day ( Table 4). But it still can be said not much load comparing to urban usage.
These scenarios are flexible and can be change depending on regions and needs. These load scenarios were calculated based on information taken from some research and surveys in Myanmar (Myint A.K., Ya A.Z., Ohn S.S., Aung S.M., 2018).
Using Homer pro, assessment tool for hybrid renewable electric generation systems, analyzing was done. Two systems, PV only and Hybrid (PV-Diesel), were compared for each scenario. Generally, a PV system should have some backup generation because there are certain conditions when PV generation can be unavailable (due to weather, maintenance etc.). But here it was simulated without a backup generator in order to compare costs for PV only and Hybrid systems. Moreover, in some cases, such as LC, where load is very small and only aim for lighting purpose thus it is also possible not to use backups like a diesel generator.
Moreover, it is important to apply best parameters; system components and design, their costs and efficiency which have to be similar to the real costs on the local market (in this case, Myanmar). Depending on the input data, the simulation results can be different, but they were always rechecked by comparing with other external data.
RESULTS AND DISCUSSION. In total six possible system options, two different types (PV only and hybrid) for each load consumption scenario were simulated.
The system architecture requires to meet three load scenarios (LC, MC, and HC) in the most optimal way ( Table 5). More solar panels were needed in the PV only system. It was also possible to reduce the number of solar panels that we used in Hybrid systems just by increasing time of using diesel generator when fuel price become lower and advantage was that it was no need to increase diesel generator system capacity (same generators). As maximum, 8.5 kW PV panels were needed to cover total usage of 16 kWh/day in HC scenario of PV only system.
Even in the hybrid system, diesel generator output should be lower than PV output of that system in order to get lower costs for high fuel price. Simulation result recommended less diesel usage even in hybrid system because of its cost (initial cost, fuel cost). This is because generally, in rural area of Myanmar the fuel cost always more than the urban price. In places where transportation conditions are very bad, the fuel price usually can be double or even triple of urban price.
We can see effects of fuel price and nominal discount rate (Fig. 3). Lower nominal rate and higher fuel price made PV system more desirable. At many rural places of Myanmar, the fuel cost is more than urban price. Therefore, PV system will be more preferable for rural area including this village.
Another important fact to be considered was levelized cost of energy (LCOE). This indicator shows range from 0.369 US$ to 0.511 US$ for the Hybrid system and range from 0.46 US$ to 0.49 US$ for the PV only system (Fig. 4). Both systems have better LCOE than "diesel only" system which was still more expensive even at the urban fuel price. The price of fuel in this villages was 1.34 $/L which was double of the urban price. This price also depended on many factors such as difficult transportation, importing components, etc. Other than that, one important fact was energy storage cost.

ЭКОЛОГИЯ ECOLOGY
In Myanmar, lead acid batteries are still being used as energy storage for PV system despite the fact that they are expensive and have some failures such as voltage drops, very short life (sometimes less than 20 months) [3]. The price in this simulation is 180 US$/kWh with replacement cost 145 US$/kWh. But now it is recommended to use lithium-ion batteries which have more life time and better quality than lead acid and whose price has been falling (in 2020, the price estimated to drop around 124.24 US$/kWh). This will definitely have positive effect on LCOE. With reducing battery and PV cost LCOE of PV can reach around 0.2 US$ per kWh or even lower.
Net present cost of all PV only scenarios were cheaper than that of Hybrid systems because of high fuel price in rural areas while initial cost of Hybrid systems was cheaper than PV only except LC scenario (Fig. 5). Overall, we can conclude that PV systems (both PV only and Hybrid) are cost effective and could be implemented as an economically justified solution for electrification of rural area in Myanmar.
For further alternative ways related to PV although not analyzed in this paper, there are also good potential for other solar hybrid systems (solar + wind, solar + biomass) [8]. As reported by Asian development bank, not only offgrid system but also mini-grid and on-grid system may be considered [9,10].
CONCLUSION. According to the simulation results, PV only systems are a little more expensive than hybrid systems in terms of initial cost. Initial cost for three scena-rios of PV only are 1118 $, 5794 $, and 15882 $ while those of hybrid are 1135 $, 4847 $, and 14909 $ respectively. We should also be aware that initial cost of hybrid does not include the cost of fuel that will be consumed in total system life time. Both PV only and Hybrid costs are almost the same because the amount of PV panels used in both systems also almost the same. PV only may be a little cheaper than Hybrid but Hybrid has an advantage that it can be more reliable. For example, some unexpected days where PV output largely decrease due to weather. But both systems were surely better than ones depending only on diesel generators.
Because in this research only one location has been considered, it was difficult to cover details of all rural areas in Myanmar. But most fundamentals and backgrounds are similar so that we can adopt this for considering other villages or rural settlements of Myanmar in future. Moreover, in rural electrification, it can be implemented not only for household usage but also for others such as worship places (pagodas, monasteries), educational institutions (mainly primary schools), small businesses, agriculture related usage (irrigation) etc. Almost all villages in Myanmar have above places at least one or more and they also need electricity.
PV systems can be recommended as one of the reliable energy sources of Myanmar and other regions with close climatic and socio-economic conditions. It will be more suitable in future because of price falling and technologies development.

Acknowledgement Special thanks to Dmitriy Bogdanov and Christian
Breyer for allowing us to use presentation "Global 100% RE System: Southeast Asia -Myanmar".