The History of Using Solar Energy Loránd Szabó Department of Electrical Machines and Drives Technical University of Cluj-Napoca Cluj-Napoca, Romania e-mail: Lorand.Szabo@emd.utcluj.ro Abstract—The energy received on Earth from the Sun is plentiful and totally renewable. Basically, the sun enabled life on our planet, and our life cannot be imagined without it. The sun is directly or indirectly at the origin for nearly all the energy resources on Earth, as fossil fuels (coal, natural gas and oil), hydro (global water circulation is due to the sun), wind, waves, biomass, etc. The sunlight was used as an energy resource already by ancient civilizations. Since than a lot of innovative technologies and advancements were performed in this field. The paper presents the main milestones of the developments performed in this important field of energy conversion. Keywords—solar energy; science history. I. INTRODUCTION The energy requirement of the mankind is continuously growing. It is forecasted that by the middle of our century the global energy demand will at least double. This huge energy necessity and the actual environmental challenges will be possible to be covered by the increasing electrical energy conversion from renewables, among them solar energy [1]. The annual solar energy potential of the Earth is 23,000 TWy. 1,600 TWy should be the world energy consumption for 100 years (computed with the yearly consumption in 2009), as it is illustrated in Fig. 1. For comparison, the Earth's total finite energy resources (coal, uranium, petroleum and natural gas) are of 1,655 TWy and the most optimist estimations of the energy that can be converted yearly from non-solar renewable resources (wind, ocean, biomass, hydro and geothermal) is only 94 TWy [2]. Fig. 1 The solar potential vs. energy consumption Almost all the energy forms used in electrical power generation are of solar origin. Oil, coal, natural gas and woods were originally produced by means of photosynthesis. Wind and waves are due to temperature differences [3], [4], [5]. Throughout the history, each new applied energy form contributed to the development of the society [6]. The use of the very clean solar energy is not a new discovery of the scientist of our days. It was used in diverse scopes since a lot of centuries. Therefore, the history of solar energy conversion is long, various and exciting. The paper will deal with the most important and interesting milestones of the developments performed in this field of energy conversion. II. ANCIENT AGES The sun has a vital role in the life on Earth. This was recognized and celebrated by all the cultures already in the ancient ages. Peoples of those days admired the Sun, and even frequently personified and worshipped it as a deity [7]. Egyptian pharaoh Akhenaten IV (1353 BC - 1336 BC), husband of the more famous Nefertiti queen, forced religious reforms concerning monotheistic state religion instead of traditional polytheism religious conviction of the ancient Egyptians. He deified himself as a god, who alone could worship Aten, the single god accepted that time. Aten was the sun disk in the Egyptian mythology, and originally an aspect of the god Ra, the Egyptians' sun god. The contact with Aten was possible through the sunrays, as shown in Fig. 2 [8]. Fig. 2 Pharaoh Akhenaten IV in the sunrays being in contact with Aten This work was supported by the Romanian Executive Agency for Higher Education, Research, Development and Innovation Funding (UEFISCDI) via SWTOMP ERANet-LAC project no. 21/2017. 978-1-5090-6565-3/17/$31.00 ©2017 IEEE The 7th International Conference on Modern Power Systems (MPS 2017)