Construction of a Mini off Grid Solar Home System



The off-grid system term states the system not relating to the gird facility. Primarily, the system which is not connected to the main electrical grid is term as off-grid PV system . Off-grid system also called standalone system or mini grid which can generate the power and run the appliances by itself. Off-grid systems are suitable for the electrification of small community. Off-grid electrification system is viable for the remote areas in the countries where they do have little or no access to the electricity because of the distinct living and spread population in the vast area. The off-grid system refers to the support that would be adequate for a living without depending on the grid or other system. Electrical energy in the off-gird system produced through the Solar photovoltaic panels needs to be stored or saved because requirement from the load can be different from the solar panel output, battery bank is also used for the purpose generally.

1.1 Background of study

Energy systems often include Renewables Energy Systems (RES). RES play an important role from technical, economic, social and environmental point of view. The high cost of the fuel used in systems based totally on diesel generators (gensets) has led to the development of hybrid energy systems. Hybrid energy systems are the combination of two or more energy sources, from Renewable Energy Technologies (RETs) and from conventional technologies, with an energy storage and power conditioning system. The use of RES would reduce the fuel consumption as well as the polluted emission of a 100% diesel plant. The initial investment will be higher in a hybrid energy system, but the use of fuel and consequently its cost will be reduced.

1.2 Statement of the problem

About 1.3 billion people worldwide have no access to electricity. Around 20 % of the total population, most of them located in rural or isolated areas have little or no access to main grid. A good development of Mini Grid systems, apart from offering reliable electricity, could also improve the economy of these areas. On the other hand, climate change implies finding new ways to obtain energy and protect the environment, renewable energy systems are escalating fast, and can lead to fight carbondioxide(CO2) emissions in a high percentage. Three important fields to consider in this study will be technical, economic and social aspects, which have to be taken into account when choosing a Mini off-Grid system implementation. Regarding the technological dimension, significant advances can be observed with these kinds of technologies. Secondly, there is a need for an affordable operation and durable system installation. Thirdly, with respect to the social dimension, a lack of communication exists between foreign companies that install the components taking part in mini-grid systems, and the locals that live in rural or isolated areas and own the land. In addition, there are some constraints when evaluating the success of the whole system installation and its performance. For instance, referring to PV and wind turbines, it is known that they do not always work at their maximum production level, since it will always depend on the daily sun radiation and wind speed. This situation could lead, in some cases, to an overuse of the diesel generator implying greater economic expenses and higher emissions. Moreover, another disadvantage related to the installation process is the difficulties that can be found in reaching isolated areas due to the existence of poor access, for example, for transportation. In summary, the current study is relevant principally to provide these communities and areas with reliable electrification; consequently, implying an improvement in their lifestyle and economy. Therefore, this document tries to explore the crucially important position of households in Mini off-Grid systems in order to achieve a better understanding and a more encompassing policy debate while taking into account the proper and most efficient use of natural resources.

1.3 Aim and Objectives of the Research:

The usage of solar energy is increasing day by day both in terms of demand and usage. Our aim is to provide the most useful solar solution while maintaining the novelty. So, the construction of a mini off-grid solar home system. Futhermore, An off grid system with DC load along battery bank. The off-grid application is considered because the system is to be independent of the grid so that it can be used at any time.
The objective of this research is to provide a better understanding of the different kind of impacts the use of off-grid solar systems has upon the livelihoods of households

1.4 Contribution to knowledge

The construction of a mini off grid solar system has brought about the understanding that life can be made a lot easier with the presence of a mini off grid solar system as sun is free, sustainable, clean resources we can leverage in place of convectional electricity to power our lives. Solar energy can be used to provide heat, light and other electricity-dependent needs in homes

1.5 limitation/scope of the project

Some of the limitations of an off grid mini home solar system include;

  • They are more costly
  • batteries are required to deliver electricity consistently throughout the day and night
  • it could require a lifestyle change to reduce energy consumption
  • surplus energy production
  • cannot rely on the grid at night or on cloudy days
  • batteries require maintenance, have a relatively short lifespan and degrade rapidly


2.1 Brief outline of the project

2.2 Historical background of the project

The term off grid first appeared in the mid nineties, highlighted by the environmental nick Rosen in the launch of an ecological motivated website www.offgrid,net and featured more recently in his book how to live off grid (Doubleday 2007)
The history of solar energy
Thinking of solar energy in the 21st century,a smart system of powering our homes with the light from the sun and solar panels. While solar panel technology is relatively new, dating back about 50 years, the use of suns energy to sustain livelihoods in fact began a number of centuries ago.
History with the sun has a far dating and fascinating history, documented from as far as the 7th century B.C . Societies, throughout time, have been using the suns energy in intelligent ways to facilitate their lives. From the discovery of fire to the vast commercialization of solar power and domestic usage in todays world.
The solar energy we have known to come and love as a renewable form of energy, has inspired some of the greatest changes in recent times . Below is the summarization of the solar energy breakthroughs from the 16th century to the present day
Ancient uses of solar energy
Early uses of the sun focused on harnessing the sun’s energy for use as a heat source. Dating back to the Ancient Egyptian civilizations, buildings were designed in ways that maximized light entry and warmth.
From the 3rd Century B.C., the Ancient Greeks and Romans were using sunlight to create fire torches. Proving particularly handy for sacred and religious ceremonies.

The 16th-17th century: Development of the first solar cell
Fast forward to the 16th century, the first solar cell was designed by Swiss Scientist Horace-Benedict de Saussure in 1767.
Seventy-two years later, further innovation and progress in the evolution of solar energy was made. At just 19 years old, French scientist Edmond Becqurel discovered the Photovoltaic Effect: voltage and electric current in materials can be generated upon exposure to light.
By 1870, another milestone was reached where the discovery that light could be turned into electricity without heat is made.
Moving onto the 1890s, the first commercial solar heat pump was patented.
By the end of the 17th century, American inventor Charles Fritz created the first working selenium solar cell (in today’s era, silicon is used in cells for solar panels).
Up until this point, the contribution and experimental discoveries of various inventors and scientists had led up to the creation of the modern solar photovoltaic (PV) panel.

Early 20th Century: The modenization of solar energy
1905 was the year a young Albert Einstein (26 years old at the time) published his work titled “On a Heuristic Viewpoint Concerning the Production and Transformation of Light.” Where he studied what became known as the photoelectric effect.
1917 Einstein gave a theoretical foundation to photovoltaics by introducing the notion that lights as packets carry electromagnetic force.
By 1954, scientists at Bell Laboratories developed the first practical photovoltaic cell.
By the mid 1950s the first solar-powered telephone call was made. Illustrating the further development and reliability in solar energy being recognised.
A year later in 1956, the first solar powered radio was introduced by General Electric. The radio was able to function in the day and night.
Just a few years later, the US experimented with the application of solar PV cells on Earth orbiting satellites. Since then and up to the present day, solar power is the accepted energy source for space applications!
By 1958 a spacecraft called Vanguard I became the first to be powered by solar panels.
In London 1960, the first solar car was introduced, with a solar-panel roof and a 72-volt battery.
1982 was when the first large-scale solar farm was built near Hesperia, California.
Developments in solar continued throughout the 1990s, and emerging global economies began to grow their share in renewables (especially wind and solar PV) during this time.
The 2000s: Solar energy goes commercial
From the 2000s, solar power starts to become accessible for everyone. The renewable energy sector is booming and the following decade sees ground-breaking advancements and the expansion in solar PV tech and their installations respectively.
Mandatory targets for renewable energy are now set across the EU.
We see the development of a competitive internal energy market, with renewables playing an important role.
From the 2000s to the 2010s, more capacity is added to the renewables sector than any other (and this trend is continuing!).
In 2012, the European Photovoltaic Industry Association, stated that ‘the solar PV industry installed more than 30 gigawatts worldwide which led to the cumulative global installations to be more than 100 gigawatts.’
Solar panels become more efficient, convenient and easier to access for home and business owners. As of 2018, there were more than 1 million solar PV installations.
During 2018, the UK generated 3.9% of its total electricity using solar power.
2019 saw the first offshore floating solar farm is installed in the Dutch North Sea.
By 2020 it was cheaper to build a new solar plant than it is to continue operating an existing coal plant. Showing just the extent of our reliance on solar energy.
By 2020 The International Energy Agency declared that “Solar is the new king of the electricity markets”.
And finally, 2021 and 2022 is set to see renewable energy accounting for 90% of new power capacity expansion globally.
The present day: Solar energy goes global
Today, we continue to see the expansion and use of solar powered devices, infrastructure and transport. Investments into solar parks and farms (both the small and mega) continue to take place across the globe.
The historic advancements and current position of solar place the power of this renewable resource in a promising position. In terms of the UK’s solar future, it looks particularly bright as it sets to double its solar capacity by 2030.

2.3 Theory and concept revelant to the study

ITEMPOWER (W)QTY (n)Number of hoursEnergy Wh
Solar panel50190.450
Total power330630309wh = 3.09Kwh
BEME Table 2.3 Theory and concept revelant to the study

2.3.2 Shade Analysis: Shading can be a problem for the solar panels as they decrease the maximum power that can be generated. Several factors contribute to this issue, the most common cause of shade on a solar panel are;

1) Shade from neighboring trees and buildings in vicinity,

2) typical cloudy weather, and

3) shade from adjacent solar panels.

While designing a solar PV system one must investigate these factors thoroughly so that maximum output can be obtained. One of the tools most commonly used is solar pathfinder which gives the direction of the sun throughout the year and how much any specific area will receive sunlight throughout the year. Apart from having this tool, it is important that the site assessment is done properly to locate the best site keeping in mind all the aspects.
Sun hours: Sun hours are important to know how much radiance will be required to generate the needed output wattage. This parameter gives us the knowledge of number of hours an area will receive maximum sunlight. With advances in technology we have this data available online and anyone can use it. We have studied the data from NREL and NASA but for our project we will be uvsing data given by NREL as it is giving information of the Sun hours to a closer proximity to Charleston. The following chart gives the required information of the Sun hours depending on different zones classified by NREL
chart 2.2 Sun hours depending on different time zones

Sun hours depending on different time zones
Sun hours depending on different time zones

Tilt angle: Tilt angle is the setting of the panels one needs to have to get the maximum radiance. Ideally the tilt angle is the latitude of the geographic location. It is suggested to have an adjustable panel frames as the sun hours keep changing with respect to the tilt in winters and summers. Hence for any area a specaific tilt angle is calculated to get the maximum radiance throughout the year for a fixed panel. Also, it is advised to have the panels facing the south to get the maximum afternoon sun. A couple of devices are used in the process of finding the tilt angle and the radiance that will fall upon panel at that tilt angle are inclinometer and pyrometer, respectively. An inclinometer is kept on the panel and the degrees are read to find the latitude of the area as it is perpendicular to the Sun’s radiations when it is at its highest point in the sky. Pyrometer measures the solar irradiance that will fall at a given tilt angle. It measures solar irradiance in Watts per meter Sq.
2.3.3 Battery Sizing;
PV battery system assesses various strategies from a financial perspective. The valuable existence of the battery is limited to 5,000 cycles or in the planned living time of 20 years. The maintenance of photovoltaic and rechargeable annual activities and expenditure systems is set at 1.5% per the speculative cost. Assume that the cost system for the battery and PV is comparable to their size. Following is a formula that will enable to calculate what size of battery they should have. (Leonics, n.d.) Battery Capacity (Ah) = Total Watt-hours per day used by appliances x Days of autonomy (0.85 x 0.6 x nominal battery voltage)
2.3.4 Inverter: Inverter deals with following main tasks of energy: (ALTE store, n.d.)
Convert DC from PV module to AC
Ensure that the cycle of alternating current cycles is 60 cycles
Reduce voltage variations
Ensure that the condition of the AC waveform is suitable for the application
Most system-connected inverters can be introduced externally, and most of the off-grid inverters are not weather-resistant. There are basically two types of grid intelligent Inverters: Those designed for batteries and those designed for systems without battery-connected inverter systems and give excellent void-quality strength. For matrix associations, the inverter should have a “useful-interactive” typeface, which is printed specifically for the publication name.
Grid-connected systems measure the power of extracting PV clusters rather than a bunch of prerequisite buildings. It asserts that what each power supply needs are what the matrix-related PV system can give naturally is drawn from the net. Invertors used for solar PV systems are usually based upon the total wattage of the solar panels, as the invertor will be continuously converting the power generated. The second consideration one must investigate, is the voltage level of the system. For example, if the system is designed to generate 2000 Watts at a voltage level of 12 V then the invertor selected should be rated 12V, 2000 Watts (Alternative Energy, n.d.).
2.3.5 Charge Controller: The charge controller, sometimes referred to as a photovoltaic controller or charger, is only necessary for the system which involves a battery (Wholesale Solar, n.d.). The main capacity of the charge controller is to counteract the battery spoofing. The basic function of charge controller is to monitor charging and discharging of the battery. It prevents the battery from being completely charged or discharged. This is important because over charging can lead to destruction of the battery and under charging decreases the battery life. Another important reason to use a charge controller is to prevent a reverse current flowing from battery to the system. There are two types of controllers that are widely available in the market; 1) Pulse width Modulation (PWM), 2) Maximum Power Point Tracking (MPPT) (Northern Arizon Wind and Sun, n.d.) 1. Pulse width modulation: A pulse width modulation charge controller is set match the input power of the battery irrespective of the power generated by the panels. There is an inherent loss in power observed in this type of charger. 2. Maximum Power Point Tracking (MPPT): This type of charger helps to get the optimum charging power for any given point of time and offers better efficiency that PWM. Though the MPPT charge controllers enable you to have better efficiencies and provides more power than compared to PWM for similar condition, the main cause of not opting for MPPT is price of it (Solar Guy, 2016). MPPT charge controllers are more expensive than PWM controllers. Keeping this parameter in mind, this project will be using a PWM charge controller for realizing the concept. To select the size of charge controller one must know the voltage level of the system and the maximum operating current. It is a usual practice to over size the controller for safety reasons. Proposal to Convert 7th Street Bus Stand into a Standalone PV System Bus shelters are common in every structure one can find in urban and sub-urban settings and most of them are tied to the grid to provide electricity. But most of the rural and sub-urban areas do not have this facility of having their bus shelters electrified through grid. In such place we could use the off-grid or standalone PV system which can function without the grids assistance. Eastern Illinois University has always been a leader in embracing new technologies that promotes betterment of the environment and its students. Panther shuttle bus-stops across the campus serve hundreds of the students on a day-to-day basis. Currently, all the bus stops on the campus are not connected with the existing electrical grid. Hence, taking an initiative to serve the students an also realizing a proof of concept for standalone systems the following PV system has been designed.

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