What is Solar Off grid system and Who can be install?

Solar Off grid system and the usage 

What is Off Grid solar system?

Off-grid systems work independently of the grid but have batteries which can store the solar power generated by the system. The system usually consists of solar panels, battery, charge controller,  inverter or hybrid inverter  mounting structure and balance of systems..

 How it works?

In an off-grid system there is no public electricity grid. Once solar power is used by the appliances in your property, any excess power will be sent to your battery bank. ... When your solar system is not working (night time or cloudy days), your appliances will draw power from the batteries,

The following are the major component of solar off grid system

Major Parts of Solar Off grid system:

1. Solar PV panels
2. DC cables
3. Connector
4. DC MCB
5. Battery
6. Inverter

1. Solar PV Panels: Solar PV panel generally 3 types are available in market

         a, Mono Crystalline panels:

A     mono crystalline solar panel is a solar panel comprising mono crystalline solar cells. These cells are made from a cylindrical silicon ingot grown from a single crystal of silicon of high purity in the same way as a semiconductor. The cylindrical ingot is sliced into wafers forming cells. To maximize the utility of the cells, the circular wafers are wire cut to an octagonal shaped wafer. These cells have a unique look because of the octagonal shape. These cells also have a uniform color.

 The efficiency of mono crystalline panel generally : 17-20%

     Temperature tolerance                                            : -20 to +70 deg C

     Out put in life time (25 years)                                 : 75 to 85 %

      Durability                                                               :510 to 612 Kg/cm2

                                                      : 

b,      b, Poly Crystalline Panels

         c, Thin film solar Panels

Difference Mono crystalline solar panels and poly crystalline solar panels: 

Mono crystalline solar panels have solar cells made from a single crystal of silicon, while poly crystalline solar panels have solar cells made from many silicon fragments melted together.

 

	Mono crystalline solar panels	Poly crystalline solar panels
Cost	More expensive	Less expensive
Efficiency	More efficient	Less efficient
Aesthetics	Solar cells are a black hue	Solar cells have a blue-ish hue
Longevity	25+ years	25+ years

The Pros and Cons of Mono crystalline Solar Panels

While they are the most efficient solar cell on the market, there are several advantages and disadvantages that come with Mono crystalline solar panels, each of which is listed below.

Here are some of the advantages of Mono crystalline solar cells:

Ø  They have the highest level of efficiency at 15-20%

Ø  They require less space compared to other types due to their high efficiency

Ø  Manufacturers state that this form of solar cell lasts the longest, with most giving them a 25-year warranty

Ø  They perform better in low levels of sunlight, making them ideal for cloudy areas

 

Here are some of the disadvantages to Mono crystalline solar cells:

Ø  They are the most expensive solar cells on the market, and so not in everyone’s price range

Ø  The performance levels tend to suffer from an increase in temperature. However, it is a small loss when compared to other forms of solar cell

Ø  There is a lot of waste material when the silicon is cut during manufacture

 DC MCB DC circuit breaker,

like their name suggests, is used for the protection of electrical devices that operate with direct current. The main difference between direct current and alternating current is that in DC the voltage output is constant, while in AC it cycles several times per second.

 

 

 

Differences between DC Circuit Breaker and AC Circuit Breaker

DC and AC circuit breakers work with different types of electric current. As explained above, direct current produces a voltage output that has a constant value over time, while alternating current cycles between positive and negative voltage multiple times per second. The number of cycles per second for alternating current is standardized for every country, and it is 60 hertz or 50 hertz in the majority of cases. Electric grids normally provide AC power, while specialized industrial or battery based applications tend to work with DC power. The following graph illustrates the difference in behavior between an AC voltage supply and a DC voltage supply:

Neither type of electric supply is “better” than the other, and each one is suitable for different types of applications: AC is ideal for generation, long distance power transmission and operation of high power motor devices; while DC is more practical when working with batteries, solar power installations or precision machinery that is easier to control with direct current. Lighting is very versatile, and sometimes different versions of the same lamp are available for direct current and alternating current. DC circuit breakers are frequently used in applications such as:

• Battery powered electric circuits, such as those found in homes with solar panels. Battery powered circuits are also found in homes located in rural zones without an electric grid.
• Electrical components of vehicles, which are present in both gas cars and electric cars. Every car has a fuse box with DC circuit breakers.
• Charging stations for electric vehicles.
• Uninterruptible Power Supply (UPS) systems, which typically uses batteries. Even if the UPS supplies power for AC devices, it must store energy as DC in the battery bank.
• Photovoltaic solar panel installations, their control system and their battery banks.
• Direct current electric motors.
• Some types of electric arc welding machines.
• High efficiency LED lamps.

A very important difference when interrupting alternating current and direct current is that the arc extinguishing point is higher for a DC circuit breaker. In direct current where voltage is continuous, the electric arc is constant and more resistant to interruption. For this reason, DC circuit breakers must include additional arc extinguishing measures: they typically have a mechanism to elongate and dissipate the electric arc in order to simplify interruption. In AC circuit breakers, arc interruption is simpler because the current is alternating and has values of zero in every cycle where it is easier to interrupt.

How Does a DC Circuit Breaker Work? 

DC circuit breakers work with the same principle of thermal protection and magnetic protection which is found in AC circuit breakers:

• Thermal protection trips the DC circuit breaker when electric current above the rated value is present. This protection mechanism is based on a bimetallic contact that heats, expands and trips the circuit breaker. The thermal protection works faster as the current grows larger because more heat is generated to expand and open the electric contact. Thermal protection in a DC circuit breaker protects against overload current, which is only slightly larger than normal operating current.
• Magnetic protection trips the DC circuit breaker when high fault currents are present, and the response is always instantaneous. DC circuit breakers have a rated breaking capacity that represents the maximum fault current that can be interrupted, just like AC circuit breakers. An important consideration with DC circuit breakers is that the current being interrupted is constant, so the circuit breaker must open the electric contact further in order to interrupt the fault current. Magnetic protection in a DC circuit breaker protects against short circuits and faults, which are drastically larger than an overload.

Since the protection mechanism is virtually the same for AC and DC, some models of circuit breakers are designed to work with either type of current. However, it is always very important to verify that the current type of the electric supply and the circuit breaker are the same. If a circuit breaker of the wrong type is installed, it will not be able to protect the installation effectively and electric accidents might occur!

Another important consideration is that the electric wiring connecting the DC circuit breaker and the electric device being protected must have an adequate rated current. Even if the DC circuit breaker is selected correctly, an undersized cable can overheat, melting its insulation and causing an electric fault.

Just like AC circuit breakers, DC circuit breakers are also available in miniature version and molded case version:

• Miniature DC circuit breakers typically work with currents below 100 amperes and they are classified into Type B (trips at 3-5 times rated current), type C (trips at 5-10 times rated current) and type D (trips at 10-20 times rated current).
• Molded case circuit breakers are larger and typically have adjustable protection settings.

DC Circuit Breaker Wiring and Installation

DC circuit breakers are installed in fuse boxes that have a rail specially designed for them. They can be used to protect individual loads that work with direct current, or they can be used to protect main circuits such as those of inverters, solar PV arrays, or battery banks. The physical installation of DC circuit breakers has many similarities to AC circuit breaker:

• Direct current circuits will be connected to a fuse box and the cable will typically be protected by an adequate plastic or metallic duct.
• The circuit can be connected directly to the direct current device and controlled with a switch, or it can be a plug-in electric outlet.
• Direct current circuit breakers are connected in series with the live conductor for each individual circuit.

However, DC circuit breaker wiring is simpler than in AC circuit breakers. This is because AC current can have up to three different live conductors, but DC current only has one. In alternating current, each live conductor must be connected to the correct pole of the circuit breaker. Errors in connection can cause electric accidents or make motors to run in the opposite direction. With direct current, on the other hand, all applications work with just one live conductor and there is no risk of confusing connections.

DC circuit breaker installation is very important if the user has a solar PV system. It requires protection at several points:

• Solar PV panels are connected in series circuits, and one installation may have one or more circuits depending on its capacity. All of the circuits are connected to a PV combiner box, where each is protected by a DC circuit breaker. Protecting the solar panel circuits is critical, since they are the most expensive part of the system.
• Once the power supplied by all solar panels is combined into a single direct current output, a main DC circuit breaker will be needed.
• If the system uses a battery bank, it must also be protected by a DC circuit breaker.
• The inverter, which converts direct current to alternating current, requires a DC circuit breaker at the source.
• Finally, if the user has an exclusive electric panel for DC loads, an array of DC circuit breakers will be required.

DC Circuit Breaker Used in Solar Power

Renewable energy technologies are starting to gain importance in the world and are expected to become mainstream over the course of this century. Some of these technologies, such as photovoltaic solar panels and electric vehicles, work with direct current and use DC circuit breakers for electric protection. These technologies tend to be very expensive, so it is critical to use DC circuit breakers to ensure a long service life and a return on the investment.

Photovoltaic solar panels convert solar irradiation into direct current, which can then be used to power electric devices. It is very important to protect solar panels with DC circuit breakers because even a small photovoltaic installation can cost several thousand dollars.

When a home user owns solar panels, he or she has the option of using both DC and AC electrical devices. For example, homeowners who have solar panels can purchase direct current LED lamps. In these cases, DC circuit breakers must be used for protection. The rest of the DC power can be converted to AC with an electric inverter. Homeowners who have several direct current circuits install separate fuse boxes for direct current and alternating current, each with several circuit breakers.

Electric vehicles, like their name implies, are completely independent of fossil fuels and instead work with a high capacity rechargeable battery. These batteries in turn work with charging stations that are specially designed for electric vehicles. Since this system works completely with direct current, it must use DC circuit breakers. It is very common for photovoltaic solar panels and electric vehicle charging stations to work together, since the entire system works with direct current and conversion to alternating current is not necessary to charge an electric vehicle. This system provides a completely eco-friendly and sustainable energy source for transportation.

 3) What is Charge Controller?

A solar charge controller manages the power going into the battery bank from the solar array.  It ensures that the deep cycle batteries are not overcharged during the day, and that the power doesn’t run backwards to the solar panels overnight and drain the batteries. Some charge controllers are available with additional capabilities, like lighting and load control, but managing the power is its primary job.

  Two type of charge controller are available in market

a)      PWM: Pulse Width Modulation  is the most effective means to achieve constant voltage battery charging by switching the solar system controller's power devices. When in PWM regulation, the current from the solar array tapers according to the battery's condition and recharging needs.

b)     MPPT:  Maximum Power Point Tracking is algorithm that included in charge controllers used for extracting maximum available power from PV module under certain conditions. The voltage at which PV module can produce maximum power is called maximum power point (or peak power voltage).

 

PWM Type Solar Controllers	MPPT Solar Controllers
PROS
– PWM controllers are built on a time tested technology. They have been used for years in Solar systems, and are well established – These controllers are inexpensive – PWM controllers are available in sizes up to 60 Amps – PWM controllers are durable, most with passive heat sink style cooling – These controllers are available in many sizes for a variety of applications	– MPPT controllers offer a potential increase in charging efficiency up to 30% – These controllers also offer the potential ability to have an array with higher input voltage than the battery bank – You can get sizes up to 80 Amps – MPPT controller warranties are typically longer than PWM units – MPPT offer great flexibility for system growth – MPPT is the only way to regulate grid connect modules for battery charging
CONS
– The Solar input nominal voltage must match the battery bank nominal voltage if you’re going to use PWM – There is no single controller sized over 60 amps DC as of yet – Many smaller PWM controller units are not UL listed – Many smaller PWM controller units come without fittings for conduit – PWM controllers have limited capacity for system growth – Can’t be used on higher voltage grid connect modules	– MPPT controllers are more expensive, sometimes costing twice as much as a PWM controller – MPPT units are generally larger in physical size – Sizing an appropriate Solar array can be challenging without MPPT controller manufacturer guides – Using an MPPT controller forces the Solar array to be comprised of like photovoltaic modules in like strings

4)    Battery: What is Battery?

A connected group of (one or more) electro chemical cells that store electric charges and generate direct current (DC) through the conversion of chemical energy into electrical energy. See also common battery, DC, electricity, energy, and local battery.

M/s PMM Smart Future solution – Ranipet – Supplying solar Off grid system from 0.180 KW to 10KW to home and commercial application with India’s No. 1 Premium brand loom Solar Mono Crystalline panels

Source from 

https://www.loomsolar.com/collections/off-grid-solar-system