Flow Battery

In off-grid solar technology batteries are the main source of reserved energy after it is been charged by the solar panels.In solar technology there are different types of batteries  available like Lead-acid batteries ,or Lithium-ion batteries or Sodium Nickel Chloride or Flow batteries.In this section we are going to learn  flow batteries.

One of the latest developments in the solar battery storage space are 'flow' batteries (or 'redox flow batteries' if you want to get technical). The fundamental difference between conventional batteries and flow cells is that energy is stored not as the electrode material in conventional batteries but as the electrolyte in flow cells.

A flow battery, or redox flow battery (after reduction–oxidation), is a type of electrochemical cell where chemical energy is provided by two chemical components dissolved in liquids contained within the system and separated by a membrane. Ion exchange (accompanied by flow of electric current) occurs through the membrane while both liquids circulate in their own respective space. Cell voltage is chemically determined by the Nernst equation and ranges, in practical applications, from 1.0 to 2.2 volts.

A flow battery may be used like a fuel cell (where the spent fuel is extracted and new fuel is added to the system) or like a rechargeable battery(where an electric power source drives regeneration of the fuel). While it has technical advantages over conventional rechargeable, such as potentially separable liquid tanks and near unlimited longevity, current implementations are comparatively less powerful and require more sophisticated electronics.


 Types of flow batteries :

Various types of flow cells (batteries) have been developed,including redox, hybrid and membrane less.

•  Redox
•  Hybrid
•  Membrane-less
•  Organic 
•  Metal Hydride
•  Nano-network
•  Semi-solid 

Flow batteries actually describes a number of similar technologies that all fall under the same umbrella, but this page will predominantly discuss the 'ZCell' Zinc-Bromide batteries manufactured in North America by the Australian company RedFlow.

Discussing the science behind flow batteries can get rather technical, so I'll massively simplify it. A flow battery is mostly made up of a water based liquid (Zinc Bromide) that flows between two tanks. When the battery charges the Zinc is extracted from the liquid and stored separately. When discharging, the Zinc is put back into the liquid. The Zinc 'flows' from the big plastic tank at the bottom of the picture to the electrodes at the top.  Hence the name.

One of the core advantages that flow batteries have over lithium-ion and lead-acid batteries is that they have a 100% depth-of-discharge - which means the entire battery can be discharged in a cycle with no negative effects on the lifespan of the battery. For comparison, lead-acid batteries have a 60% depth-of-discharge, and most lithium-ion batteries have an 80-90% depth-of-discharge.

They can also sit on the shelf forever-and-a-day at zero charge without degrading. Again - most other battery technologies need to be kept at a minimum charge level.

There are a number of other benefits that flow batteries offer:

• They can tolerate extreme weather conditions, up to 50 degrees Celsius.
• The zinc-bromine liquid inside the flow batteries is a natural fire retardant. 
• No chance of a thermal runaway (explosion!) due to the physical separation of the different battery components.
• Cheaper to refurbish due to their simple modular construction. For example, you can restore a 'dead' battery by simply swapping the electrode - for half of the original price of the battery.

A disadvantage of flow batteries is their life cycle compared to some higher-end lithium-ion batteries - they have a lifespan of approximately 4000 cycles at 100% depth-of-discharge, which is less than top quality lithium-ion's 5000-6000 cycles at 80% depth-of-discharge.

They also need to regularly be 100% discharged to 'clean' the electrodes. But, the battery management can be programmed to automatically do this regularly.

Applications

Flow batteries are normally considered for relatively large (1 kWh – 10 MWh) stationary applications. These are for

• Load balancing – where the battery is connected to an electrical grid to store excess electrical power during off-peak hours and release electrical power during peak demand periods. The common problem limiting the use of most flow battery chemistries in this application is their low areal power (operating current density) which translates into a high cost of power.
• Storing energy from renewable sources such as wind or solar for discharge during periods of peak demand.
• Peak shaving, where spikes of demand are met by the battery.
• UPS, where the battery is used if the main power fails to provide an uninterrupted supply.
• Power conversion – because all cells share the same electrolyte/s. Therefore, the electrolyte/s may be charged using a given number of cells and discharged with a different number. Because the voltage of the battery is proportional to the number of cells used the battery can therefore act as a very powerful DC–DC converter. In addition, if the number of cells is continuously changed (on the input and/or output side) power conversion can also be AC/DC, AC/AC, or DC–AC with the frequency limited by that of the switching gear.
• Electric vehicles – Because flow batteries can be rapidly "recharged" by replacing the electrolyte, they can be used for applications where the vehicle needs to take on energy as fast as a combustion engined vehicle. A common problem found with most RFB chemistries in the EV applications is their low energy density which translated into a short driving range. Flow batteries based on highly soluble halates are a notable exception.
• Stand-alone power system – An example of this is in cellphone base stations where no grid power is available. The battery can be used alongside solar or wind power sources to compensate for their fluctuating power levels and alongside a generator to make the most efficient use of it to save fuel. Currently, flow batteries are being used in solar micro grid applications throughout the Caribbean.

Note : Advantages of flow batteries means they might start to seriously compete with lithium-ion batteries to become the de facto battery storage technology in the future - but first, flow battery manufacturers need to get costs down to a level that's more reasonable for mass-market adoption, and iron out some challenges in manufacturing them consistently.

^{Hope This post be helpful to you (JajakAllahu Khair)}

Lithium-ion battery

In off-grid solar technology batteries are the main source of reserved energy after it is been charged by the solar panels.In solar technology there are different types of batteries  available like Lead-acid batteries , or Lithium-ion batteries or Sodium Nickel Chloride or Flow batteries.In this section we are going to learn lithium-ion batteries.


A lithium-ion battery or Li-ion battery (abbreviated as LIB) is a type of rechargeable battery in which lithium ions move from the negative electrode to the positive electrode during discharge and back when charging. Li-ion batteries use an intercalated lithium compound as one electrode material, compared to the metallic lithium used in a non-rechargeable lithium battery. The electrolyte, which allows for ionic movement, and the two electrodes are the constituent components of a lithium-ion battery cell.


For many years, nickel-cadmium had been the only suitable battery for portable equipment from wireless communications to mobile computing. Nickel-metal-hydride and lithium-ion emerged In the early 1990s, fighting nose-to-nose to gain customer's acceptance. Today, lithium-ion is the fastest growing and most promising battery chemistry.




Lithium-ion (or Li-ion) batteries are the type of batteries you get in your Phone and laptop. They are also the type of battery that is inside the Tesla Powerwall.


In fact, Tesla simply connect thousands of AA sized Lithium-ion cells together and assemble them into a liquid-cooled battery pack, wrapped in a strong metal enclosure, which in turn is wrapped in their hallmark fancy plastic shield.There are many more companies coming to market with Li-ion battery packs as we speak. This technology has a very good chance of becoming the most popular home battery technology over the next few years.

Electro-Chemistry :


The reactants in the electrochemical reactions in a lithium-ion battery are the negative and positive electrodes and the electrolyte providing a conductive medium for lithium ions to move between the electrodes. Electrical energy flows out from or in to the battery when electrons flow through an external circuit during discharge or charge, respectively.







Both electrodes allow lithium ions to move in and out of their structures with a process called insertion or extraction , respectively. During discharge, the (positive) lithium ions move from the negative electrode usually graphite to the positive electrode (forming a lithium compound) through the electrolyte while the electrons flow through the external circuit in the same direction. When the cell is charging,the reverse occurs with the lithium ions and electrons moved back into the negative electrode in a net higher energy state. The following equations exemplify the chemistry.




The full reaction (left: charged, right: discharged) being

During discharge, lithium ions (Li+) carry the current within the battery from the negative to the positive electrode, through the non-aqueous electrolyte and separator diaphragm.During charging, an external electrical power source (the charging circuit) applies an over-voltage (a higher voltage than the battery produces, of the same polarity), forcing a charging current to flow within the battery from the positive to the negative electrode, i.e. in the reverse direction of a discharge current under normal conditions. The lithium ions then migrate from the positive to the negative electrode, where they become embedded in the porous electrode material in a process known as intercalation.




The increasing demand for batteries has led vendors and academics to focus on improving the energy density, operating temperature,safety, durability, charging time, output power, and cost of lithium ion battery technology. The following materials have been used in commercially available cells. Research into other materials continues.

Distinguishing between different types of lithium-ion batteries:

There are two core lithium-ion battery technologies: NMC (Nickle Manganese Cobalt) and LiFePO (Lithium Iron Phosphate)NMC battery technology, with its high energy density, is well suited to electric vehicles, whereas LiFePO technology is better suited to residential storage applications.The Tesla Powerwall 2, as well as the LG Chem RESU, uses NMC technology, and those companies will argue vigorously that NMC is the best bet for your home.Brands such as Simpliphi and DCS use LiFePO technology, and like to point out that LiFePO is inherently safer because it is harder to make them go into thermal runaway, otherwise known as exploding.You may ask why companies would use NMC technology for residential storage.The short answer is - because their factories (like Tesla's Gigafactory) are already cranking out massive amounts of NMC lithium-ion batteries for electric vehicles, so they figure they may as well use them in a residential battery as well.NMC batteries are also, for now, cheaper to produce than LiFePO batteries. This may factor into why some companies favor NMC technology over LiFePO.

Advantages :

• High energy density - potential for yet higher capacities.

• Does not need prolonged priming when new. One regular charge is all that's needed.

• Relatively low self-discharge - self-discharge is less than half that of nickel-based batteries.

• Low Maintenance - no periodic discharge is needed; there is no memory.

• Specialty cells can provide very high current to applications such as power tools.

Disadvantages : 

• Requires protection circuit to maintain voltage and current within safe limits.

• Subject to aging, even if not in use - storage in a cool place at 40% charge reduces the aging effect.

• Transportation restrictions - shipment of larger quantities may be subject to regulatory control. This restriction does not apply to personal carry-on batteries.

• Expensive to manufacture - about 40 percent higher in cost than nickel-cadmium.

• Not fully mature - metals and chemicals are changing on a continuing basis.

This is mainly due to the fact that lithium-ion batteries can be discharged deeper and have a longer lifetime than lead-acid batteries. They will give you around 4,000 - 6,000 cycles at 80% discharge - so they will have a lifespan of 13-18 years.Their main drawback, at least at the moment, is that they are about 50% more expensive than lead-acid batteries for the same amount of storage. This is expected to change rapidly over the next 5 years, however, as mass-production of lithium-ion batteries (like at Tesla's battery factory, the Gigafactory) significantly reduces the cost of lithium-ion storage.

Hope you enjoyed this post (JajaKallahu Khair)

Why DC Products

The global domination on solar energy is prevailing and manufacturer and consumers are waiting for something that can be more useful than  solar energy it self. DC electrical equipment are getting more popular with solar energy system.Most of the DC products are available worldwide now and they are pretty cheap too in comparison with AC products more or less.DC products are really really cool products when it combine with solar energy.DC products consume lower  power than any AC products about 1/3 of AC products.Even DC air conditioner of 24V consume below 900W where AC air conditioner   consume more than 2000W. 

Let me  give you some demonstration : 

Let check some AC & DC products  : 

DC Bulb : In the house the electrical appliance which mostly used by the consumers is the electrical bulbs.  DC bulbs are way less power consuming then AC bulbs with great light intensity.

DC bulbs are showing 5~10 times more efficiency than AC bulbs and that is amazing . (Alhamdulillah)

DC bulbs have better lifespan and quality.

DC bulbs are electric bill friendly.

DC bulbs have good light intensity.

Bill comparison : Please use this bill calculator Bill Calculator

AC bulbs :  44 BDT/month for  40W 450Lm Incandescent light for daily 8 hours.

DC bulbs :  07 BDT/month for  6W 450Lm LED light for daily 8 hours.

Savings :    37 BDT /per light. (Alhamdulillah)

DC Fan : In the summer the electrical appliance we love to use the most is the electrical fan. But electrical fans are basically two types i) Ceiling Fans  ii) Table Fans.Ceiling fans are more power consuming than the table fans as the weight it rotates irrespective of AC or DC but DC electric fans are way less power consuming  and bill friendly than  AC Fans. Let me give you demonstration.
 

 

In the left picture you can see two ceiling fan data list, the first one is DC and the second one is AC.Both ceiling fan have equal rpm and weight is almost the same but the power consumption is half for the DC with compare to the AC product .The difference of these power consumption is coming from lower voltage in DC products which are like 12V/24V where AC products are 220V. 

Bill Comparison :  Please use this bill calculator Bill Calculator

DC Fan : 40 BDT/month for 38W, 8hours/day 

AC Fan : 81 BDT/month for 75W, 8 hours/day.

DC Rice Cookers : In the kitchen this is very important appliance as this can cook anything, but this is also very power consuming device which can exceed 1000W.In this case DC cooker is just a super device where dc cooker can cook with the same capacity but with lower power consumption.Let me give you a demonstration.

As you can see in the above picture AC Rice cooker with 3.2L of capacity consumes 1000W of electricity where a DC Rice cooker with 4L of capacity consumes 420W of electricity which is amazing. (Alhamdulillah)

Bill Comparison :  Please use this bill calculator Bill Calculator

AC Cooker : 135 BDT/month for 1000W, 1hours/day 

DC Cooker : 56 BDT/month for 420W, 1 hours/day. 

All of the DC products are better in performance as the power rating is lower then the AC and it brings lower electric bill but the problem is these products are designed mostly for batteries  and few cases it comes with AC/DC adapters. The following chart will give you brief idea on both DC/AC product's power consumption with the same efficiency level but you will see AC appliances  eat more power then the DC appliances   and that is why in future AC appliances will be less effective in home applications. In the chart all DC appliances are rated with 12/24/48V and AC are 110~240V.

As the Solar Energy System is a DC power source and with the help of battery storage and DC products one can get rid of  his 80% of monthly bill  easily .As the DC products are less power consuming and solar energy is coming from the sun both way it is almost like free energy and we can be grid-free home utility systems worldwide.So don't wait to install  a solar home system in your house and buy compatible DC products for your system.

Hope This Post help You (jajakallahu Khair )

Hybrid Solar Energy System (Brief)

Diesel ,Solar, Wind Hybrid System

The Concept of Hybrid Solar System is not specific all the time, it varies from system to system . But in most cases hybrid system contains a part which is off-grid or battery storage system and a part or combined parts of other energy sources or it could be grid-tied. 

Let me actually categorized for you .. In a Hybrid Solar System there are basically two parts i) Off-grid /On-grid Solar/Grid-tied  ii) Other Sources of Energy (Wind, hydro,Bio/Generators) 

These systems varies all the time but many hybrid systems are made of off-grid solar systems which are combined with other renewable or diesel generated energy sources.

Hybrid solar systems combines the best from grid-tied and off-grid solar systems. These systems can either be described as off-grid solar with utility backup power, or grid-tied solar with extra battery storage.

Grid_Tied Solar

Hybrid System also can be two renewable systems combination  where controllers controls battery charging from different  sources and later from inverters we get the AC output.

Wind,Solar Hybrid System

Hybrid Solar System Types : 

• Off -Grid Solar + On-Grid Solar (Grid-Tied)
• Off-grid Solar + Diesel Generator
• On-Grid Solar (Grid-Tied)+ Diesel Generator
• Off-grid Solar +Other Renewable (Wind, Hydro,Bio) 
• Off-grid Solar + Diesel Generator+ On-grid
• Off-grid Solar +Other Renewable (Wind, Hydro,Bio)  +Grid-Tied
• Off-grid Solar +Other Renewable (Wind, Hydro,Bio) +Diesel Generator +Grid-Tied
• Off-grid Solar +Other Renewable (Wind, Hydro,Bio) +Diesel Generator +Grid-Tied+Solar Thermal

 Advantages of Hybrid Systems :

• Save off-peak energy cost 
• Make Grid-free energy system 
• Create business opportunities with the government or local
• Save from load-shedding/black-our problems
• Highly advanced energy system 
• Help to improve individual home/business status
• Can eradicate financial issues by installing smart. 
• Better use of environmental resources  with conventional sources.

 Disadvantages of Hybrid Systems :

•  High initial Cost for set up a Hybrid System.
•  Very complex system for maintenance.
•  High observation is needed & monitoring is important.
•  Need more place to install. 

 Hope You Like this Post (jajakallahu khair)