On-grid Inverter

On-grid or grid-tie solar inverters are by far the most common and widely used by for homes and commercial purpose. These inverters do not require batteries and use solar inverters and are connected to the electricity grid. Whatever excess solar power is generated is exported to the electricity grid and owner get paid a feed-in-tariff (FiT) or credits for the energy you export.

But there is a challenge, On-grid solar inverters or Grid Tied Inverters are unable to work or generate electricity during a blackout due to safety reasons. Since blackouts usually occur when the power grid is malfunctions; If the solar inverter was still feeding electricity into a damaged grid it would risk the safety of the people repairing the fault/s in the network. It also stops working during voltage fluctuation. In both the cases there will be wastage of Solar Energy.

Off-grid Inverter

Off-grid inverters are not connected to the power grid that is why they require batteries for power storage. Off-grid solar systems must be designed such a way that they generate enough power throughout the year and have enough battery capacity to meet the home’s requirements, even in winters and monsoon when there is less sunlight.

High cost of batteries and off-grid inverters means off-grid systems are much more expensive compare to on-grid systems and so are usually only needed in places which are in remote areas and are far from power grid like vacation homes, resorts, farm houses etc.

What is Hybrid Solar System?

A hybrid solar system has best of both On grid and off grid.  It combine solar and battery storage in one and are now available in many different sizes and configurations. Due to the decreasing cost of battery storage, systems that are already connected to the power grid can start taking advantage of battery storage as well. This means storing solar energy which is generated during the day and it at night. When the stored energy is less, the grid is there as a back-up, allowing consumers to have the best of both worlds.

Hybrid Solar Inverter allow full control over your power, while keeping you grid-connected in case of emergency.  Hybrid Solar systems generate power similar to a normal grid-tie solar system but use special hybrid inverters and batteries to store power for later use. This quality to store energy enables most hybrid systems to also operate as a backup power supply during a power outage like UPS.

If there is a power failure or the grid becomes unstable the unit will automatically switch over to battery supply immediately and continue to operate independently from the electricity grid.

Why to store solar energy in a battery?

Many governments and network operators have reduced the solar feed-in tariff or FiT. This means traditional grid tied systems have become less attractive as most people are working during the day and not at home to use the solar energy as it is generated, thus the energy is fed into the grid for very little return.

solar hybrid system stores your excess solar energy and can also provide back-up power during a power outage. This is perfect for domestic use, farm houses, resorts, vacation homes etc.

Hybrid Solar Systems enable you to store solar energy and use it when you face an electricity cut.

The ability to store and use your solar energy when desired is referred to as self-use or self-consumption. It works in the same way as an off-grid power system but the battery capacity required is far less, usually just enough to cover peak consumption (8 hours or less) as opposed to 3-5 days with a typical off-grid system.

Key benefits of hybrid systems

Hybrid inverters have many advantages – here are some of the top ones to consider:


A common misbelief about solar is that if you install a Grid Tied inverter, you’ll always have power during outages. In most cases, this is not true. Traditional GTI systems automatically shut off during power failure for safety purposes, cutting off power generation from your solar panel system.

If you want to keep your home or commercial establishment running on backup solar power during a grid failure, hybrid solar system paired with batteries are perfect solution. Some hybrid inverters have both on-grid and off-grid capabilities, allowing you to continue running on solar power even if the grid fail.

Easy Monitoring

With a hybrid solar inverter, all of your solar electricity–whether being sent to the grid, self-consumed on your property, or being stored in your battery–is converted through one component. This allows for “centralized monitoring,” which means you can monitor both your solar panel system and battery performance through one platform.

Easier installation process

One of the biggest benefits of a hybrid solar inverter is that it combines the functionality of two separate pieces of equipment into one. This mean an easier installation process for your solar installer. Depending on the prices of the individual components and the labour cost, you may save money by installing a hybrid inverter from the get-go as opposed to paying for both a solar inverter and a battery-specific inverter separately.

Future-ready (Add- on is possible)

A hybrid system is possibly the most expandable, future-ready home solar setup. With some customisable hybrid systems, you can expand capacity by buying more panels or batteries. Hybrid systems may also be compatible with newer solar technologies — for example, an electric vehicle (EV) might function as one of the ‘batteries’ in a hybrid setup.

Latest Technology

While Off Grid is an obsolete technology, Hybrid Solar System is latest, cost effective and more useful.

Have you experienced a power outage when you were in a moving lift/elevator that stopped with a sudden jerk at society or hospital or business house or listened about it?  What panic you observed there. I was trapped once in the cabin of our society’s lift with my little daughter. She was very terrified when the lift stopped suddenly with darkness between the two floors. And the situation can become worse in the closed lift if there are pregnant women, children, senior citizens, and patients with high blood pressure, heart disease, etc.

But there is a fullproof solution to this horrifying situation and claustrophobia of people if lifts/elevators are attached with Emergency Rescue Device (ERD). An Emergency Rescue Device (ERD) is an electronic and electrical apparatus that provides emergency power back up to the lift or elevators with almost zero switching time when the input power source or mains power supply fails suddenly. The power supply outage can be due to a fault, shortage of power, Natural Disaster, or Fire.

ERD, ARD & Generator As Lift Power Backup

An Emergency Rescue Device (ERD) differs from an auxiliary or any other power backup system like Generator and Automatic Rescue Device (ARD). No Generator or existing ARD system available in the market can provide smooth operation of elevators like an ERD during a critical period of a power failure, fire, or earthquake.

Generator as Power Backup for Lift 

There are two types of generator sets, Automatic Genset & Manual Genset, attached with the Control Panel that supply current to the motor for the movement of Lift/Elevator upward and downward. If the power supply fails due to any reason like power shortage, Fire, or Natural disaster, the Automatic Genset takes 45 Sec to 1 minute to provide power to the lift. Whereas in the same situation, Manual Genset takes 2 to 5 minutes to restore the power supply. Here we can think of a horrible and terrifying situation if there are Children, Pregnant women, Sr. Citizens, or critical patients on the 11th Floor and the lift stops suddenly with a waiting time of 45 Sec to 5 Minutes to resume power by Generator.

Automatic Rescue Device (ARD) as Power Backup for Lift

An Automatic Rescue Device (ARD)is a device used to stop the lift first when the main power supply is cut suddenly and rechecks all the circuits to confirm if everything is okay. This process takes at least 45 Sec and then it moves the lift to the next lower or upper floor with a lot of jerks and turbulence. It causes different problems to heart patients and pregnant women can have long terms issues in that state. It also damages the electronic mechanism of the device and becomes one of the major causes of the lift’s costly maintenance.

What is Emergency Rescue Device (ERD) & how it differs from ARD and DG? 

An Emergency Rescue Device (ERD) is an electronic and electrical apparatus based on future technology developed by collective efforts of qualified and experienced electronic, electrical, and computer hardware & software engineers. An ERD provides emergency power to the lifts/elevators with a 3-phase power supply, when the mains power fails. It differs from any other emergency power system, like a generator or ARD, because it provides near-instantaneous protection from input power cut by supplying electric current stored in batteries with zero switching time.

The technology used in the development of ERD is different from inverter technology. The ERD technology is specially designed for lift loads only.  It takes care of the regenerative load and the switching time is almost zero. As a result, the lift/ elevator does not come to know of the switching from one load to another.

What are the features of the Emergency Rescue Device (ERD)?

In a nutshell, the ERD has different features like a lift emergency power backup, for examples:

  • It provides smooth running if the power supply goes off suddenly.
  • It gets off at any floor without any sudden jerk.
  • There is no fear and claustrophobia in the mind of lift users inside the cabin.
  • There is a panel inside the lift to show the status of power and its back up.
  • There is no chance of damage of elevators for the sudden stop or excess current at the start. And finally
  • It provides complete peace of mind to lift’s users whether they use it in high-rise apartments or hospitals, or business offices.

What are the key benefits of ERD? 

There are various benefits of ERD if it is attached to a control panel which supplies current to the electric motor to move the lift up or down:

1. ERD Protects Lift Users Life

When people are stuck in closed lifts/elevators due to sudden power outage, it creates a fear psychosis through claustrophobia and they feel choked despite proper ventilation in the lift. According to the American Journal of Psychology, this can aggravate serious and life-threatening situations for the lifts’ occupants, especially kids, pregnant women, elders, disabled, and serious patients.  This small time-lapse of 30 to 45 seconds can lead to panic and horrible situations like fainting of occupants to such a situation that can trigger cardiac arrest.

2. ERD Prevents Apparatus Damages

The switching time of most Diesel Generators to supply backup current to lift control panel is relatively sluggish from 90 seconds to 5 minutes or more that causes lift electronic parts damages. But in the case of ERD, the switching time is almost zero that prevents damage to the lift’s electronic mechanisms in the long run.

3. ERD Saves Lift’s Users from Disaster

An ERD provides an uninterruptible electronically controlled software program-based power supply to the lifts in all scenarios. It includes natural disasters like Fire, Earthquake, and Grid Failure, especially for high risers in urban areas. For example, in case of fire main power supply is cut and survivors on the upper floors can come down with the help of the ERD power supply and saving them from any untoward happenings.

4. ERD will be the only power backup in future  (Add-on Point)

ERD will become the only option for power backup because generators emit particulate matter containing burnt hydrocarbons and nitrogen oxides (NO2). These hydrocarbons and NOadd to air pollution. If the generator is in bad condition, it can also emit unburnt hydrocarbons, which are even worse for the environment. They also produce noise. So generators are getting banned in most of the cities in future as pollution is a big challenge for the future generations. Moreover, ERD can give as much power back up as required by the generator without any rest.

Thus ERD-enabled lifts eliminate the most horrible situation while providing disaster resilience to the buildings, users, and operators. And it saves the lives of lift users in an economical and environment-friendly manner that no generator or existing ARD system can provide.

Advantages of ERD in Brief 

  • ERD is environment friendly as it does not produce air pollution, noise pollution, or vibration and it can be solar-powered.
  • ERD is developed and based on Disaster Response Management System. It maintains Fire Safety norms for the lifts and protects against Lift accidents due to power failure and earthquake.
  • ERD is cost-effective in the market if compared with the size and load of UPS’s cost. It has less running cost of electricity and longer life of its Batteries.
  • It can provide the backup time to run the lifts from 10 cycles of lift operations to 2,000 cycles depending on the load capacity of ERD attached to the control panel. And the one cycle counts for the complete one operation of the lifts from ground to top floor and top floor to ground floor.
  • Lithium batteries can also be used in ERD for saving space and maintaining the longevity of battery life and reduction of the battery’s weight.
  • The ERD is technologically designed to put on solar charge controller externally for saving the electricity cost and providing complete green solution prescribed by the green building norms.
  • Thus, ERD is the “All in One” Power Backup Solution for Lifts and Elevators that works with minimal human intervention and saves lives, apparatus, lifts, cost, and environment.

The latest lithium battery technology is going to change the paradigm of storage solutions in the long run, as today people are using different types of lead acid batteries for storage, which are SMF, tubular, or gel-based tubular or SMF technologies, which have a litany of challenges and limitations.

The first limitation is cycle life as a lead acid battery cannot match the cycle life of a lithium battery. In literal terms, the lead acid battery life is defined by various parameters, one of which is the refilling of battery water, which is a big challenge for the user as they are not able to fill the water in time, and what kind of water they are supposed to fill is another challenge as they fill with any RO water or normal water, which destroys even the normal cycle life. The gel battery has the challenge of a higher temperature, so the performance goes down if the temperature is higher than a certain defined value.

Whereas lithium batteries, particularly LifePO4, are a very stable technology that has been proven for nearly two decades now, and the cycle life varies on the good BMS that regulates proper charging and discharging so that the battery has minimal heating inside, we can get anywhere between 1500 and 4000 cycles, whereas the lead acid battery cannot perform more than 400 to 500 cycles or so clear in terms of cycle life.

Another important factor is capacity at different discharge levels. As a result, lead acid batteries are typically designed at C20, which means that you can only discharge 5% of the battery before reaching the rated capacity. which is also not available as the process of making lead acid is very crude, and obtaining consistent power is a challenge. If you discharge the battery at 50% capacity, you will get 50% of its rated capacity. Whereas lithium is a C1 battery, so at any load, the capacity remains 100%. which is a very big difference when we use these batteries for storage purposes like inverters, UPS, and solar solutions. The lead-acid backup time can’t match the lithium battery pack.

Another major challenge is the cell balancing option available in the lithium battery pack in the BMS, which is one of the reasons that battery life can be achieved as a lead acid battery has six cells that cannot be balanced as there is no provision inside the battery. If we need to operate at higher DC voltages, we must balance the batteries, which the user does not do.

So if we need to put 120 V DC, then we need 10 lead acid batteries, which take up a lot of space, and they can’t be balanced with each other. The internal cells of each battery pack are also not possible, and the connecting wires take a longer route, which becomes another challenge as each battery takes up its own space, and we need to keep them at a distance, which creates wire losses. In contrast, lithium is a single pack that is one-fourth the size of a lead acid battery bank. So there are hardly any losses between the battery cells, which keeps minimum losses and cell balancing for each cell balanced through the BMS. So at the end, there is no comparison between lead acid batteries and lithium batteries. In the next 5 years, there will be a revolution in the industry, and lead acid will be out of business in the storage business.