Off Grid Solar System:
It is for use in house purpose. It is not being connected to any commercial power and having total independence. In order to do this, you need to calculate the total consumption of what your house or cottage consumes in watt hrs. This is also how the power company monitors your power consumption too. Now, according to the total amount of watt hrs you consume in that period of time is going to be relative to the sizing of your battery system you are going to need to store that power. Once you have stored power an inverter will be needed to convert from DC power to AC power.
- Solar Hybrid Solar PV Systems: If you were thinking that there is nothing stopping you from having both types of system installed at the same time you would be absolutely right. A Hybrid system gives you all the benefits of both systems with the added benefits from protection from power cuts and outages (from either solar or mains), coupled with the ability to live independently of fossil fuels whilst supplying others with clean, green energy. A Hybrid Solar PV System would utilize a connection to the grid enabling power to be exported and also use batteries to protect against power cuts and store power for use locally.
- Stand Alone Solar PV Systems: Poor quality of grid supply (low voltage, fluctuating frequency and frequent interruptions), high tariffs (much higher than actual cost of supply), unfair impositions (peak hour restrictions and unplanned load shedding) and unresponsive attitude of State Electricity Boards have forced many industries to isolate themselves totally from the state grid and be on their own. For a reliable operation of the industry, they necessarily have to employ captive generation with a redundancy. Stand-alone PV systems are designed to operate independent of the electric utility grid, and are generally designed and sized to supply certain DC and/or AC electrical loads.
On Grid Solar System:
It is for use in house purpose and to supply back to grid. It is a system where you will still use commercial power for your appliances. You can also incorporate a battery system, if you wanted to operate an off grid system also. But mainly what this does is if any power that is generated is greater than that power consumed commercially, can be sold back to your power company. This can be done with a special type of inverter which is directly connected to you meter box.
- Grid Connected Solar PV Systems without backup: A grid-tied system is made up of solar panels, a grid tie inverter, and other electrical components. This is the least expensive and most logical choice if you live in an area which is serviced by the utilities. Since the power is not stored in batteries, as in an off grid solar system, there are no batteries to replace. However, this type of system provides no back-up power in case of power failure.
- Grid Connected Solar PV Systems with backup: Grid-tied with battery backup is a type of solar system which is roughly the same as the grid tied system with a couple of additions. Along with the inverter and solar panels you would need 12 volt deep cycle batteries and a solar charge controller. With the addition of the batteries comes more expense and maintenance. A solar charge controller is used to maintain the proper charge to the batteries so that overcharging will not occur. Although this system is more expensive than a grid-tied solar system, it will provide you with at least some power in the event of a power failure.