Solar power is a great source of renewable energy that can be used to lower the carbon footprint of your building and also the monthly energy bills.
If you live in an area where the grid is available, you can install an on grid solar system (grid-tied solar PV system), which will be connected to the grid all the time despite the fact that you generate your own power using solar panels.
In case of a power outage, your house will remain without power because the PV system will be disconnected from the grid.
Solar panels won’t work to protect the workers sent to fix the problem in the grid.
If you live in an area where the grid is not an option, you can produce your own power installing an off-grid solar PV system.
An off-grid PV system will make you energy independent (you will produce your own power), you will no longer pay energy bills, and you will protect the environment by releasing a reduced amount of greenhouse gas emissions into the atmosphere.
On Grid vs Off Grid Solar Panels
Grid-tied Solar PV System
On grid or grid-tied solar PV systems allow you to remain connected to the grid while producing your own power.
To get solar power into a home that is grid connected, you have to install a solar PV system on the roof or in the yard.
This type of PV system uses a grid tie inverter that takes the DC energy produced by the panels and converts it into AC power, which can be used in your home.
An on grid PV system represents one of the cheapest and most efficient ways to power your home with solar energy.
MPPT System
Another option is to use a MPPT system (maximum power point tracking), which uses more elements in the system.
The solar panels installed on the roof convert the sunlight into DC power, which goes through a charge controller, and from there to batteries to charge them.
The batteries feed an inverter that turns DC power into AC power (alternating current), which can be used in the house to power appliances, gadgets and many other things.
However, every time power goes through a device, there will be losses.
Some power is lost when the energy produced by the panels goes through the charge controller, and there is another small loss of power when the energy is sent to feed the batteries.
Another loss of energy occurs when the power goes from the battery to the inverter and finally in the house.
There are losses at every step before the power produced by the panels reaches your house, which makes the system less efficient.
In case of a grid-tied PV system, you don’t have to use batteries.
A battery system is good only if you want to store the excess energy produced by the panels (instead of sending it back to the grid), which will significantly reduce your energy bills.
Batteries can be used as backup for cloudy days and are very useful if you live in an area where power outages occur pretty often.
Batteries are expensive, so if you are connected to the grid, but you want solar panels on your roof, it’s enough to install a grid-tied solar PV system that uses a grid tie inverter.
No batteries are involved here, so the system will be more efficient (energy loss is minimal due to the reduced number of components in the system).
Off Grid Solar PV System
If you have a farm, a vacation home in the woods or up on the mountain, it can cost a good amount of money to bring the grid to your home.
In this case, it is far more efficient to install an off grid solar system, to produce your own energy using the small solar power plant installed on the roof.
Before installing the off grid PV system, you have to carefully calculate what are your power requirements because the PV system must be properly sized according to the power demand of your home.
The energy produced by the panels must cover the power demand for heating, cooking, working and entertainment.
Any extra power you will need, has to be accounted for and produced using additional panels, maybe a bigger charge controller, and of course a battery system to store some of the energy produced during the day.
An off grid solar system can potentially run far more efficiently as most grid-connected systems because it doesn’t need to make the accommodation to electrical appliances running up to 220V (volt).
When using an off grid system, is essential to use a charge controller because you have to control the amount of energy sent to the batteries.
The MPPT charge controller makes the collection of power from your solar panels much more efficient, and can run your household at 12V, 24V or 48V.
If you have a 12V system, you can potentially power your lighting directly from it, this means that you are no longer using an inverter, which makes the use of power produced by the panels far more efficient.
However, to run other things in the house, you have to introduce an inverter because some entertainment systems and appliances need 110V or 220V to run.
Final conclusion
This is the difference between on grid and off grid solar.
Remember, on grid solar systems (using grid tie inverters) are much more economical because they don’t need to charge batteries (the system involves less elements).
The excess energy produced by the panels is sent back to the grid to power your neighbors, and this helps you to save some money on energy bills.
In case of a power outage, your house will remain without power because the panels on the roof will be disconnected from the grid to protect the workers sent to fix the problem.
If you use an off grid solar system, you don’t have access to the grid, but you will become energy independent (you will generate your own power), and you will no longer pay energy bills to utility companies.
