Using solar power in home applications has become increasingly common as the price of the system components has come down in recent years. In many cases, governments looking to subsidize renewable energy initiatives will even help pay for some or all of the cost of installation for those who decide to put solar panels on their roofs and property in order to generate power that goes back to the grid.
No matter what the overall configuration, any solar power system that intends to use this power for home application includes a solar inverter. The power that is generated by solar panels is DC but homes require AC, as does the power grid. Therefore, inverters are a requirement. If you are struggling with the question of whether or not an on-grid solar inverter is right for you then you have already decided you want a solar power system. In truth, you are likely really trying to decide between three different situations. There are the all-or-nothing solar systems that are either fully on or fully off the grid. However, there is a third system that is a hybrid of the two. In this hybrid system, there is still battery storage for backup, but the system connects through an interactive inverter to the grid as well for extra redundancy. Therefore, the answer to this question is really a question of independence and reliability. If you would like to see how each system is configured and how the inverters fit in, check out this YouTube video.
On-Grid Solar Systems
An on-grid solar power system with a decent battery bank is the most simple of the three configurations. The solar panel converts the sun’s light to DC electricity which then flows to the solar inverter. AC electricity comes out of the solar inverter and goes either to the home for use or to the electric grid for storage or use elsewhere. In some cases, the governmental regulations only allow a homeowner to use power from the electric grid and they get credit back on their bill for the power that they “sell back” from their solar system. If a home is allowed to use their own solar power freely, then the home uses all of the power that is generated by the solar panels and then switches to grid power when their own solar is unavailable, such as at night or in bad weather.
The main benefit of an on-grid system is having the almost unlimited redundancy of the electric grid. Unfortunately, there is a major downside in that there is no local storage of power so if there is a local outage then the home still loses power until it is fixed.
The opposite of the on-grid system is obviously the off-grid system. Here, the connection to the power grid is completely removed so there needs to be another source of backup power. Frequently it is either a battery or a generator. Generators tend to be much less common since they should really only be used for emergencies due to the massive amount of fuel consumption it would require to power a house on a nightly basis. So, off-grid solar systems with a battery bank are ideal. These batteries store DC power so the solar inverter in an off-grid system must take in and convert power from both the solar panels and the batteries. Due to this configuration, these inverters tend to be a bit more sophisticated and can balance the power needs of the household between the two power sources. While the idea of being totally independent of the electric utility may seem attractive, batteries tend to be very expensive so the cost can be prohibitive to going fully off grid.
Hybrid Solar Systems
For those who want some sort of balance between cost and reliability, the hybrid system tends to be the answer. In this configuration, there are actually two inverters. A traditional solar inverter is used between the solar panel and home as the primary source of power. However, a more complicated interactive inverter is often used between the grid, a batter storage source, and the home to manage where the power comes from when the solar panel is not generating any. If the solar panel is generating more electricity than the home needs, it will charge the battery until full. When the battery fills up power will start going back to the grid. Conversely, if the panel stops providing power the home will start drawing power from the battery. When the battery is empty the house will then receive power from the grid.
The primary benefit of this setup is the extra redundancy. Users of a hybrid system have the benefit of knowing there is the unlimited backup of the power grid if their system manages to run out of its stores, but they are also not subject to power outages in the same way that those with a purely on grid system would be. As long as there is the sun in the sky and the battery is full, the hybrid system will keep the lights on regardless of what is going on with the electric company.
How Do You Decide?
When you are thinking about whether or not an on-grid solar inverter is right for you, considering the following questions may help point you in the right direction.
- What source of redundancy would be best for me?
- How much do I value independence?
- How much money do I have to invest in a solar system?
- How would a power outage affect me?
- How much space do I have to devote to this system?
- How much sun does my area get on a regular basis?
- How frequently do we have bad weather?
- How frequently do I have long power outages and just how long are they?
These questions can get you started in the right direction, but Off the Grid News also has a nice article that explains the pros and cons of being on and off the grid as well.