Hello everyone! This week’s blog topic is all about the advantages and disadvantages of taking your home off grid - we’re comparing off-grid to a more traditional grid-tied setup. We’ve received much interest on this topic and hopefully putting all the information together helps shed some light on this somewhat misunderstood topic.
First, it is important to understand how a traditional grid-tied solar array works. We’ll look closely at arrangements that either produce 100% of your annual production or are capable of taking your home 100% off-grid.
In this setup, you keep access to the electrical grid and use solar as a supplement. During the day, solar electricity powers everything in your home and some excess is sold back through the grid to an electrical provider. The excess is generally treated as a credit that helps the homeowner offset nighttime usage. With a large enough solar panel system it’s possible to get your monthly bill to $0 or even have a credit some months.
What this takes:
Solar array sized to match the home’s electrical consumption
A local electrical retail provider that offers a solar buyback plan (which is how you get money for your net export).
TDSP (Transmission/Distribution Service Provider) that is willing to facilitate two-way or net metering options (this will always be the case if the above is found available).
The system connects directly through your electrical panel. Any electrical draws will pull first from the solar power provided and second any remaining demand is pulled through the main power feed. When more power is being produced than consumed, it flows back through the grid.
This type of system is the “leanest” option with the lowest upfront and maintenance costs.
This type of system is more complicated to design than a standard grid-tied system. The system does not have access to grid electrical power and instead will need batteries to store the energy you produce. Due to this, you now need to also consider monthly, even weekly production requirements. If your system doesn’t produce as much as needed in the summer or winter you would experience outages. This is far from ideal and to avoid that you need two things:
A larger solar array sized to exceed your consumption each month of the year. There is usually a 15-25% oversize to help account for prolonged periods of poor weather.
A battery bank capable of storing power for your home for 2-3 days (1 day is not recommended)
Additionally, if you are concerned about week-long stretches of poor weather (during daytime), you could add a generator. This has the additional advantage of letting you use a smaller solar array with less worry.
It’s important to know that the cost of a battery bank is often equivalent or close to what a turnkey installation would cost without batteries. Additionally, batteries have a shorter life expectancy than a solar array. You may need to replace your battery bank anywhere from 3-10 year, depending on which batteries you select.
This means that from a cost perspective, off-grid systems end up much more expensive when compared with a grid-tied system for the same home. As such, they are mostly good ideas when power is extremely difficult to get or expensive.
Let’s look at the two types in a more exacting comparison.