Are You Really "Off the Grid" with Solar?

The other day I was told a story by a colleague at work about a friend of hers that proudly proclaimed that they were "off the grid" because of their new solar PV system. Fortunately my colleague knew better, and proceeded to explain to the proud new solar owners that they were not off the grid, and that in fact they relied on the utility electrical grid to make their solar system work. How so, the now a bit deflated solar owners asked? The solar PV system that these home owners installed on the roof of their home must operate in parallel with the utility electrical grid, meaning that the solar PV system must operate within established parameters of how the utility electrical grid operates. If this weren't the case, there would be problems.

For example, if the utility electrical grid goes down, the solar PV system must turn itself off and not deliver energy to the homeowners electrical panel. Why? Safety. Electricity flows along the path of least resistance, and if that happens to be the lineman that is working to fix a fault on the electric grid, that lineman is in danger of being subject to an electrical shock. If the solar PV system did not shut down, it could feed the generated electricity back onto the distribution electrical system (aka grid) and create a shock hazard to anyone who happened to be working on the grid. This is a situation that all would agree is to be avoided. We depend on our fabulous lineman to maintain and keep the grid in optimal working condition, and to fix the grid when it breaks, like during a big storm, or when someone knocks down a power pole.

A less serious reason for why a solar PV system relies upon the grid to operate properly is that sometimes you don't need all the energy that the solar PV system generates. Maybe you're not home during the day, or your usage of electricity at any given period of time is not sufficient to use all of the solar PV generated electricity. During these times the solar system will push electricity back out onto the grid, in accordance with our Net Energy Metering tariff and rules. This is good for you and your solar PV system, because without it, you would have to either shut off your solar PV system, throttle it down to match your usage, or find some way to store the electricity that you don't need at the moment. By pushing the electricity back onto the grid, you allow the solar PV system to operate in an optimal manner, and in essence use the grid as your electricity storage system. This is the "turning the meter backward" concept, which is why it's called Net Energy Metering. What you pay for electricity depends on how much you use from the utility versus how much electricity you use from the solar PV system including how much solar generated electricity was pushed back onto the grid. The utility keeps track of how much you "import" from the utility versus how much your solar PV system "exports" back onto the grid, and the utility bill that you recieve nets out these values. If you were "off the grid" you would have to manage your solar PV system in some other manner, most likely by purchasing an energy storage device, like batteries. This will add costs and complexity to your solar PV system and require additional maintenance.

Plus, there is also that thing about what to do during the evening hours when the sun isn't shining and your solar PV system isn't generating electricity and you want to watch your favorite TV shows on your big screen TV or maybe contribute to a blog on your home computer. Have to get that electricity from somewhere, and that's either the extra expense you put into batteries, or you get it from your friendly neighborhood electric utility.

A solar PV system can be a wonderful tool in helping you manage your electricity costs and usage, as well as contributing to the reduction of your carbon footprint, but your electric utility is still a piece of the puzzle and a valuable resource to you in managing the energy your solar PV system generates.