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Grid tied systems explained

A lot of people believe they are becoming "power independent" by installing grid-tie solar systems, but what many don't realize is that virtually all such systems are designed to actively go off-line when the power grid goes off-line

A "grid-tie" energy system is one that ties into the power grid, pulling electricity from the grid when needed, then pushing excess electricity back into the grid when the local customer isn't using the full capacity being generated by the wind or solar. As long as the grid stays up, it's a clever solution because it reduces or even eliminates the customer's electric bills while generating "clean" energy.

Because of the very fact that these systems are tied into the power grid, however, they all have a safety feature that disconnects them from the grid when the grid goes down. In other words, if the power grid goes off-line, your entire grid-tie system becomes instantly useless and you can't power a laptop computer even if you have $100,000 worth of solar panels sitting on your roof. In a grid-tie system, they all are instantly shut off.

Let me be clear, because some people reading this article seem to vastly misunderstand the issue: When the power grid goes down, your entire PV array is instantly disabled by your grid-tie inverters, and you cannot use your PV array for anything! Even if the sun is shining, you will have no power from it, period. Understand?

Some early comments to this story suggested that people could simply install a throw switch that would divert the PV array to local use only. This is NOT allowed by local electrical code! Such a system is very difficult to engineer in a safe manner and would almost certainly violate local codes in nearly all countries. It simply will NOT pass inspection and will not be allowed in most areas.

It's a "safety" feature

Four out of five people reading this will not believe this information because it is so counter-intuitive. I spoke with architects and engineers who didn't even know this information. They were all proven wrong. If you install a grid-tie system, the entire system is immediately useless when the grid goes down. That's the way grid-tie systems work. There is no BYPASS function. Grid down = solar array down, period.

What's the reason behind all this? Because if the main power grid is down, the assumption is that a power line worker may be working on the line somewhere. If a local solar customer is feeding electricity back up the line, that can be dangerous -- even deadly -- to a power line worker. Thus, all grid-tie solar equipment sold today includes the "safety feature" of automatically shutting down when the grid goes down.

Off-grid systems

"Off-grid" systems however are not affected by the grid. These systems, which do not tie into the power grid, run on a combination of solar panels, batteries and/or wind with sometimes a backup generator running on gasoline, diesel or propane.

But Off-grid systems are ridiculously expensive to own and operate, mostly due to the cost of batteries. Today's battery technology remains stuck in the 1800's, meaning that even so-called "deep cycle" batteries will still last only a few years. If you do the math on the cost of batteries for a typical off-grid system running a household of four people, you'll come to the surprising figure that batteries alone can cost you over $500 / month, each and every month that you use an off-grid system (that's the total cost of the batteries divided by the number of months they will last). The ROI (return on investment) is ridiculously long and just not worth considering unless you are in a location without any grid supply.

That's why most people don't go with off-grid systems. Grid-tie systems cost significantly less and use no expensive batteries and give the advantage of selling energy back to the grid to further reduce your homes running costs.

Only an off-grid system gives you true energy independence.

Many people who buy grid-tie systems mistakenly think they're buying off-grid systems

The kicker in all this is that many people mistakenly think they're buying one kind of system when, in reality, they're buying the other kind. Solar installation companies that install grid-tie systems do not necessarily inform their customers that their systems will not function when the power grid goes down. So these customers, even after spending $20,000 to $80,000 or even more, end up with a system that's 100% dependent on the power grid!

There's going to be a rude awakening for these people if the power grid goes down and their systems refuse to function. Because, for most people installing solar/wind systems today, the whole idea is to have power when the grid goes down. But thats simply NOT POSSIBLE!

Off-grid solar equipment is in short supply

As you probably suspected, the kind of solar equipment used to build off-grid systems -- the kind that function without the power grid -- is in very short supply. Manufacturers in Germany, Japan and China are back ordered for months. Install times for new systems can now stretch out as long as six months in some cities. Those who want to be safe, prepared and living with a source of electricity need to take steps now to install off-grid systems now - if their pockets are deep enough and they don't mind paying through the nose for energy.

Just in case you are thinking otherwise, Yes, even off-grid systems are vulnerable to solar flares and EMP attacks. There's no protecting fragile electronics from such events unless you keep a spare set of redundant equipment protected inside Faraday cages or wrapped in aluminum foil and stored inside galvanized aluminum trash cans. Even then, you'd have to figure out how to reinstall everything from the ground up, which would require an expert electrician.

In summary, if you live where there is a reasonably reliable grid supply, it would be a ridiculous financial investment to install an 'off grid' system. Off grid is only financially viable in remote areas that have no national grid. Whereas if there is a national grid, a grid tied system can save you a fortune in energy costs over the years.

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