Plug and play grid tie inverters

Want more information on grid-tied ac-coupled inverter? Feel free to contact us.

Plug and play grid tie inverters

I got so excited when I read that you can buy a plug-and-play grid tie inverter and pump the electricity from your solar panel directly into the grid for less than a hundred bucks that I snatched up the first one I saw on ebay.  The theory is sound and would make small-scale solar fit into the average person's price range...if it wasn't illegal and potentially hazardous.

The dream is that you can simply plug a solar panel directly into one of these small inverters, and plug the other end of the inverter into an electric socket in your house.  On the level I'm interested in, there's no way you'd actually be feeding energy back into the grid since continuous loads in your house (like the computer, fridge, etc.) will suck up all the juice you've created.  But you would lower your electric bill, and would also remove the most disposable part of a solar power system --- the batteries.  Without the repeated purchase of batteries, I figured even the solar panels you can buy at Harbor Freight for less than $200 would pay for themselves before they began to seriously lose efficiency.

The problem with the dream is that utilities require you to jump through such a series of hoops before tying into the grid that you might as well not even think about it unless you're willing to sink a few thousand dollars into the project.  I contacted our local electric company (Appalachian Electric Power) and found out that in order to plug in a grid tie inverter, we'd need to:

1.) sign an interconnection agreement, 2.) install a certified (UL 1741) inverter(s), and 3.) install a disconnect switch (alternating current, accessible, lockable, with visible open position) near the meter.

The employee I emailed with (who went to great lengths to make his emails understandable by the layman) explained that the existing disconnect below the meter is not sufficient to fulfill step 3.  In addition, more extensive reading on the internet shows that a certified inverter costs around $2,000, putting grid tie-in completely out of our league.

The electric company has a few valid reason to squash cheap plug-and-play inverters.  The biggest hazard from these inverters comes during power outages, when the electric company shuts down the juice on a line so that it can be repaired.  Without the proper precautions, your solar panels would continue feeding electricity into what is supposed to be a dead line, and you could fry the linemen who come to fix the problem.  Granted, even the cheap power jack grid tie inverter we found on ebay has anti-islanding protection, so presumably this problem wouldn't occur.

I read an excellent point on a forum that our grid tie inverter is inherently unsafe since it has live electricity on the male end of the plug rather than protected within a female plug.  This is where my (very mild) libertarian leanings come out --- we live in a household of two adults who can remember to unplug the solar panel before yanking the inverter out of the wall.  We're not going to fry ourselves.

Many people buy these plug-and-play grid tie inverters and surreptitiously put them to use in their own homes.  Chances are, no one at the electric company would ever find out (although if you go the illegal route and have a fire in your home, your fire insurance will probably refuse to pay for the damages.)  Unfortunately, breaking the law would keep me up at night, so we've wasted $90 on a useless grid tie inverter and will have to figure out a better way to harness the extra energy that doesn't go into charging our power packs.

The company is the world’s best 3 string inverter supplier. We are your one-stop shop for all needs. Our staff are highly-specialized and will help you find the product you need.

Looking for a cheap homestead gadget?  Try our

that will never spill or fill with poop.

Want more in-depth information? Browse through our books. Or explore more posts by date or by subject.

About us: Anna Hess and Mark Hamilton spent over a decade living self-sufficiently in the mountains of Virginia before moving north to start over from scratch in the foothills of Ohio. They've experimented with permaculture, no-till gardening, trailersteading, home-based microbusinesses and much more, writing about their adventures in both blogs and books.

Want to be notified when new comments are posted on this page? Click on the RSS button after you add a comment to subscribe to the comment feed, or simply check the box beside "email replies to me" while writing your comment.

I think the other replies have covered the fact that unpermitted grid tie is just too risky to impossible. Smart meters will detect it immediately, and analog meters might run backwards undetected until they send someone out to read it.

So that leaves the solution of having a second independent grid at home. You'd still need the inverter to output alternating current, and then you'd need breaker boxes, wiring, and outlets, so lots of extra costs. But theoretically, this works. For example you could wire up your storage shed, and then plug in a freezer and fridge set really cold. When the sun shines, they run and hopefully keep cold until the next day with sun. The one thing that solar does well is handle reduced load: if you don't have something drawing an excess of solar power, it doesn't hurt the panels or the inverter.

Someone mentioned the problem of power cycling and its effect on appliances, and I think that might be an issue as well. Appliances just aren't designed for intermittent power. I think with the spread of solar, that will change, we will get "smart" appliances that turn on when power is available, even optimize their running to use such power, and tolerate when it isn't.

But without batteries, such a system isn't really good for much. It's not like you see the sun shining, so you go use the second microwave that's plugged into the solar electricity when you want to make lunch, or worse need to unplug and move the appliance. I guess you could wire the solar system next to certain appliances, then you just have to plug and replug them in. For example, you know the sun is shining, so you go to the laundry room, replug the washer into the solar power and do laundry.

But really, solar panels only make financial sense when you can use all the power they produce. So without batteries, you'd need a load that soaks up all the solar power but doesn't mind the intermittent production. That's why I suggested a freezer, to "store" the energy as cold. An electric car might work too, but then you're limited to charging at home when it's sunny. An electric car is just a battery, but it does let you convert that stored energy to mobility.

As mentioned, the other use for solar electricity is air conditioning. Again, it doesn't work to either have 2 air conditioners or to flip a big switch every time you want to use solar, it's just not practical. However, they do make a mini-split unit that takes direct current from solar panels and alternating current from the grid. It uses the solar power when available and complements it with grid power when not. I have one and it works, it runs fully off of 3 300W panels in series (so 900W at around 30-35V DC), and even when it runs off of the grid, it is very efficient. But even that is an inefficient use of the solar panels, so I also store the power in batteries (through a charge controller) and I run 12V DC lights in my house from it. This is a network of 12V LED light fixtures, with their own wiring that I ran through the attic and their own switches. So that uses the solar power to offset some grid usage in my house, but with the cost of batteries and charger, it's still not a cost savings, it's more for a grid alternative backup during extended outages.

If you want to learn more, please visit our website hybrid ac coupled inverter.