Power From Solar During Grid Power Failure

[JustinSolarGuy]

You are talking about trying to Trick the inverter into thinking the grid is still on. I don't think this is a good idea. If your UPS is a modified sine wave type then the SMA will probably have problems recognizing this power; it may damage the inverter. You will need to talk with an Electrical Engineer. I am no Engineer but I know this basic truth. Its always a bad idea to use the wrong tool for the job.

The Grid tied inverter you are purchasing is specifically designed to not do what you want it to do. If you really want power from you solar panels during an outage you need to buy a battery based grid tied inverter. This will cost you about 10% in system efficiency and you will need to buy batteries, a battery box, and a charge controller plus you will need to separate you critical circuits onto a smaller sub panel for energizing when the grid goes down. You will pay a lot of money for the luxury of power during the odd outage.

Another option if you want to mess around with a grid tied system that you already purchased is to put in an A/B switch and steal your DC solar power before it gets to your Grid tied inverter. You can have a qualified Electrician tap into the feed from the roof. Now you have to figure out what to do with 200-500VDC. Look for a battery based inverter or charge controller than can handle this voltage not sure if they exist. You can run DC water pumps or other motors. Possibly certain light bulbs. That's about it.

Or you could put in a few A/B switches in the array wiring and steal your power from the individual modules or pairs of modules before they get strung together in the array. Now you have the option to just steal two, four, or six panels and you can definitely find a charge controller and inverter that will run on the voltage of two panels in series. Of course these systems are manual and you would only implement this if you already had a grid tied system and just couldnt stand the thought of wasting all of your solar energy during an outage. Also, you will need to somehow get this power to the appliances, the safest way would probably be to roll out some extension cords or to have a licensed electrician separate some circuits in the appropriate manner.


If you are worried about the end of civilization as we know it, and you will want to take advantage of your solar energy at that time then you only need to buy some batteries, a float charger, a cheap non grid tied inverter, some extension cords and a charge controller. Throw the batteries on a float charge somewhere safe and leave the rest in a box in your garage. When the the big whatever it is hits you can rewire your panels to charge the batteries and run whatever you want off of the inverter. But this would not be practical for the odd utility outage.

But honestly the importance of instant automated backup power for your home is greatly overestimated by the average consumer in most cities. Just buy a UPS for your computer and get a Generator to run your fridge. Plus you can take the generator camping or bring it along on the exodus to the promise land after the big whatever it is hits. You aren't going to bring your 800 square foot array along... that's for sure.

[woltnj]

I understand why the power is cut off, I want to keep the power cut off from the grid but want to have the solar panels still power my house.

[indalecio.feng]

This is a special function for the inverter, in case someone does some work on the powerline which connect to your home and will not hurt by your SHS AC output to the powerline.

[woltnj]

I am getting a new 8.8kW Solar installation done over the next couple months. There is one problem I am trying to solve. When the system is installed with SMA inverters, it will have a DC and AC cutoff so when the grid power goes the solar will be shut down. What I am trying to figure out is how to keep the solar generating power for my house while cutoff from the grid during the power failure. Is the cutoff done purely as a safety measure for the power companies or is it something technical with the way the inverters are designed that they need the grid power to function.

I was thinking about getting a 220v UPS to plug into the house AC to provide power to the inverter while the grid power is disconnected thus keeping the solar generating power to the house. I know there are expense battery solutions that people use but I do not want to store enough power to run the house, I just want to generate power during the day if I lose power from the grid.

Thanks