Plugging Solar Panels Directly Into An Outlet | Surprising Results

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I found a micro-inverter on Amazon that claimed to be as simple to use as plugging in a standard 120V appliance. This sounded a bit too good to be true so I ordered a unit and put it to the test. I also checked with my local inspector as this does seem to have some areas that might not meet the National Electrical Code (NEC). Overall the results were very surprising and made me think of a bunch of different applications where something like this might come in handy

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[tylerwatt]

The inspector might say it's ok, but it's up to your energy company to approve if this grid tie inverter is allowed to be connected to the energy grid. Typically the energy companies require permits in addition to the UL1741 other certifications, and external disconnects. That said, this setup should be ok, but you may have to conceal it.

If you have a smart meter, these meters can detect energy returning to the grid the moment your energy consumption is below your production on any leg of your house. They will ping your energy company and you will get a threatening letter telling you to remove the equipment or face disconnection.

If you have an analog meter, it's slightly easier to skirt by the rules. Your main issue is the meter reader guy seeing the meter spin backwards (although they probably don't pay attention). The second issue is your usage being negative for the month, which would be somewhat hard to do with small grid tie inverters like this.

The end goal is to make your solar system to produce only enough PEAK energy to meet your IDLE house demands, but nothing more. Once you product more than you consume at any given moment, you'll run into issues.

I'm debating whether to do this, so I can get the solar tax credit, though my roof isn't really oriented the right direction for sun exposure.

[USMC]

Sound to me like this would work well for an RV that is tied into the grid. I’m interested in the follow up videos!

[fox]

Id like to use something like this to power a space heater on a mini closed circuit, that would offset other forms of heating and since home is partially heated by resistance electrical heating benefit would be the same as backfeeding yhe grid but with few/no safety issues or legal issues ultimately the best use would be to heat water in the hot water heater with resistance heating element since the water acts like a battery of sorts storing energy to be used later.

[newbie]

Their instructions say do not exceed 1200 watts of total panel (max of 300 watts/panel), seems like it work with 4 of your over 300 watts panels.

[TexasCanuck]

The title is a bit of a "bait and switch." we all expected you to plug the DC directly into the AC outlet and show us a nice shower of sparks - not happy :(

[CivilRepair]

Thanks for the video. What is the voltage of the AC coming out of the inverter? It needs to be higher than the voltage of the circuit that it is plugged into.

[ranger]

most electric companies measure whichever leg is higher on your meter of power coming into house, so this probably won't lower electric bill much if any since you are only supplying power to one 120-volt leg.

[kris]

I built a home set up with a 600 watt inverter. Y&H from Walmart used a gift card from work so it was only $45. Bought 2 panels 250 watts for 8$5 for both from a solar installer. They where removed for an upgrade or expansion. It knocked $100 of my monthly summer electric bill which can get as high as $380 per month. I have them facing south and at 28 degrees of elevation. Full sun I am getting 370 watts, they are old panels and brand new ones would produce more. I am thinking of expanding with more panels but stay under my grid tie inverters 600 rating. I used a power strip with surge protection where the inverter plugs into my home and have an inline fuse on the power coming in from the panels wired in parallel. I can even install a GFI outlet for the standard one that will cut out if there was ever a power surge from the panels. I used a very small desk fan that is 5 watts to help keep the inverter cool in my garage. It never overheated and overheating is what causes electrical devices to breakdown.

[funnyguylol]

It still breaks code if the baseline load of the home is lower than the power generation, at least in the state of California. You need a utility contract to legally backfeed into the grid.

[junkerzn]

I've got a couple of these sorts of microinverters. Mostly for testing how bad they are. And they do work, but most of them do have major gotchas and issues. Y&H is a major brand for these sorts of things and you are right, there are likely onl two actual OEMs.

* These devices are mostly not current limited. I think they are somewhat temperature limited, but at too high a temperature. If you plug in too much solar they will happily over-produce until something fries.

* These devices have VERY POOR efficiencies. They market high efficiencies but the actual efficiencies are generally around 80%-85%. Very very poor. Real micro-inverters have efficiencies above 97%. And you can tell by how hot these suckers get.

* These devices as sold are often mis-labeled with regards to voltage, power, and current capabilities.

* A 120VAC AC output is just putting power back on one leg... only one of the HOTs coming into the house from the utility (there are two, for 240VAC) is having power returned on it. Of course, you are also limited by the household plug. But still, it is not ideal. So at least try to match what the microinverter is pushing with other household loads that are on that leg.

* YOU CAN OVERLOAD A HOUSE CIRCUIT WITHOUT TRIPPING THE BREAKER. THIS CAN CAUSE A FIRE AND BURN DOWN YOUR HOUSE! How? Lets say you have the circuit wiring with household plugs going from A to B to C to D to the 15A subpanel breaker. Now lets say you plug the micro-inverter into C and you are pushing 1000W. Now lets say that you turn something on at B which eats 1200W. So far so good. The breaker only sees 200W and the B-C segment has 1200W on it. But now lets say you turn something on at A which also eats 1200W. Now the breaker is only delivering 1400W to the circuit but the "B-C" segment of the wiring has 2400W running through it. Bad end.

What this means is that if you do use something like this, either severely limit the amperage it pushes back to the grid (to less than 500W is my recommendation), or ensure that it is on a dedicated circuit. Normally grid-tie inverters are required to be on dedicated circuits.

* These units do not track waveform deformations due to inductive loads very well. From what I can tell, they literally just push a synchronized sine wave instead of doing 4-quadrant matching, so in terms of dealing with reactive power they might be making a mess out of the waveform or they might be overheating themselves trying to work against the reactive power on the waveform without realizing it. So YMMV if you have an A/C system running.

* These devices will operate with line voltages that are way out of spec. They are designed for broad compatibility across several countries. But the high-side of the range they will push the line voltage to is probably too high.

* These units are NOT UL1741 or UL1741SA certified. It isn't even close. UL1741 is the certification required for grid-tie. These units will shut-down if the grid goes down, sure, but not being certified means that these units do not follow safety protocols for grid restarts (for example). Among many other issues.

My conclusion is that for someone just messing around with a few hundred watts, these things do work fairly well. But don't trust them beyond that. Certainly not with the large array you connected that thing to in your example. And be damn careful not to overload whatever circuit you plug them into. Don't share a circuit with a room that someone might plug a space heater into, for example.

[drpgfki]

UHHHH a code issue you say? How about getting sued by your utility for illegally back-feeding to the grid. Doesn't matter if you have RSD (which is also required by code), they are legally required to know about all power production systems, be they 1kW or 1GW, touching the grid.

[lewiskelly]

You should have tested if it turns off when you lose grid power (wouldn't turning off the main breaker stimulate that?)

[totalpropertysolutionsexte]

I’ve got a few similar inverters that I’ve been running a few months on a temporary setup. They definitely shut down a lot from overheating. We’ll see how long they last.

[SkaBob]

I would turn off the main breaker and see if it also shuts down and make sure it doesn't actually continue to output power if the grid is down.

[DastardDek]

Wonder if you could use this with a pure sine wave inverter on a off-grid microgrid instead? or with something such as a bluetti or ecoflow? That way you avoid the possible legal issues that may arise with your power company or other organizations.

[danielking]

Better to use an off grid string inverter on a critical circuits panel with grid input when battery and solar isn’t sufficient. The power is clean and you have100% self consumption. The technology has advanced greatly and is not expensive.

[jeromewelch]

Just plain bad idea!!!! That must be grid tie configured? "If the grid stops, pushing you STOP producing do not connect infrastructure to your home with a plug or receptacle configuration if so, it needs to be rated and designed for continuous operation at the listed rated power plus 50% derating factor.. Receptacles melt!!! Please be safe!

[Pallidus_Rider]

Seems like best use is to charge batteries, then run devices off of the batteries.

Thus no illegal tie in .

[robertgamble]

Does the inverter synchronize the AC frequency with the frequency of the Grid’s power?

[brucej]

I am assuming the circuit MUST sense and synchronize itself to the power grid like expensive systems. However, I have 3 concerns...
Concern 1) I would highly recommend stressing that connecting the way it comes is against the code and could be DEADLY! All you need is a kid (or adult) coming by and unplugging it. I suppose it could be meant to only output if it senses grid power but is that the case???? Just too much risk IMHO. Of course a "regular" male plug is also very dangerous on the house side, so that isn't the answer either. Maybe they make a special no exposed contact connector???
Concern 2) The danger of backfeeding the power grid... I suppose the same safety feature I mentioned for concern 1 MIGHT take care of that in theory?
Concern 3) As someone else mentioned, with both the solar and grid able to supply power, the normal breaker protecting that circuit could in theory supply more than it's rated current... The amount from the breaker AND whatever solar can supply. It should feed a dedicated circuit IMHO.
Thanks for your videos. Please take this as constructive feedback. (Note: I am NOT a licensed electrician.)