Looking for 120v grid tied inverter for shed

[DIYrich]

I have a new shed I can put a few panels. Unfortunately, there is only a 120v outlet within 10 feet I can connect to. Otherwise it is 50 ft to the house, and another 50 feet to the electrical panel.

All the grid tied inverters I see are 240v. Anyone know of a UL listed 120v inverter at a reasonable price?

Will an inexpensive UL listed 240v grid tied inverter handle 15 amps on one line and 0 amps on the other?

I'm guessing an autotransformer would be ok in this situation (no chance of it trying to balance the grid).

Any other ideas?

Thanks.

 

[12VoltInstalls]

So you are basically looking to feedback your main house solar (acting as grid) through the 20A outlet.

Is that outlet feed direct burial / UF or in conduit?

If it’s in conduit I’d pull the existing cable or wires and drag through enough ~10ga or 8ga or whatever’s required (if it fit) for 240 and supply the outlet through the new gridtie inverter/aio/thingy.

That would give multiple opportunities for a solution.

 

[DIYrich]

There is buried conduit from the house to a Post about 10 feet away from the new shed. I don't want to try and figure out where it comes from the house, condition of conduit, etc. in order to fish a new wire. It could easily take multiple hops via the outside sockets.

So, the idea is to bury conduit from the shed to the Post, and feedback the main house from there. Thus limited to a 120v circuit.

 

[AntronX]

Rewire your 120V outlet for 240V and install 240 > 120V step down transformer to regain 120V outlet. You can add a switch so you don't have transformer wasting power when not in use. Just make sure nothing else is branched off from that 120V outlet line or whatever else is connected to that line will be fried. There are no 120V UL inverters that I know of, only cheap low quality stuff.

 

[cs1234]

Do you already have an agreement with the utility allowing you to do feedback?

If you do, and they aren't going to knock down your door about feedback.. just use a 120vac grid tie inverter with limiter. You wouldn't need the limiter part, it is a nice little wattage display though, if you want to monitor a circuit. Sadly, there is no UL listing.. nor will there ever be for this class of product.

I can vouch for this one working well enough. The first one I ordered, I was accidentally shipped a 240vac model instead of 120vac. It worked on 120vac.. but would complain about low AC voltage and drop out sometimes. Just make sure the screen shows 120vac on it when you hook it up and turn it on. Everything worked much better once they sent the 120vac one.

 

[12VoltInstalls]

There is buried conduit from the house to a Post about 10 feet away from the new shed. I don't want to try and figure out where it comes from the house, condition of conduit, etc. in order to fish a new wire. It could easily take multiple hops via the outside sockets.

Uggh!

So, the idea is to bury conduit from the shed to the Post, and feedback the main house from there. Thus limited to a 120v circuit.

I’d be inclined to dig a new trench and do something fresh and appropriate for the 240 circuit. If it’s only 50’ because you can bump through and run the rest inside. Especially if it was going to pay me back

 

[DIYrich]

Do you already have an agreement with the utility allowing you to do feedback?

If you do, and they aren't going to knock down your door about feedback.. just use a 120vac grid tie inverter with limiter. You wouldn't need the limiter part, it is a nice little wattage display though, if you want to monitor a circuit. Sadly, there is no UL listing.. nor will there ever be for this class of product.

I can vouch for this one working well enough. The first one I ordered, I was accidentally shipped a 240vac model instead of 120vac. It worked on 120vac.. but would complain about low AC voltage and drop out sometimes. Just make sure the screen shows 120vac on it when you hook it up and turn it on. Everything worked much better once they sent the 120vac one.

I have a sol-ark connected that can feedback the grid, so i'm good there.
I am hoping for UL1741 so the Sol-Ark can frequency shift if need be.

 

[DIYrich]

I’d be inclined to dig a new trench and do something fresh and appropriate for the 240 circuit. If it’s only 50’ because you can bump through and run the rest inside. Especially if it was going to pay me back

When I dig a hole to plant a bush, about 1/3 of the hole is rocks. I can survive digging down 6 inches (RMC) for 10 feet. I get a headache thinking about 50 feet, and the cost of 50 feet of RMC. Running wire in the house is also a pain (but at least doable). The 15 amp circuit is the max for the shed. If I could put more panels, then a new run would be the way to go.

 

[cs1234]

I have a sol-ark connected that can feedback the grid, so i'm good there.
I am hoping for UL1741 so the Sol-Ark can frequency shift if need be.

The one I mentioned with the limiter can work in place of frequency shifting support. Just put the limiter on it so it knows how much to limit it.. it doesn't run full blast all the time like a microinverter if you tell it to use the limiter.

The downside is the limiter needs to be installed somewhere it can actually sense some current. The positive part is, it uses a cable type where you can just sub out the cable for some RJ45 and it works fine.. hundreds of feet. Downside again though, you have to run RJ45 cable to it for the limiter to work.

 

[sunshine_eggo]

UL1741 may not be necessary, but that functionality might be. I have one of these:

https://www.amazon.com/gp/product/B00XJCVC44/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

That specific one isn't available, but there are lots more like it. I've been using it for 6 years for a non-PV backfeed application.

It claims anti-islanding, and I've confirmed I can unplug it from the socket and check for voltage at the cable pins and get 0V. However, what I don't know is if the typical <2Hz frequency shift is enough to trigger anti-islanding.

 

[DIYrich]

The one I mentioned with the limiter can work in place of frequency shifting support. Just put the limiter on it so it knows how much to limit it.. it doesn't run full blast all the time like a microinverter if you tell it to use the limiter.

The downside is the limiter needs to be installed somewhere it can actually sense some current. The positive part is, it uses a cable type where you can just sub out the cable for some RJ45 and it works fine.. hundreds of feet. Downside again though, you have to run RJ45 cable to it for the limiter to work.

Limiter sensor (ct?) would have to be at the house. Too far away, unless it is internet connected sensor.

 

[cs1234]

Limiter sensor (ct?) would have to be at the house. Too far away, unless it is internet connected sensor.

Yeah, it's an rs485 sensor. There are all sorts of rs485 extension devices you can get, some of which use ethernet/wifi. I'm sure others here on the forum could steer you in the right direction. Supposedly it can support distances into the thousands of feet and still work without ethernet, but I've never tried it or make such guarantees.

However, the way this sensor works, it wants the power being injected by the inverter to be ahead of the sensor. If you inject the power under the sensor, which is how you would have it done, it only injects up to half as much power as it detects because the load detected by the sensor decreases by the amount being injected.. it fights itself. I have mine hooked up that way, because I don't care, and it works well enough for my needs, but it's amusing to watch. I'm powering mine with batteries charged by a separate mppt though. I'm not trying to use as much solar at all times from it as I can, I just save it for later and inject it slowly over time.

I don't think it would cause problems any problems with the Sol-Ark though.. if there is a load past the Sol-Ark that the sensor detects, it will inject to power it. If it detects no load, it won't inject. Whether running grid power, or Sol-Ark inverting, I think it would be ok. Ain't got nothing to lose but a Sol-Ark..