seeking opinions on micro grid tie inverter

[terracore]

This is not your UL listed type of micro-inverter:

http://www.amazon.com/High-frequency-Solar-Grid-tie-Inverter-Converter/dp/B00RWYXVC6/ref=sr_1_4?ie=UTF8&qid=1440649288&sr=8-4&keywords=MICRO+GRID+INVERTER

That particular model was just sort of chosen at random because I haven't done any research on them yet. But for those of you who don't want to click the link its for low wattage solar panels to convert their output into a pure sine wave and contribute to your household current by plugging into a wall outlet. Before you freak out the "good" ones automatically quit feeding if grid power cuts out so you're not feeding the grid.

The reason I am looking into this is I have a few 100 watt panels that I use to charge a deep cycle battery but I don't need to charge it very often. So rather than sitting there doing nothing if the panels can knock a few dollars off my bill each month...

If you want to start venting about zoning, codes, and the like then by all means please start your own thread and do it there. I already have a pretty good idea what HELCO, the fire marshal, code inspectors, and random lunatics would think of a product like this and don't need to read it again here.

[leilanidude]

I can see where you are going with that. I clicked on a few others that popped up that have better "english descriptions". My only concern would be what happens if your grid power goes out? It would be back-feeding the grid?

[kalakoa]

I'll skip the code issues because I hate HELCO more than I hate County.

It is possible to "get away with" backfeeding the grid **IF** you have a dumb mechanical meter -- newer electronic meters can (will) detect the backfeed.

Practical reality is that your house will probably just eat the first few hundred watts before the grid even sees them.

As far as safety, most of these microinverters do implement both sync and auto-island.

Surprised they're on Amazon, though; these are far more common on eBay.

[ericlp]

My thoughts...

I guess what this device does... is... take something that is ran in the daytime time only like say an attic fan. Or maybe a cell phone charger, cordless phone. etc... When the sun is shining it will run the device full load, and when it is cloudy, and say it could only juice up half the load, would it adjust itself on the fly to maintain half solar and half grid power? So if you plugged this into a fridge it's obvious that this would never have the capacity to run a fridge, but, it could maybe run one at 1/3 power savings when the sun is out and the mains picking up the slack of the 2/3's.

Is that pretty much what this device does? Kinda like a charge controller and an inverter and a power monitor all in one? Seems like a lot is going on in this unit for 100 bucks. I suppose if you had a 1000 watt unit you could be saving some cash, that is as long as the sun was out shining and you used all your devices in the daytime, as obviously without batteries this thing will do nothing for you at night.

Next... it could be chinese crap. It's getting better but still iffy. I dunno, I suppose when it faults out, you could come home to a fridge without power. or if you had a computer or tv connected to it, how well is the "pure sign wave" ?? For 100 bucks can you really trust it? Or do you just put this on a bunch of box fans around the house to keep it cool when the sun shines? Then if it burns up and takes a few fans with it, you won't be out much money.

Then again, you could always buy an outback inverter and a midnight charge controller, hook em up to the batteries, panels you got, run the fridge and add more later. Spend some money now, that is upgradable, on reliable quality equipment, or spend less money on something that is questionable reliable and non upgradable. I guess that is your question?

I guess if you have a 100 bucks to burn, some time on your hands, try it out! Let us know how it works out for you!

Me personally? I kept my eye open on C/L and timed it just right, got 8 L16 batteries, 2500 watt pure sign wave 24V Outback inverter and a midnite classic charge controller + boxes, switches, fuses, shutoff breakers, All the heavy battery cables and wiring etc...etc... for 3K cash and less than 6 months old. All I need now is another 2K in panels and I'm pretty much set.

I know deals like that don't appear that often, but I did it! I've always thought about getting off the grid, and pondered chinese inverters, and have heard all the stories... I want to lessen my risk of waking up one day to a dead inverter or charge controller and having to start the generator to keep the food in the fridge cold. I am a bit excited about it, and with real professional equipment the dream is turning into reality.

Tho, I have friends that are running colman cheap inverters etc...etc... and that seems to be working for them. Maybe the quality is getting better on the cheaper made in China units. Still it's a personal decision. To each his/her own!

[Jeremy Lutes]

If I were to try one of these micro-inverters, I'd also want some way of metering (monitoring) the AC output, so I could verify that it's working as desired. Something like the Kill-A-Watt meter, which you'd insert between the inverter and wall outlet, so you could measure watts being fed into the AC line.

I'm not certain that the Kill-A-Watt can be used in this way, as it might only be able to measure watts OUT of the outlet, but here's a video of someone using a similar meter to monitor output of a microinverter: https://www.youtube.com/watch?v=RNHZLEi6gvA

If you're comfortable working with AC wiring, you could cobble together a monitor of your own using something like this:
http://www.ebay.com/itm/AC-80-260V-LCD-D...1e9eec0a35

I only mention all this because it might be hard to get an idea of how much the PV panels /inverter combo are helping your utility bill based solely on the bill, given the variability sunlight and daily power usage.

[kalakoa]

Kinda like a charge controller and an inverter and a power monitor all in one?

Grid-tie. Auto-island. Not standalone.

[terracore]

To clarify, the way these products work is that they convert the power from the panels using an inverter that plugs directly into a wall socket. ANY device on the single phase circuit can use the power made by the device, therefore less energy comes from the grid. The micro inverter doesn't power anything directly, it's just adding its juice to the grid juice. Since its on "this" side of the meter, the POCO is left unawares. In my house with UV sterilization unit, fridge, freezer, and phantom loads etc two 100 watt panels are never going to produce more power than what the house uses just sitting there, so there is no possibility of producing more power than is being used. These micro inverters sense the grid power and are supposed to shut off if grid power goes down, so as not to backfeed. They also put themselves into a sleep mode when its dim or dark so the inverter isn't trying to convert power that isn't there (I have read that their phantom load is about a half watt).

I have seen people using a kill-a-watt unit with these to see how much power is going into the house (apparently the kill-a-watts work regardless of which direction the power is flowing). I don't know much about the killawatt but in measuring energy over time its probably going to measure the dark phantom load and add it to the sunny producing load so maybe hard to know for sure how much energy cost is being offset, but lets face it a half watt is probably statistically insignificant.

All of these units are Chinese construction. I would use a kill-a-watt (or similar) to determine if the $ energy produced ever amounts or exceeds the cost of the unit.

[Obie]

I use an inverter like that at Christmas time to power the 115 volt lights on our golf cart.

It's not built to do anything more than that !!

[danl]

We had a solar array professionally installed. They used these:

https://enphase.com/en-us/products-and-s...oinverters

We are not on island (yet), but their products are.

Enphase is a reputable local business. I do not know what they cost or where you can buy them. They sync the AC to the line and shut down when the line drops. They have a good web site with a lot of information. I'm very happy with their products.

For power monitoring you might look at:

http://www.theenergydetective.com/

Might be overkill for you; but also has a lot of useful information.