Micro Inverter for single-panel DIY installation

[sheep]

Hi everyone!

I have a single 250W solar panel, which is currently operating off-grid, charging up a bank of batteries. It is not ideally located, and only receives direct sunshine for part of the day - most of the day it is shaded, and generating only about 30-40 watts. I'm thinking about replacing the charger with a grid-tie inverter to make more use of the generated power. 30-40 watts would be sufficient to power my entire house (fridge excluded) most of the day.

It it possible to buy a micro inverter that can operate completely stand-alone, and does not require any kind of gateway or management unit to configure it?

I believe the old first-generation Enecsys units can operate stand-alone, but the Gen2 units require a management unit to enable them. Similarly the Enphase inverters require their (stupidly expensive) Communications Gateway unit to enable them.

I have spoken to a local solar installer, and he says that the Enphase gateway is only required for initial setup and can then be removed from site. However, I would worry about the inverter somehow losing its configuration at some time in the future, and I would be unable to re-enable it.

The price of the Enphase gateway is prohibitive, and would cost double the whole of the rest of the system including the solar panel, and wipe out any possible savings in electricity.

There are cheap Chinese ones available on eBay, but I was really looking for something good and reliable. Can anyone advise?

Annoyingly, a lot of inverters on eBay are described as "micro inverters" but are actually just normal grid-tie inverters and require quite high input power to initialise, and will not work with a single panel. I know because I bought one, found it to be useless, and sent it back.

Thanks in advance.

[kwilcox]

Enphase micro inverters don't require the gateway to operate or set up. The ones that I'm familiar with are grid-tie only however.

[sheep]

Enphase micro inverters don't require the gateway to operate or set up. The ones that I'm familiar with are grid-tie only however.

That's not what I was told by Enphase Energy Technical Support.

Here's their reply to my query:

Hello (sheep)

The micro inverters we make do required to the Envoy communications gateway to commission the system but once they are up and running you can then remove the Envoy and use this to set up multiple systems.

If you have any other questions please just let me know.

Best Regards,

Richard Tullett
Enphase Energy
Customer Support Technician

This was also confimed by my local dealer, who told me that the micro inverters will not start until they have been configured by the gateway.

[SunEagle]

If you live in the USA you will not be able to connect a single 250watt panel even using a legal UL listed grid tie inverter. Most grid tie systems are a bit larger and require approvals from the local Utility and code enforcers.

The Utility will also not approve any of those cheap inverters that "plug into" a house receptacle. Those are not UL listed, usually junk and will fail or worse cause fires.

The problem you have is the shade hitting the panel. It might be more beneficial to find a better place so it gets more sunlight.

[sheep]

If you live in the USA you will not be able to connect a single 250watt panel even using a legal UL listed grid tie inverter. Most grid tie systems are a bit larger and require approvals from the local Utility and code enforcers.

The Utility will also not approve any of those cheap inverters that "plug into" a house receptacle. Those are not UL listed, usually junk and will fail or worse cause fires.

The problem you have is the shade hitting the panel. It might be more beneficial to find a better place so it gets more sunlight.

I don't live in the USA.

The "plug-in" type inverters are not true micro inverters, even though they are often described as such by their sellers - they will not start on a single 250W solar panel even in full sun - I know, I've tried. It attempted to start, immediately dragging the panel voltage down, then cut out almost instantly, only re-trying several seconds later. I left it connected to the panel in full sun for several hours and it never managed to start. They are designed to be connected to a larger array. A true "micro inverter" designed to be attached to a single panel should give some usable output even when the panel is shaded.

The problem is not the location of the panel - it's finding a genuine micro inverter that will operate without requiring a very expensive communications gateway to enable it.

[SunEagle]

I don't live in the USA.

The "plug-in" type inverters are not true micro inverters, even though they are often described as such by their sellers - they will not start on a single 250W solar panel even in full sun - I know, I've tried. It attempted to start, immediately dragging the panel voltage down, then cut out almost instantly, only re-trying several seconds later. I left it connected to the panel in full sun for several hours and it never managed to start. They are designed to be connected to a larger array. A true "micro inverter" designed to be attached to a single panel should give some usable output even when the panel is shaded.

The problem is not the location of the panel - it's finding a genuine micro inverter that will operate without requiring a very expensive communications gateway to enable it.

I understand. Good luck finding the inverter. If you do bring back the data so others may know.

[sheep]

I understand. Good luck finding the inverter. If you do bring back the data so others may know.

Of course, I will report back if I find anything

The only one I have found so far is a cheap Chinese one on eBay (item number 191276952174 for example). It appears to be a "real" micro inverter, but it's probably rubbish.

As mentioned above, the Enecsys (Gen2) and Enphase micro inverters cannot be enabled without a communications gateway.
Enecsys Gen1 micro inverters are factory-configured and will work without a gateway, but are no longer available.

[sdold]

That's not what I was told by Enphase Energy Technical Support.

Here's their reply to my query:



This was also confimed by my local dealer, who told me that the micro inverters will not start until they have been configured by the gateway.

My 16-panel Enphase M215 microinverter system put out nearly full power the first day I fired it up, as confirmed my my smart meter. I hadn't even taken the Envoy gateway out of the box yet.

[sheep]

My 16-panel Enphase M215 microinverter system put out nearly full power the first day I fired it up, as confirmed my my smart meter. I hadn't even taken the Envoy gateway out of the box yet.

Hmmm. Maybe they are factory-configured for use in the USA, and need to be reconfigured by the gateway for use in other countries? I'll ask Enphase.

[kwilcox]

Good idea. I never even bought a gateway for mine. I use a TED 5000 to monitor output. I can pm you a link to my array construction journal if you like since I can't post it here. Its a pictorial journal that shows how my array was built.

[myfriendSUN]

My 16-panel Enphase M215 microinverter system put out nearly full power the first day I fired it up, as confirmed my my smart meter. I hadn't even taken the Envoy gateway out of the box yet.
The same thing happened to my 32-panel Enphase M250 sytem.
I was not at home on the day the utility came to replace their meter with a bi-directional one.
My wife turned on the system right after the meter replacement.
When I got home after work I found out that 15KWh were pushed back to the grid already.
The Envoy was NOT installed yet.

[sdold]

[B]When I got home after work I found out that 15KWh were pushed back to the grid already.
The Envoy was NOT installed yet.

It's a pretty good feeling, huh? Like a truck has just dropped off a load of money in your driveway. You have to try to forget that the load of money is only a dollar or two, and that you've already paid for the truck, but it's still a good feeling.

[Sunking]

Gateways are an upsale item and not needed. It is just a ball and whistle to get deeper in your pocket.

[myfriendSUN]

but it's still a good feeling.
This is very true.

Gateways are an upsale item and not needed.
This is my most favored part. I can see my panel performance online at any time as far as my best friend SUN is out there.
If you don't need monitoring and analysis functions you don't the gateway.

My system made 13.2 KWH today up to 1:20PM.
The only thing I cannot see is the net meter reading.
It would perfect if I can see that from the gateway.

[sdold]

Gateways are an upsale item and not needed. It is just a ball and whistle to get deeper in your pocket.

Especially if you pay for the "Enlighten Manager" monitoring at $249, which I as the installer luckily didn't have to pay for. The Envoy gateway was fun for a week or so as I showed my friends and neighbors how I am generating "free power", but after that it became about as interesting as a new water softener or any other home appliance, which is what my system really is, after all. It will be great for troubleshooting, but a stick with a mirror is a lot cheaper.