Choosing Correct Grid Tie Inverter

[chiques]

Hello Community,
I recently purchased two Canadian Solar CS6P-250P panels in order to begin a scaleable grid tie system for my home. I found a couple of LT-SunD-250G (http://www.chinesegrid.com/Solar-Gri...N-250G433.html) Tie Power Inverters on Ebay and bought them.

What I found when I mounted and ran all my wiring is that if the tie grid inverter is rated from 10.8 to 30 VDC input, THAT IS ALL IT WILL ACCEPT. My panel is pumping out at between 33-34V on an open circuit. The SUND-250G's barf and immediatly go into a default mode.

I ended up tapping off the single panel and adding a solar charger (to reduce the voltage without ruining my efficiency too much). It works, crappy, but it works. My panel is feeding about .45A @ 120VAC and about 1.2A @ 12VDC to charge my battery.

I'm going to end up scrapping this design and move foward and purchase an inverter which supports the higher input voltage. My budget is about $150-$200 USD. I saw that Amazon has http://amzn.com/B005N2B0C2 for about $175. Does anyone have any feedback on this or any similiar to them?

I also noticed that Power One and Enphase make some around this price range (http://www.affordable-solar.com/stor...ters-grid-tied) but they are all 200VAC (three phase). This would require some more infastructure and defeat my design goal of a cost efficient system.

Any guidance will be greatly appreciated.

[SunEagle]

Hello Community,
I recently purchased two Canadian Solar CS6P-250P panels in order to begin a scaleable grid tie system for my home. I found a couple of LT-SunD-250G (http://www.chinesegrid.com/Solar-Gri...N-250G433.html) Tie Power Inverters on Ebay and bought them.

What I found when I mounted and ran all my wiring is that if the tie grid inverter is rated from 10.8 to 30 VDC input, THAT IS ALL IT WILL ACCEPT. My panel is pumping out at between 33-34V on an open circuit. The SUND-250G's barf and immediatly go into a default mode.

I ended up tapping off the single panel and adding a solar charger (to reduce the voltage without ruining my efficiency too much). It works, crappy, but it works. My panel is feeding about .45A @ 120VAC and about 1.2A @ 12VDC to charge my battery.

I'm going to end up scrapping this design and move foward and purchase an inverter which supports the higher input voltage. My budget is about $150-$200 USD. I saw that Amazon has http://amzn.com/B005N2B0C2 for about $175. Does anyone have any feedback on this or any similiar to them?

I also noticed that Power One and Enphase make some around this price range (http://www.affordable-solar.com/stor...ters-grid-tied) but they are all 200VAC (three phase). This would require some more infastructure and defeat my design goal of a cost efficient system.

Any guidance will be greatly appreciated.

Besides the fact there was a really bad review on that item it would be illegal to install in anywhere in the USA because it does not meet the Electric Code and worse is dangerous.

The only allow "grid tie" inverters are those that are hard wire connected to the main house panel using proper wire and circuit breakers. Anything that "plugs" into a house receptacle is not legal and at worse dangerous due to potential circuit overload, shorting and fire. Please do not purchase one of those type inverters. Go with a Power One or something similar in quality.

[chiques]

That's great feedback and I appreciate it. I live in California so you could only imagine our extreme code enforcement. I have experienced applying for city permits and having the city inspector approve phases of my home improvements. I also welcome it and find it very helpful to get things done right and safer. As a matter of fact, one of the first things I did when we purchased our 1949 home is rip out all the old obsolete oxidized wiring along with the main electrical box and upgraded it all up to up to date industrial grade equipment (including a 200A panel) with help of a well trained electrician. If I recall correctly, I even had our local electrical company replace the wiring coming from the power lines to our home- all with brand spankin new copper wire.

I can't really find anything that classifies a devices that is not hard wired as requiring a permit. I'm well aware of any addition or structure attached to my home requiring a permit. Also (as mentioned above) any electrical work needs a permit. I will call my city permits division and get their take on it.

I have my inverter in one of the furthest places away from the main. I'm curious to see statistics or some other metric to give me an ideal on how 'bad' / 'dangerous' my project really is. I ran into this article (http://www.homepower.com/articles/so...tie-connection) and aside from a couple of building codes, the real danger comes down to the qualify of the wire (in my case I have a 10 gauge/ 100ft feed from the main- about 5 years old, underground) and the type of reactive equipment loading that specific circuit. It appears that power generation could stress the circuitry (e.g. breakers etc...) triggering false negative faults causing the breaker not to - break. I can see this leading to heat -> ignition ~ fire. But, I don't have any of that stuff on this circuit.

I got a little freaked out when I firs read this response so I also searched the National Fire Protection Association for the main causes of structural fires. It appears this awareness should be focused on cooking equipment more than grid tie inverter type of equipment. According to the report attached below there were approximately 157,300 fires (2006-2010) where cooking equipment was involved. They had some statistics on photo voltaic fires (see attached) but they all appeared to ignite around the panel itself. They appears to be concerned more on having a main shut off in the event of an emergency. This is something I will install immediately.

If I'm going to invest -again, in the correct inverter. I will definitely take a second look at the Power One or the Enphase products.

Thank you for the feedback.


Sources:

http://www.nfpa.org/

[SunEagle]

The problem resides with the type inverter you were looking at. They are manufactured in China where quality control is not high on the list of responsibilities. The internal parts may not even be properly wired with potential of shorting out.

The other issue is that your house receptacle circuits were designed to provide power, not receive it from another source. The over current protection for that receptacle is in the main circuit breaker panel and not in the inverter where is should be since it is the source of power.

Also there is no guarantee that the "anti-islanding" circuit (which is supposed to shut the inverter off in the event of a grid power failure) will work properly thus exposing the Utility electricians to potential electrical shock when the work on the wiring in the street.

I can continue with the inverter faults but I think you get the idea. Only a UL listed inverter that is installed by a licensed electrician can be connected to your house panel. There also needs to be approvals from the Utility to make that connection.

Final thought for the day. If you used a non UL listed device in your home and it caused a fire would your insurance company cover your loss?

[Sunking]

The inverter cannot be used because it is not Listed.

[extreempv]

I understand that you want to have a scalable system over time, but please don't use these ebay inverters!

Your spending good money on descent panels and then bodging the electrics to try and make it work.

If you are looking at scaling this over time, then look at micro inverters. They will allow you to add panels as budget allows and also enable different panels to be used - if your current model is superseded.

I'd suggest Power One Micro Inverters over Enphase, as they have 250W + 300W versions, and also a wider input voltage range.
There is also the new SMA micro inverters available, but the Power One gives the greatest flexibility for panel selection in the future.

With micro inverters (Power One / Enphase / SMA) you will get monitoring for individual panels.

Micro inverters are not the cheapest option, but for a system scalable over time its the best option.
I don't know how Building Codes go for installing over time - You may be able to get an electrician to install the first micros + AC trunking and cap the AC trunking for future expansion. I don't know if you would be allowed to add the additional micros at a later date or require your electrician to do that? Whatever way you do it..please make sure its safe.

Ken

[chiques]

I understand that you want to have a scalable system over time, but please don't use these ebay inverters!

Your spending good money on descent panels and then bodging the electrics to try and make it work.

If you are looking at scaling this over time, then look at micro inverters. They will allow you to add panels as budget allows and also enable different panels to be used - if your current model is superseded.

I'd suggest Power One Micro Inverters over Enphase, as they have 250W + 300W versions, and also a wider input voltage range.
There is also the new SMA micro inverters available, but the Power One gives the greatest flexibility for panel selection in the future.

With micro inverters (Power One / Enphase / SMA) you will get monitoring for individual panels.

Micro inverters are not the cheapest option, but for a system scalable over time its the best option.
I don't know how Building Codes go for installing over time - You may be able to get an electrician to install the first micros + AC trunking and cap the AC trunking for future expansion. I don't know if you would be allowed to add the additional micros at a later date or require your electrician to do that? Whatever way you do it..please make sure its safe.

Ken

Hello Ken,
Your comments seem to be the most sincere and accurate I could find from the thread. Thank you for the clear and concise words.

I have decided to disable my panels for the moment but for a different reason. I guess the fact that I was using speaker wire did not make things any safer. I've dealt with speaker wire melting the non-UL certified insulator before on other science projects. I was monitoring my panels on a very hot dry sunny SoCal day and I noticed the wire I had ran (which was stapled to the wooden rafters I might add) was heating up. That immediately set off all my experience alarms and prompted me to shut the system down until I least get a heavy gauge UL approved DC wire.

From what I've learned in all the chewings and good advise on this thread are 3 main things that are a must to maximize the safety of my installation.

1. Tap directly into the 3-phase 220V line at my meter box with adequate gauge wire on my panel rail
2. Use heavier guage UL approved wire- always
3. Use a reputable inverter, to maximize efficiency and circuitry

[inetdog]

Hello Ken,
Your comments seem to be the most sincere and accurate I could find from the thread. Thank you for the clear and concise words.

I have decided to disable my panels for the moment but for a different reason. I guess the fact that I was using speaker wire did not make things any safer. I've dealt with speaker wire melting the non-UL certified insulator before on other science projects. I was monitoring my panels on a very hot dry sunny SoCal day and I noticed the wire I had ran (which was stapled to the wooden rafters I might add) was heating up. That immediately set off all my experience alarms and prompted me to shut the system down until I least get a heavy gauge UL approved DC wire.

From what I've learned in all the chewings and good advise on this thread are 3 main things that are a must to maximize the safety of my installation.

1. Tap directly into the 3-phase 220V line at my meter box with adequate gauge wire on my panel rail
2. Use heavier guage UL approved wire- always
3. Use a reputable inverter, to maximize efficiency and circuitry

Regarding item 1, that is not a DIY job under any circumstances. Connecting to a dedicated circuit 240V breaker is not technically DIY either but it is a lot safer than trying to connect on the meter side of the main breaker!
If you went ahead and used speaker wire without knowing in advance what current it could handle you should not be going anywhere near your breaker panel without help from a licensed electrician. This is for your own good and the safety of others!

PS: The fact that you even mention 3-phase 220 in this context indicates to me that you do not know what you are talking about.

[OregonSolar]

That inverter is a piece of shizz. Period. You're better off spending your money on a bucket of liquidized cow shizz to put on your lawn than that.

Note it says AC VOLTAGE: 90-130. Means that it will probably be putting out 100V at any load, making lightbulbs dim and can fry some sensitive electronics.

this will cause major problems right out of the box ranging from killing your TV hooked up to it from under voltage to turning your house into a smoking ruin. PLEASE do not ever ever get this!!!

Oh, and BTW: Talk to an electrician. NO domestic power supply is 3-phase, that is industrial power. You might have 220V for your dryer, though.

[inetdog]

Oh, and BTW: Talk to an electrician.

That is the most important thing the OP can do, bar none. I take that back, the best thing the OP could do is just give up on the idea.

NO domestic power supply is 3-phase, that is industrial power.

Actually not strictly true. The distribution wiring will still be 3-phase within POCO, so whether the residence gets single phase or 3-phase will depend on the custom at the time. In some parts of the country the biggest feed to the house was from a single center tapped transformer to produce 120-0-120, three wire. But a second transformer on a different primary phase would be wired in just to drive the older AC units that really liked three phase power. (High leg open delta)
If you say almost none, I will happily agree with you.
But if it is instead a complete three phase wye and a recent installation, it will much more likely be 3 phase 208Y/120 than anything with 240. And it would be an exceptional McMansion that got that kind of service supplied.
220V is not really a standard voltage in the US. Just like 110.

[OregonSolar]

That is the most important thing the OP can do, bar none. I take that back, the best thing the OP could do is just give up on the idea.


Actually not strictly true. The distribution wiring will still be 3-phase within POCO, so whether the residence gets single phase or 3-phase will depend on the custom at the time. In some parts of the country the biggest feed to the house was from a single center tapped transformer to produce 120-0-120, three wire. But a second transformer on a different primary phase would be wired in just to drive the older AC units that really liked three phase power. (High leg open delta)
If you say almost none, I will happily agree with you.
But if it is instead a complete three phase wye and a recent installation, it will much more likely be 3 phase 208Y/120 than anything with 240. And it would be an exceptional McMansion that got that kind of service supplied.

Thanks for correction, but still, would seem somewhat odd. I was basing that off of my experience with my dad's weld shop at the state university, which has a 200A 480 3-phase drop for the massive hydraulic stress testing equipment and a 40A circuit of ventilation in there, plus about 10 big welders run off of a separate 208 drop.

220V is not really a standard voltage in the US. Just like 110.

Same difference. My electric dryer is rated at 220V, but my oven is rated for 240. Seems to really just to vary on what manufacturers use to actually test their equipment.

All in the margin of error, right?

[Naptown]

220 221 whatever it takes.