Enphase Mico Inverter

[billvon]

I can't say the were degree'd or not but you just don't want to challenge someone in the commissioning process

Good plan!

For what ever reason they were discussing DC from roof panels and the fact that firemen were concerned for what ever reason. This was a discussion they were mumbling about. I also heard them say something about marking DC conduit every 10' may be a requirement etc. Not sure why but?

Because in most installations you can't disconnect the DC array at the panels*. That means that if a firefighter wants to cut through a conduit to get access to a hole in a roof, if it's DC he might end up with a non-extinguishable arc at the end of the conduit. And if he manages to touch them in the wrong order he could get fried.

That's not exclusively a DC problem; that would be a problem with any power source that can't be easily shut off. With DC it's a bit more serious because a) your body's reaction is all wrong (DC makes you seize up, not jerk around like AC does) and b) with DC the arc is a lot harder to extinguish, since current flow doesn't stop 120 times a second. Thus labeling the conduit "DC" tells a firefighter that he might be dealing with a power source that won't get shut down by pulling the breakers, and might just result in a pretty nasty permanent arc.

DC presents some additional problems as a means of distribution compared to AC. For one, it is harder to extinguish arcs, so switches and circuit breakers have to be designed differently, with greater gaps and in some cases blowout magnets. For another it poses a somewhat greater risk of electrocution because of the aformentioned reaction to DC compared to AC. But there's a reason that people are slowly switching to it for applications where efficiency and cost matter - it lets you send more power down the same copper than AC does.

(* - a segmenting combiner avoids this problem but is not common in PV installations.)

[russ]

I agree - but the "engineers" they send out to commission solar power systems are typically not the people designing HVDC power transmission systems.

Engineers commissioning a residential solar system? I doubt these guys ever have or ever will design much of anything and I doubt any university degrees are involved.

One should certainly not be scared to ask about the background of someone doing work FOR you.

On an industrial basis, not to question is stupid. Often the field men are that just to get the clowns out of the office.

[Sunking]

On an industrial basis, not to question is stupid. Often the field men are that just to get the clowns out of the office.

Russ that may apply to some sectors but not the electric utilities. I started my career working for a POCO and do a lot of contract work for them now and the field people are highly trained to do what they do. There is just too much risk and liability involved. Even Meter Readers have to be trained and require 1-week per year CE. Most technicians are at least 2-year Associate Degrees and many are 4-year BSEET. Typically it requires a minimum of 3 to 5 years of OJT before a Technician is even allowed to go out on their own and run a job.

[russ]

OK - Electrical in the US is more strict but sending an engineer or actually 2 (with 4 year degree) to commission a residential solar setup?

Someone saying he is an engineer has no meaning.

The POCO wasn't commissioning anything anyhow were they? Maybe checking it for conformity to utility requirements and installing their meter?

Commissioning has a meaning in industry - maybe it means something entirely different for residential.

[Sunking]

OK - Electrical in the US is more strict but sending an engineer or actually 2 (with 4 year degree) to commission a residential solar setup?

No more than likely a 2-year Associate Technician with adequate training.

What they are looking for is that the customer equipment meets current electrical codes, practices, the POCO requirements, metering is correct-accurate, and most importantly the systems shuts down when power fails.

[Ian S]

The POCO wasn't commissioning anything anyhow were they? Maybe checking it for conformity to utility requirements and installing their meter?

Commissioning has a meaning in industry - maybe it means something entirely different for residential.

Well, when my system was "commissioned", all the utility inspector did was check the breaker panel (and marvel at how ancient it was) and watch while the installer electrician installed the meter for measuring solar production. The bi-directional POCO meter had already been installed the previous day. She placed a warning sticker on the POCO meter box and then another warning sticker on a nearby transformer box. Then she filled out some paperwork and the system was turned on. Oh, there was also some mention of how lucky I was to get her because if it had been a hard ass inspector, they would have found fault with the location of the electrical service so close to water and natural gas incoming.

[ocoee]

On average , unless you have shading issues, the additional cost for a micro inverter has about a 47 year pay back EnPhase vs SMA or similar.

If you want the no money out of pocket thing.. Look at a home improvment loan from someone like Admirals bank. Not pushing them there are just who We use.
In Colorado you can have a 5kw system installed for 25,000. you keep the tax credit, you keep the REC payments every month. You write off the intrest on a home improvement loan. The system cash flows from day 1 because you loan payments are less then your utility bill were, plus you write them off! Typical pay back is 7-11 years We have never sold a lease after showing this option to a client.

I can not speak directly to your incentives but here in Denver area they are not so good and the math still pencils out.

A lease system is an investment ...for who ever owns it, just not for you "opinion"

[bwillng]

Well, when my system was "commissioned", all the utility inspector did was check the breaker panel (and marvel at how ancient it was) and watch while the installer electrician installed the meter for measuring solar production. The bi-directional POCO meter had already been installed the previous day. She placed a warning sticker on the POCO meter box and then another warning sticker on a nearby transformer box. Then she filled out some paperwork and the system was turned on. Oh, there was also some mention of how lucky I was to get her because if it had been a hard ass inspector, they would have found fault with the location of the electrical service so close to water and natural gas incoming.

Here in the UP of Michigan I just across the border from Wisconsin, so we have WE Energies as our power supplier. The engineer run test and recorded the results to make sure the system turns off in less than 2 seconds and that it turns on after power is resumed at least after 5 minutes. If the system turns on in less time the system has failed! My system turned on in 5 min 2 sec

[billvon]

Engineers commissioning a residential solar system? I doubt these guys ever have or ever will design much of anything and I doubt any university degrees are involved.

I agree. (Which is why I put engineer in quotes.)

One should certainly not be scared to ask about the background of someone doing work FOR you.

Also agreed, but the best time to ask is probably not when they are trying to decide whether to sign off on your system.

[bwillng]

there will be some voltage drop but not significant.
If and when you get your Envoy communications with the inverters may be an issue. The Envoy will need to be set and plugged into an outlet right next to the electric panel. If the internet connection is not right there you will need the Enphase ethernet bridge to continue to the router.

Bought the envoy with two communication bridges and it still will not communicate with the house. I get 4 bars in the garage at the envoy and can read output of system and all 16 panels are communicating with the envoy but can not get it to recognize the internet in the house which is 124 feet from the power cable comming in to the house. Any ideas?
The garage which was built first there is a main power panel which has a auxilary 100 amp panel and the solar system is connected to this panel. When we built the house a power cable from the main panel in the garage connects the house which is 124 feet long.

[Coyotefred]

Another 'solution' to TED/Enphase communication conflict

I had real problems with TED and Enphase conflicting with one another too. The most noticeable effect was inconsistent/erratic reporting on the Enphase Envoy (only one panel showing up, one panel showing "0 watts" etc. in Enlighten) The recommended solution (to have a dedicated circuit for your TED 5000 which is then "islanded" from the rest of your grid by using filters) has worked for some, but I have 4 TED MTU/CTs spread out over several buildings (one 330' away from my home/computer) so that was not going to work for me.

And there really wasn't a similarly-priced alternative to TED (Current Cost/Envi has too limited of a communication range and it was uncertain Brultech would work over a 300' distance too).

So what I ended up having to do was create a filtered circuit for the *Enphase.* 'Tough part was that my panels/Enphase M215s are mounted that building 330' from my house. So basically I used inline filters to isolate the branch circuit the panels/M215s were on in that remote building, and then I ran a 300' powerline *from within that filtered branch circuit* back to my house/computer. I then plugged the Envoy into that powerline (I won't use it for anything else) and so far everything is golden...no more conflict between TED and Enphase. 'Kind of a PITA, however, but a solution... I also tried running Cat5E to cover that distance but that didn't work (that's near the limit of a Cat5 run I think), and I didn't want to go down the road of a wireless ethernet bridge, etc., so I just went with the powerline solution... 'Not real elegant but it did work and now Enphase and TED are finally playing nice together

.02 cents

Yes, I ran into the communication problem also. I use the TED system to monitor my electrical use. A quick and timely phone call to Enphase verified my suspicion that the Envoy system and TED system are incompatible and conflict with each other.

[inetdog]

I also tried running Cat5E to cover that distance but that didn't work (that's near the limit of a Cat5 run I think), and I didn't want to go down the road of a wireless ethernet bridge, etc., so I just went with the powerline solution...
.02 cents

Another alternative which *might* work would be to put an Ethernet hub or switch somewhere near the midpoint of the 300' run. If necessary you could run power to it over the unused pairs in the same CAT5 cable.

And for the network adepts, you can connect each unit to a common Ethernet network using switches which divide the system up into separate VLANs which do not interact with each other.... (Sorry, getting carried away with geek enthusiasm.)

[rick1]

When I was designing my solar grid tied system, I was attracted to the Micro Inverters. But I hit a roadblock when I did the voltage drop calculations because my array was situated 260 feet from the house. This is a very critical calculation since Micro Inverters output at 240 volts AC. As most of you know, lower voltage creates higher voltage losses over long distances and thus large power losses. But the real problem is if the AC voltage drop is out of range for the Micro Inverter, it will shut down.

I was able to over come the distance (ie voltage drop) problem by designing a higher voltage DC home run to a single inverter mounted on the house without using huge copper lines.

This factor alone precluded me from using Micro Inverters. I seldom, if ever, see this discussed in the pros and cons of Micro Inverter discussions.

My 10.8 kw system is 300 ft. from house. used micro inversters. used 1/0 copper from array to house main breaker panel. works great. https://enlighten.enphaseenergy.com/...tems/GWAq70281

[DanS26]

My 10.8 kw system is 300 ft. from house. used micro inversters. used 1/0 copper from array to house main breaker panel. works great. https://enlighten.enphaseenergy.com/...tems/GWAq70281

Rick,

Just a couple of questions. Your array pic shows 48 panels. Do you just have 2 in reserve, since Enphase site says only 46 are actively producing?

My rough calc says you spent over $2k to run 300 ft of 1/0 copper wire. Along with 46 or 48 Enphase inverters and 48 235 watt panels. Just wondering if you are seeing a positive return and if so what is your payback? Did you pay to have it installed or was it DIY? Do you have net billing or net metering?

I have 36 235 watt Kyocera panels with a Fronius 7.5 inverter. Very pleased with the system as commissioned on 11/17/11. Have produced over 5Mw so far and if PVWatts is correct I should see a payback in about 8 years. So far PVWatts projection have been right on.

My wire savings alone was almost enough to pay for my string inverter. I liked the Enphase system but money was the final winner.

[inetdog]

My 10.8 kw system is 300 ft. from house. used micro inversters. used 1/0 copper from array to house main breaker panel. works great. https://enlighten.enphaseenergy.com/...tems/GWAq70281

For long runs of either AC or DC, as long as you use the proper terminations and methods, you can use a larger gauge Aluminum wire at about 1/3 the total cost for wire.