Enphase Mico Inverter

[doccyber]

I am looking at 2 bids for my solar system, one company insists that I should get micro inverters for my system for improved performance and also it would make shade a less of an issue. The other company on the other hand says that the technology is not approved for residential installation and my power utility will not allow it. Is this true? Incidentally the lease program is also 3 times more expensive for the company that is pushing the micro inveterter. I have done research on this and it seems that micro inverters have been around for a while.

BTW I am a totally new to this and any responses would be greatly appreciated. I am trying to decide soon.

Thanks.

[russ]

Hi and welcome to Solar Panel Talk!

Microinverters are installed in many locations - long term the jury is still out but they seem to be working fine.

The microinverter is best if there are any shading problems. They offer little advantage if there is no shade to contend with.

A company that says 'the technology is not approved for residential installation and my power utility will not allow it' is either misinformed or outright lying it would seem. Best if you give your utility a call. Don't get into a long winded discussion but ask the simple question, 'Can microinverters (Enphase or what ever brand is being proposed) be used in a grid connect system?'

You can also contact the microinverter supplier for input.

Three times more expensive does not mean much unless we know amounts.

Russ

[doccyber]

Thanks Russ for a quick reply

Company #1 20 year lease for 18600 Dollars Annual Production of 13000 Kwh
Company # 2 20 year lease for 7100 Dollars Annual Production of 10800 Kwh

They both cover all maintenance, full monitoring and warranty for 20 years plus removal.

I use about 12000 Kwh per year.

Company #1 local and #2 a large national company.

[russ]

The bigger and nationwide company probably has a better chance of being around for a few years

The one saying the microinverters can not be used is highly suspect.

20 years of free monitoring from a defunct company isn't worth a whole lot.

You lose far more opportunity with the much larger up front payment with the local party.

[Naptown]

Looking at your numbers there
The more expensive system is probably a larger system in DC watts judging by the production numbers. Micro's will produce more but not that much more. 5-7% is more like it.
There is no reason that a utility or AHJ would not allow micro inverters they are approved and UL listed. They do however cost more. The less expensive company is most likely solar city or sungevity These leasing companies do not allow micro's not the utility or local inspectors. For 1603 grants which they are probably still working under I believe the monitoring on the micro's will not meet the Federal reporting requirements.
The second is either a suncap or Sunpower lease.
These are run through local dealers and the leasing company just buys the system from them. They are allowed to charge whatever they like. Both have microinverter options.

Now the crux of the situation. are there any shading issues on the roof they are proposing to mount this on. I would use this as a determination of which way to go either micro or string inverter.

Lastly shop around a bit more you may be able to get a straight purchase at as good or better a deal than either.

And in the interest of full disclosure I am a solar contractor.

[doccyber]

Thanks very informative.

How do I know what are some good local companies? I got the names from 2 co workers that had looked into this. Is there a data base to look up?

[Naptown]

Where are you located

[doccyber]

Los Angeles, CA

Thanks.

[Naptown]

Los Angeles, CA

Thanks.

I'm pretty sure the state website has some contractor names
try www.gosolarcalifornia.org

[DanS26]

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.

[Naptown]

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. 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.

I do the same thing. I run a high voltage DC line to a String inverter at the house. I have done several that were discussed here (but mostly about the ECG) The other issue with the long runs is communication issues with the Envoy. The error messages will drive you crazy. Last one I installed the original vendor was proposing 25KW in a field array 600' from the meter and another 100' to the panels. there would be no communication of the inverters to the envoy at that distance and the voltage drop was insane. (read very expensive wiring)

[DanS26]

I do the same thing. I run a high voltage DC line to a String inverter at the house. I have done several that were discussed here (but mostly about the ECG) The other issue with the long runs is communication issues with the Envoy. The error messages will drive you crazy. Last one I installed the original vendor was proposing 25KW in a field array 600' from the meter and another 100' to the panels. there would be no communication of the inverters to the envoy at that distance and the voltage drop was insane. (read very expensive wiring)

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.

[solarpowered]

Micro inverters have many down sides.

CONS:
They sit out on hot roofs, so harvest efficiency isn't really what the big claims are, life expectancy aren't what the claims are
Harvest efficiency is limited to roughly 95.5% between solar bridge and enphase micro inverters
Voltage drop on AC side after 100' sucks
PRO's:
If one panel is shaded it doesn't effect an entire string, as string inverters do
Micro inverter systems require less parts concerning disconnects and combiners, so there are some cost savings.
Although the micro inverters don't live there life expectancy, companies such as solar bridge do warranty for the life of panels

[russ]

Micro inverters have many down sides.

CONS:
They sit out on hot roofs, so harvest efficiency isn't really what the big claims are, life expectancy aren't what the claims are
(? WTF are you talking about - neither of your points are any more than an uneducated guess)

Harvest efficiency is limited to roughly 95.5% between solar bridge and enphase micro inverters
(Rich can reply - this is his baby)

Voltage drop on AC side after 100' sucks
(another wild statement)

PRO's:
If one panel is shaded it doesn't effect an entire string, as string inverters do
(correct)
Micro inverter systems require less parts concerning disconnects and combiners, so there are some cost savings.
Although the micro inverters don't live there life expectancy, companies such as solar bridge do warranty for the life of panels
(You have proof of the life of the micro inverters or just talking?)

Russ

[Naptown]

Micro inverters have many down sides.

CONS:
They sit out on hot roofs, so harvest efficiency isn't really what the big claims are, life expectancy aren't what the claims are

Enphase warrants their m215 for 25 years They are designed for the ambient temperatures they will encounter

Harvest efficiency is limited to roughly 95.5% between solar bridge and enphase micro inverters

Try getting a derate that low with a string inverter and they are not more than 96% efficient.

Voltage drop on AC side after 100' sucks

That is a function of system design and on extremely long runs they are not cost effective

PRO's:
If one panel is shaded it doesn't effect an entire string, as string inverters do

Got one right

Micro inverter systems require less parts concerning disconnects and combiners, so there are some cost savings.

Not really the inverters themselves cost more than an equal size string inverter on a similar system.

Although the micro inverters don't live there life expectancy, companies such as solar bridge do warranty for the life of panels

As said above so does Enphase (at least on the 215)

My comments in red