Micro-Inverter vs Standard

[gasstingy]

Trevor,

Most of the info I have from the tilt angle is taken from a number of different articles I've read in Home Power Magazine. That said, if I were roof mounting my panels, I personally would use 44 degrees, or rather, as close to 44 degrees tilt angle as I could get.

Mine are all ground mounted on adjustable racks for several reasons:
First and most important, my wife was okay with me buying all the solar equipment I wanted as long as I did not touch the roof of our house.
Second, our roof doesn't face true south.
Third, I wanted to be able to clean them without danger of falling off my roof as the drop would be about 14'.
Finally, we have plenty of room in the back yard so the amount of room they take up isn't an issue. The small array's footprint is about 7' square. Add a foot and a half gap to the bigger array. The bigger array is about 42' long by 12' wide.

[pinballlooking]

Did you decide on a system?
One thing I like about micro inverters is one fails you only loose one panel not the whole system.
It is very easy to know if one panel is bad or going bad. You get good level of data provided at a panel level.

[pinballlooking]

Originally Posted by GaryGary

Hi,
I have a 2.2 KW Enphase inverter system -- going on 3 years old.

Have not had any problems or failures.

At the time I did mine, the microinverters cost about the same as a single string inverter, and I liked the flexibility to add panels later, the separate MPPT for each panel, and the simple installation.

I've been happy with them, and have grown to like the web page they setup for you to get reports on the system. Their monitoring system (which is now free), also lets you know when any inverter is having problems -- kind of strange when you get an email from your inverter I've received a handful of notifications that something was wrong with the advice to just give it an hour and see if it clears itself -- it always has.

It gives you a separate power report for each panel/inverter, and I think this is useful -- for example, if you think power output for the system is down, you can look at what each panel is doing, and see the one that is causing the problem.

I like building stuff, but I'm not so good about looking after it after its built and doing the routine checks to make sure everything is still working, so the automated reporting including faults is nice for me.

The install is easy -- I did mine including permits and all -- the pictures here give an idea of what's involved: There are some more DIY installs here: Tie
In particular, take a look at "Doug's New 4.6 KW..." system.

While the micro-inverters make for an easy install, I don't think the string inverter install would be much harder.

I guess some places it can be a pain for permits and inspections and meeting utility rules, but here in MT its cheap, simple and fast. I was up and net metering a week after the system was finished.

Solar Today did a nationwide survey a few months ago on what people were paying for professionally installed systems. The US average was over $6 per watt (may have dropped a bit since). Places are offering pretty complete kits for less than $2 a watt. There will be stuff to add to the $2 per watt, but not a while lot in terms of $'s per watt, so, it seems like there is still quite a bit of money to be saved for a DIY installation?


Gary

Gary
Thanks for posting your system it really helped me along the way. It also shows that micro inverters are a little simpler for a home owner to do a self-install.

[where2]

Originally Posted by pinballlooking

...It also shows that micro inverters are a little simpler for a home owner to do a self-install.

They are very simple. I've self-installing a 4400W grid-tie system. I was just up on my roof this evening torquing down the last few M215's, and routing my #6 ground wire through all the inverter case screws and rail Weebs. I've got one pocket full of red trunk cable shipping caps, and an enphase disconnect tool in my other pocket.

In Florida, my biggest challenge in permitting and home-owner self-installing a roof mounted PV array was the structural engineering necessary to keep the array on the roof in a 3 second gust of 170mph. 4400W is just the beginning for me... There will be more.

[pinballlooking]

Originally Posted by where2

They are very simple. I've self-installing a 4400W grid-tie system. I was just up on my roof this evening torquing down the last few M215's, and routing my #6 ground wire through all the inverter case screws and rail Weebs. I've got one pocket full of red trunk cable shipping caps, and an enphase disconnect tool in my other pocket.

In Florida, my biggest challenge in permitting and home-owner self-installing a roof mounted PV array was the structural engineering necessary to keep the array on the roof in a 3 second gust of 170mph. 4400W is just the beginning for me... There will be more.

That is great I would love to see pictures. I am glad we do not have structural engineering issues here.

[NeilBlanchard]

Micro-inverters are better in shadowing situations - you lose the output from individual panels that are too shaded, but the rest keep on going. With one main inverter, with too much shadow the whole array stops any output. I believe micro-inverters are less lossy, since the longer wires are AC?

[Daox]

Originally Posted by NeilBlanchard

I believe micro-inverters are less lossy, since the longer wires are AC?

In general I think that is true. If you're running high enough voltage DC power it might not be, but that can't be real common running that high of DC power.

[Mikesolar]

Although the voltage is all over the place, most string inverters have inputs between 250Vdc and 550Vdc bit it is really up the the inverter architecture as to how may series panels they can handle. The cost of the micro inverters is more and there is more custom equipment with the trunk cabling but it may be easier for the layman to install. It is all the same to me.

[pinballlooking]

Originally Posted by Mikesolar

Although the voltage is all over the place, most string inverters have inputs between 250Vdc and 550Vdc bit it is really up the the inverter architecture as to how may series panels they can handle. The cost of the micro inverters is more and there is more custom equipment with the trunk cabling but it may be easier for the layman to install. It is all the same to me.

If you have a string inverter how do you tell if you have one panel underperforming?
I recent had one panel underperforming I clearly showed up in the web monitoring. I went out to the array and this huge feather was on one panel I removed it and I was back in business. only one day of reduced power on one panel very cool.

[Trevor]

I decided to go with the micro-inverter (Enphase). I am installing qty 40 ET 250w panels on a new garage. Hopefully it will stop raining here in Vermont long enough for me to install them. Rails are up, but I am not getting on a metal roof with a 8x12 roof until it is dry. My costs are right around where I budgeted which was $22k, even though I may need to hire someone to assist with carrying them up the roof. I mounted the inverters for the top row this weekend in hopes that I could get someone to help me this week to install the first 10 panels.