On Thu, 20 Aug 2015 15:14:46 -0400, "Tom" wrote:

Can you comment on the fact that these Enphase converters need 240ac volts
(grid connection) to run? This means that if ever the power supplier
locally ever shuts down for more than a long period of time that these
Enphase units become useless. Around my neck of the woods we are getting
more and more power outages lasting longer and longer. These inverters
require being connected to the grid to function.

Yep, been there. Almost everyone that has a grid tied solar system
wants to know what it will take to make it run when the power is down.
Home Power Magazine had a nice article on the topic in the current
issue (168):
http://www.homepower.com/articles/solar-electricity/design-installation/adding-battery-backup-your-pv-system-ac-coupling
The magic buzzword for Googling is "AC-Coupled Battery Backup PV
System" (or something like that). Note that there are both DC and AC
coupled approaches to the problem, each with their own advantages and
problems.

Note that Elon Musk wants to do much the same thing but not to backup
your solar PV system. He wants to store excess power in a battery
bank, and return it during times of peak loads to save money using
time of use billing.
http://www.wired.com/2015/05/teslas-batteries-will-power-home/

I understand the safety requirement and it needing to do this to be
certified but it really limits the home owner (or cottage owner in my case).

Yep. All of the stuff in the article is probably approved, but I
would be careful and check, especially with made in China hardware
purchased on eBay.

Have you ever worked on a system that was more practical?

More practical than what? I've done nothing with AC coupled backup
systems for grid tied PV systems, mostly because none of my customers
will tolerate the cost. It's often cheaper to just buy a big
generator and let it sit around until it's needed. Diesel seems to be
the favorite.

That qualified for
the grid program but was useful when detached from the grid? Seems to me if
ever the power company decides to cancel the program you may be stuck with
40 inverters that are useless and are 200 dollars each.

You're mixing up a bunch of programs. First, your power company is
unlikely to pull the plug except for non-payment. It might decide to
cancel subsidies or refuse to offer net metering payments, as happens
in many states. In California, if the power is lost for extended
periods, there is some fixed amount that the power companies are
required to refund the customer on their next bill. That too might be
terminated. At this time, power generation and distribution is mostly
a "best effort" exercise, with little in the way of guarantees
covering extended outages.

If you're dependent on a sole source of power, such as utility *OR*
PV, then you'll have the same problem with outages. My best
suggestions is to have more than one source of power. Utility and PV
are the most common. There's also wind and micro-hydro generation.
Batteries don't generate electricity so they're not considered an
alternative power source. Once you have your power source in place,
then you can think about storage options.

Any comments are thankful,

If you wanted to be off the grid, then kindly plan your system for off
grid use. That mostly eliminates grid tied systems and always
requires batteries or other forms of energy storage (maybe flywheel).
Instead of micro-inverters, you're back to the big charger/controller
boxes, and banks of batteries.

Batteries are always a problem. They require constant care. They
tend to die rather quickly. They're expensive. They're big, ugly,
and dangerous. They're far too easy to kill. Before dealing with
batteries, make sure you know what you're getting into.

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558