Re: Lowes selling solar collectors

On Sep 8, 9:28 am, "trad...@xxxxxxxxxxxxx" <trad...@xxxxxxxxxxxxx>
wrote:
On Sep 8, 2:36 am, gfretw...@xxxxxxx wrote:









On Wed, 07 Sep 2011 19:27:08 -0500, Jim Yanik <jya...@xxxxxxxxx>
wrote:

green...@xxxxxxxxxx wrote in
news:u9cf67p56c4ls6v7bp92bm2opbdn868alt@xxxxxxx:

On Wed, 07 Sep 2011 11:13:35 -0500, Jim Yanik <jya...@xxxxxxxxx>
wrote:

Hell Toupee <w...@xxxxxxxxxx> wrote in
news:j47ocb$6n5$1@xxxxxxxxxxxxxxxxx:

On 9/6/2011 6:30 PM, JimT wrote:
On 9/6/2011 5:55 PM, gfretw...@xxxxxxx wrote:
Akeena Solar is selling a plug in grid tie solar collector aimed
at do it yourselfers.
Just plug them in any 120f receptacle and aim them at the sun.

Cite?

http://www.popularmechanics.com/science/energy/solar-wind/4317039

"...the firm Andalay Solar debuted its new AC panel, which
eliminates the need for elaborate DC wiring and large, system-wide
power inverters by building micro-inverters into each individual
panel. For buyers willing to dip a toe in solar, the panels can be
installed one at a time. For installers, the built-in racking,
wiring and grounding allows a full 3-kilowatt system of about 20
panels to be installed by a two-man crew in less than a day..."

for a 3KW array,you better have some sort of transfer panel.
just as you would for any whole-house generator.
it could save someone's life.someone could throw the breaker and think
the wiring was safe to work on,while the solar array was still
supplying power and keeping the system "live".

also,will all those separate inverters stay synchronized?
Yes, they will.  They monitor the line and sync with it.  A small
microprocessor that only adds a few dollars of cost takes care of all
that complex computations required to do so.  I also believe they will
automatically shut down if regular AC power is lost.

what's the point of having solar panels if they shut down when you lose
mains power and REALLY need them?
3 KW would easily keep your fridge going and your food unspoiled.
(and your beer cold!)
3 KW would probably power the entire home,excluding heating or airco.

I would like to know how they do that, though.  If you have ten of
them plugged in, how do they tell the difference between commercial AC
power and each other?

Perhaps they note the loss of the 60 HZ mains freq;with no sync signal,they
shut down. If the panels tried to sync to each other,they would quickly
drift to some out-of-spec limit. (lacking any reference)
Hopefully,a narrow limit,as too far off 60 HZ can damage some appliances.

Plug in collectors have been around for a year or two. They simply
shut down when the grid stops. I agree it is not useful in a power
failure but that is true of any grid tie system.

I can see the obvious need for any solar array to disconnect
from the grid when the grid power goes down.  The more
interesting question is why no one has a system that will
allow the home to still be powered by solar while
disconnected from the grid.   There are obvious issues
with that too, like the house experiencing brownout when
the sun goes behind a cloud.  But you would think with
some smart's in the controller it could allow the house
to be powered, no?   Say for example, the controller
detects 50% of max power from the array for 30 mins
continuous, ie it's a reasonably sunny day, so it
turns on power to the home, but not the grid.  If it
can't meet the load because it then gets cloudy, it
could turn off, then repeat process.   I guess the
issue is how well that would work, for how many
parts of the country, etc vs the added complexity
and the annoyance of having power come and go.


These things are U/L listed so I am not sure exactly how the AHJ can
stop anyone from using them. U/L says they have been tested and they
are safe. What would you cite?- Hide quoted text -

- Show quoted text -

In a practical solar emergency back up system there will be a battery
bank. The batteries add markedly to system costs and require periodic
replacement. A battery charging controller can use a grid tie
inverter as a diversion load for the system. When the batteries are
charged the output of the solar array is diverted to the grid tie
inverter. When the batteries need recharging they get the solar array
power they need via the charge controller with any excess power
diverted to the grid tie inverter. An automatic or manual transfer
switch transfers the emergency loads to a separate regular inverter
that runs off of the batteries when utility power is absent. The grid
tie inverter senses the emergency inverter output as non utility and
does not turn on unless the emergency power inverter is of the true
sine wave output type in which case the grid tie inverter will
synchronize with the emergency inverter and share the load. That
would have the effect of increasing the loads the emergency system
could carry up to the limit of the solar and or battery capacity
available.

Some generators can deceive a grid tie inverter. The larger the
generator and the better its power quality the more likely that is.
The good news is that there is no danger caused by that as long as a
proper transfer switch is used on the emergency inverter and generator
system. The grid tie inverter will only reduce the load on the
generator and if you use the battery charging and emergency power
inverter system then the grid tie inverter would only get the extra
current that wasn't needed by the batteries. The switching and
sharing of the solar arrays output is all handled by the charge
controller or an add on diversion controller. If an automatic
starting generator is available the emergency inverter will signal it
to start if the load exceeds the capacity of the emergency inverter or
if the battery voltage drops to it's minimum safe level.
--
Tom Horne
.

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