I found the latest module rightsizing paper by Enphase pretty
interesting. It does stand to reason that there are a lot of hours in the
day where the inverter is producing less than rated power, so increasing
the module size makes sense. Obviously there is an optimum point in every
system where
Carl;
The Iotas we are using have an external jumper that you insert that allows
it to get to EQ voltage.
DAN
On Sun, Jan 27, 2013 at 7:31 PM, Carl Hansen solar...@cybermesa.com wrote:
Dan,
You may be do this as well, but I frequently deal with homeowners with
inexpensive generators,
When looking at the various systems we have installed with different
module/inverter combinations itÂ’s hard to make a perfect performance
comparison as tilt, orientation, module, and degree of transient shade vary
considerably. Additionally many string inverters we have out there do not
have web
In a grid tied system the question becomes how much clipping and how often.
Intuitively we all know little clipping is probably ok but a lot of clipping is
a bad thing. How much is ok is the question.
Ultimately we should all be concerned with economics (LCOE / ROI). The
clipping experienced
Hi Dan,
The Iota jumper only raises voltage by 0.6 volts above the default setting. You
will need to insert the jumper AND adjust the voltage POT (now internal) to
reach the EQ range.
For off grid systems, I usually turn up the Iota voltage POT fully since
generator run time is rarely
For that particular site, no. As far as I know a database is not being
maintained. That is, what you see at any given moment is what you get. But
I will check. Once we get into Spring and Summer with higher sun angles, I
will be able to see what kind of clipping would have taken place since I
Jason:
Be careful of drawing false comparisons. There is no free lunch.
Beyond the energy yield issues there are some reliability issues.
You should also consider that running an inverter flat out all the time will
shorten it's life (due to the Arrhenius effect).
Another thing to think about when the system is oversized for the
inverter being used (or charge controller)
and it clips all the time (I call it current limiting), is that the
input voltage will rise to reduce the output
power (to keep it limited) which will usually make the inverter or
Hi John,
It's important to clarify that the clipped power does not turn into heat
within the microinverter. The microinverter only draws enough current to
achieve it's max output rating, and the remaining current is left in the
module, so to speak. So, the heat generated at peak times is the
The initial issue was concerned with waste power, but that presumes all
power is priced evenly. Take a familiar situation, you specify and sell the
system based on a number of 240W modules. Let's presume time passes and
when you go to buy out the job, you find there is a deal on 260W modules
which
Hi Marco
Here is our experience with that knowing that we are at 6000 to 8000 foot
elevations.
We have seen significant differences in module delta temperature to ambient
for ground mounts vs roof mounts and that is where we become concerned about
oversizing the module or array. For a
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