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How many panels ? ( to run 230 volt sprinkler pump 30 minutes a day?) - Page 9

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Posted by bealiba on July 15, 2008, 11:12 pm




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You brought up PTC in hopes of muddying the water a bit more in your
quest to sound knowledgeable.

Posted by Ron Rosenfeld on July 14, 2008, 8:48 pm
On Sun, 13 Jul 2008 16:02:23 -0700 (PDT), bealiba@gmail.com wrote:

It is truly sad that reality does not match George's fantasy.

Posted by bealiba on July 15, 2008, 7:46 am
We're still waiting on your all inclusive spread sheet that allows for
all the solar equipment in the world and complete pricing for same.

We are also waiting for yor caluclation for the numbers you proposed
for this post;

From Tweedledee -

Let's get back to this challenge of yours, as to whether your
specifications will run the OP's 2500watt pump 1/2 hour per day, every

You give incomplete specifications, so it's a tough to run a
But perhaps, if you can fill in a few details, or agree with some of
assumptions, we can proceed with a simulation:

With regard to your selected module:

Does this mean it has an STC nameplate power rating of 14*2.94 = 41.16
watts?  Or is the STC nameplate power rating something else?

I will round this up to 11.

Do you want to consider the effect of temperature on the module?

If you do, then we need to use some assumptions about the temperature
coefficient, NOCT and MPPT efficiency at std. test conditions.

I would assume
        Temperature coefficient of power = -0.5%/C
        NOCT                                45.2C
        MPPT Efficiency at std test cond     13%

but we can use different values if you like, or ignore temperature

With regard to the battery, you have supplied this information:

The real world battery I could find (in my database) closest to these

Trojan T105
        Maximum allowable depth of discharge = 70%
        Capacity at 100 hr rate              = 240
        Efficiency                              85%

So I would use two of these in series to provide a 12V battery bank.

Well, come on you have the formula, these are the numbers you feel
should be used, show us the calculation.

Posted by Ron Rosenfeld on July 15, 2008, 8:02 pm
 On Tue, 15 Jul 2008 00:46:05 -0700 (PDT), bealiba@gmail.com wrote:

I'm sure *YOU* would require something like that, so you can blame any of
your misguided recommendations on whoever devised the database.  But a real
solar power consultant would not.

And I'm waiting to see if you agree with any of them.  Clearly, you cannot
recommend an efficient real-world system.

I was trying to help you formulate a real world system to run through the
simulation.  Clearly, that is beyond your ability.  Sad.  Especially for
one who claims to be knowledgeable in this field.

In another post, GG writes about me: "He has learned more about solar
in the last two weeks than he ever learned in the last 10 years."

What I've learned in the last two weeks is that GG is even less competent,
and less able to learn, than I had originally concluded.  That shouldn't be
a surprise, I know.  But I did have hopes.

He can't specify either a real world panel or a real world battery for his
Kilauea water pump system.  He can only come up with unrealistic
specifications, and, when real world specifications are proposed to him, he
can neither accept them, nor propose different ones.

And then, to compound his errors, he writes:

If his 45C is an ambient temperature, he's someplace far from Kilauea, HI
where the highest annual temp is around 33C, and the average annual temp is
about 29C.

If he's trying to compare what happens at STC (which is at 25C), when we
change the conditions so that the operating cell temperature (OCT) is the
NOCT, then he doesn't know what NOCT is or how to calculate it.

Hint for GG:  The OCT at STC will be higher than the NOCT.

Posted by Solar Flare on July 15, 2008, 9:20 pm
 He seems smart enough to invoke many responses from the so-called
"brainchilds" here. Where does that put you?

Maybe a little maturity would help you out?

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