[RE-wrenches] Minimum Lux needed

[Kelly Larson]

Hi Benn,

It's from my own experience.  I teach classes and find that is around the minimum irradiance for full voltage.  Of course it is a little different for different modules, and levels of diffuse versus direct sunlight.  But the difference in time between when a spot will see 100 and 300W per square meter on modules on a clear morning is a few minutes.  And would their detector be pointed at the sun already?  What is considered "usable electricity"?  If the tracker is connected to a gridtied inverter, it would be inverter wakeup that would determine all this, I would think.

It sounds like you could use some scientific research.  Likely NREL has research on this, but they would probably call it irradiance, light intensity, or something like that, which could be converted to LUX.

Blessings,
Kelly

On Sep 5, 2013, at 9:28 AM, Benn At DayStarSolar wrote:

> Thank you Kelly. 
> Not that I don't believe you, but can you provide any data to back this up?
> I should have asked for that upfront. 
> 
> benn
> Sent from a 'smart' phone, with touch screen keys. Please excuse shortcuts and typos. 
> 
> On 2013-09-05, at 10:24 AM, Kelly Larson <solarwrench at asis.com> wrote:
> 
>> Hi Benn,
>> 
>> It's around 200W per square meter.
>> 
>> Blessings,
>> Kelly
>> 
>> Kelly Larson
>> Electrical Engineer
>> NABCEP Certified Solar PV Installation Professional
>> ISPQ Master Trainer
>> CA Electrical Contractor# 868189
>> SolarKelly.com
>> 
>> On Sep 5, 2013, at 9:06 AM, Benn At DayStarSolar wrote:
>> 
>>> Wrenches,
>>> I was asked... What is the minimum Lux level required to make usable electricity with a commonly installed monocrystaline PV module. 
>>> 
>>> The question is for the purpose of designing a tracker that will not operate until a particular threshold is reached. 
>>> Thanks,
>>> benn
>>> Sent from a 'smart' phone, with touch screen keys. Please excuse shortcuts and typos. 
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