Posted by *Peter Mounsey* on June 3, 2004, 10:12 pm

I've just fitted 4 Evergreen EC55 panels to my 24v system. Panels wired two

series strings in parallel. So, with 220 watts into 24 volts I should be

seeing 9.17 Amps - right?

What I am seeing is a maximum of 5 Amps in very intense Spanish sun, panels

correctly aligned and all panels producing the same power.

Am I missing something here or are rated outputs fantasy?

TIA, Peter.

Posted by *Solar Guppy* on June 3, 2004, 10:34 pm

http://www.evergreensolar.com/egsolar1/pdf/EC-50_v2.7e.pdf

Shows the EC-55 as 3.33 amps when at VMP (maximum power point)

Since you have two in series , that doubles the voltage but the current

remains the same

Since you have two strings in parallel , that would double the current to

6.66 amps

The EC-55 vmp is 16.5 volts , so two in series is 33 volts , and in your

configuration (best case) would be 33 volts at 6.66 amps which is 218 watts

So NO , your not going to see 9.17 amps , look at the data sheet

5 amps seems reasonable ... you'll need a mppt charge controller though to

see the 6.66 amps and this and it will only be a solar noon on a perfect

day

It's has nothing to do with evergreen panels , all Silicon panels are this

way

*> I've just fitted 4 Evergreen EC55 panels to my 24v system. Panels wired*

two

*> series strings in parallel. So, with 220 watts into 24 volts I should be*

*> seeing 9.17 Amps - right?*

*> What I am seeing is a maximum of 5 Amps in very intense Spanish sun,*

panels

*> correctly aligned and all panels producing the same power.*

*> Am I missing something here or are rated outputs fantasy?*

*> TIA, Peter.*

Posted by *Duane C. Johnson* on June 4, 2004, 12:54 am

Hi All;

Solar Guppy wrote:

*> http://www.evergreensolar.com/egsolar1/pdf/EC-50_v2.7e.pdf *

*> Shows the EC-55 as 3.33 amps when at VMP (maximum power point)*

*> Since you have two in series , that doubles the voltage but*

*> the current remains the same*

*> Since you have two strings in parallel , that would double*

*> the current to 6.66 amps*

*> The EC-55 vmp is 16.5 volts , so two in series is 33 volts,*

*> and in your configuration (best case) would be 33 volts at*

*> 6.66 amps which is 218 watts*

*> So NO , your not going to see 9.17 amps , look at the data*

*> sheet*

*> 5 amps seems reasonable ... you'll need a mppt charge*

*> controller though to see the 6.66 amps and this and it*

*> will only be a solar noon on a perfect day*

It's probably quite warm in Spain now.

This will have the effect of reducing the panel efficiency.

So the resultant current will be even less than expected.

*> It's has nothing to do with evergreen panels , all Silicon*

*> panels are this way*

*> > I've just fitted 4 Evergreen EC55 panels to my 24v system.*

*> > Panels wired two series strings in parallel. So, with 220*

*> > watts into 24 volts I should be seeing 9.17 Amps - right?*

*> > What I am seeing is a maximum of 5 Amps in very intense*

*> > Spanish sun, panels correctly aligned and all panels*

*> > producing the same power.*

*> > Am I missing something here or are rated outputs fantasy?*

*> > TIA, Peter.*

Duane

--

Home of the $5 Solar Tracker Receiver

http://www.redrok.com/electron.htm#led3X [*]

Powered by \ \ \ //|

Thermonuclear Solar Energy from the Sun / |

Energy (the SUN) \ \ \ / / |

Red Rock Energy \ \ / / |

Duane C. Johnson Designer \ \ / \ / |

1825 Florence St Heliostat,Control,& Mounts |

White Bear Lake, Minnesota === \ / \ |

USA 55110-3364 === \ |

(651)426-4766 use Courier New Font \ |

redrok@redrok.com (my email: address) \ |

http://www.redrok.com (Web site) ===

Posted by *Solar Guppy* on June 4, 2004, 2:52 am

Duane,

Si panels have a positive coefficient in regards to temperature ... So hot

panels put out more current , its the voltage that drops

From the same spec

http://www.evergreensolar.com/egsolar1/pdf/EC-50_v2.7e.pdf

Voc decreases 0.41% per C while current increases 0.088% per C , this is in

a rising temperature reference context

*> Hi All;*

*> Solar Guppy wrote:*

*> > http://www.evergreensolar.com/egsolar1/pdf/EC-50_v2.7e.pdf *

*> > Shows the EC-55 as 3.33 amps when at VMP (maximum power point)*

*> > Since you have two in series , that doubles the voltage but*

*> > the current remains the same*

*> > Since you have two strings in parallel , that would double*

*> > the current to 6.66 amps*

*> > The EC-55 vmp is 16.5 volts , so two in series is 33 volts,*

*> > and in your configuration (best case) would be 33 volts at*

*> > 6.66 amps which is 218 watts*

*> > So NO , your not going to see 9.17 amps , look at the data*

*> > sheet*

*> > 5 amps seems reasonable ... you'll need a mppt charge*

*> > controller though to see the 6.66 amps and this and it*

*> > will only be a solar noon on a perfect day*

*> It's probably quite warm in Spain now.*

*> This will have the effect of reducing the panel efficiency.*

*> So the resultant current will be even less than expected.*

*> > It's has nothing to do with evergreen panels , all Silicon*

*> > panels are this way*

*> > > I've just fitted 4 Evergreen EC55 panels to my 24v system.*

*> > > Panels wired two series strings in parallel. So, with 220*

*> > > watts into 24 volts I should be seeing 9.17 Amps - right?*

*> > > What I am seeing is a maximum of 5 Amps in very intense*

*> > > Spanish sun, panels correctly aligned and all panels*

*> > > producing the same power.*

*> > > Am I missing something here or are rated outputs fantasy?*

*> > > TIA, Peter.*

*> Duane*

*> -- *

*> Home of the $5 Solar Tracker Receiver*

*> http://www.redrok.com/electron.htm#led3X [*]*

*> Powered by \ \ \ //|*

*> Thermonuclear Solar Energy from the Sun / |*

*> Energy (the SUN) \ \ \ / / |*

*> Red Rock Energy \ \ / / |*

*> Duane C. Johnson Designer \ \ / \ / |*

*> 1825 Florence St Heliostat,Control,& Mounts |*

*> White Bear Lake, Minnesota === \ / \ |*

*> USA 55110-3364 === \ |*

*> (651)426-4766 use Courier New Font \ |*

*> redrok@redrok.com (my email: address) \ |*

*> http://www.redrok.com (Web site) ==*

Posted by *Duane C. Johnson* on June 4, 2004, 4:22 am

Hi Solar;

Solar Guppy wrote:

*> Si panels have a positive coefficient in regards to*

*> temperature ... So hot panels put out more current,*

*> its the voltage that drops*

*> From the same spec*

*> http://www.evergreensolar.com/egsolar1/pdf/EC-50_v2.7e.pdf *

*> Voc decreases 0.41% per C while*

*> current increases 0.088% per C,*

*> this is in a rising temperature reference context*

Thanks. I had thought they both decreased but I

guess I was wrong.

Although the current increase is so small maybe

the rule of thumb would be closer to generally

calling it even.

*> > Solar Guppy wrote:*

*> > > http://www.evergreensolar.com/egsolar1/pdf/EC-50_v2.7e.pdf *

*> > > Shows the EC-55 as 3.33 amps when at VMP (maximum power point)*

*> > > Since you have two in series , that doubles the voltage but*

*> > > the current remains the same*

*> > > Since you have two strings in parallel , that would double*

*> > > the current to 6.66 amps*

*> > > The EC-55 vmp is 16.5 volts , so two in series is 33 volts,*

*> > > and in your configuration (best case) would be 33 volts at*

*> > > 6.66 amps which is 218 watts*

*> > > So NO , your not going to see 9.17 amps , look at the data*

*> > > sheet*

*> > > 5 amps seems reasonable ... you'll need a mppt charge*

*> > > controller though to see the 6.66 amps and this and it*

*> > > will only be a solar noon on a perfect day*

*> > It's probably quite warm in Spain now.*

*> > This will have the effect of reducing the panel efficiency.*

*> > So the resultant current will be even less than expected.*

*> > > It's has nothing to do with evergreen panels , all Silicon*

*> > > panels are this way*

*> > > > I've just fitted 4 Evergreen EC55 panels to my 24v system.*

*> > > > Panels wired two series strings in parallel. So, with 220*

*> > > > watts into 24 volts I should be seeing 9.17 Amps - right?*

*> > > > What I am seeing is a maximum of 5 Amps in very intense*

*> > > > Spanish sun, panels correctly aligned and all panels*

*> > > > producing the same power.*

*> > > > Am I missing something here or are rated outputs fantasy?*

*> > > > TIA, Peter.*

*> > Duane*

--

Home of the $5 Solar Tracker Receiver

http://www.redrok.com/electron.htm#led3X [*]

Powered by \ \ \ //|

Thermonuclear Solar Energy from the Sun / |

Energy (the SUN) \ \ \ / / |

Red Rock Energy \ \ / / |

Duane C. Johnson Designer \ \ / \ / |

1825 Florence St Heliostat,Control,& Mounts |

White Bear Lake, Minnesota === \ / \ |

USA 55110-3364 === \ |

(651)426-4766 use Courier New Font \ |

redrok@redrok.com (my email: address) \ |

http://www.redrok.com (Web site) ===

> I've just fitted 4 Evergreen EC55 panels to my 24v system. Panels wiredtwo

> series strings in parallel. So, with 220 watts into 24 volts I should be> seeing 9.17 Amps - right?> What I am seeing is a maximum of 5 Amps in very intense Spanish sun,panels

> correctly aligned and all panels producing the same power.> Am I missing something here or are rated outputs fantasy?> TIA, Peter.