Choosing the best solar panel

1 Posts
Aug 7, 2006 09:46 am
Choosing the best solar panel

I am in the process of picking pv panels for producing most of my own electricity (approx 88%). I am getting a number of different quotes from various installers on different types of panels. So far I have been quoted on Schuco, SunPower, Evergreen, Sharp, Sanyo and Schott. Frankly, I find this process to be a bit baffling. If one installer is quoting Schuco panels and another is quoting Evergreen panels and the price is similar,assuming at same wattage, how do I choose which panel to go with? I have not found a location that reviews each different panel in relation to each other. Before I make my final decision, I would love to read some sort of objective review of each panel. I'd like to know such things as their durability, warranty,
any problems incurred, where they are made, and of course their efficiency. Right now it looks like I'm closest to choosing either Evergreen or Schuco panels.If anyone is out there who can either give me their own opinion or steer me towards a place where I can get this type of information, I would really appreciate it. Thanks very much.
8 Posts
Aug 7, 2006 11:20 am
Re: Choosing the best solar panel

If you are going by brand,Evergreen or SunPower are very good panels.Both companies manufacture their own cells and are known in the industry as being innovative in that field.SP actually is the only manufacturer who makes back only contact cells with no aluminum grid which cuts conductance losses because the full face is utilized for solar collection.Their modules are more but the added effeciencies are worth it.(Think their guarantee is 80% of power for 25 years)25 is pretty standard now with encapsulation so i wouldnt worry about lifespan but an fyi would be to go to the nearest dealer with a multimeter and actually field test the modules you will be buying.
Guess you could look at SP and Evergreen as the Apple panels of PV and Kyocera,et al as the Dell or Lenovo of PV.
If you want comparisons,NREL(National Renewable Energy Laboratory) still does walkthroughs on production floors and independantly tests all manufacturers modules.    will have to search for the STC comparison charts...
13 Posts
Sep 7, 2006 09:28 pm
Re: Choosing the best solar panel

Best panels here for the price are the Evergreen, They are Pre-wired very sturdily, connectors are very positive. Evergreen Inc is getting very good rating for their innovation and technology. Mine perform right on the money......
578 Posts
Sep 8, 2006 01:53 pm
Re: Choosing the best solar panel

If it was my money, I would look for something UL listed, with the best warranty.  Sun Power does interesting stuff, but they only work with positive ground systems, and that requires a lot of extra work.  You are pretty safe with any of the name brand modules.  The sanyo are nice, but the technology is new, and the warranty is structured slightly differently than most other manufacturers.  I am partial to evergreen, shell, isofoton, kyocera, and unisolar, but that is just me.

-james Alt-E staff

"Making Renewable Do-able"

Tel: 877.878.4060 x107  or +1.978.562.5858 x107
Fax: 877.242.6718  or +1.978.562.5854
Sep 9, 2006 08:18 am
Re: Choosing the best solar panel

I am to late with this bit of information I am sure. I am surprised that no one mentioned it really. Its climate and average ambient high temperature for your region vs. PV module rated voltages. Yep! voltages, plural. There are three different voltages to one PV module.
1. the nominal voltage.      for example 12
2. the open circuit voltage.             21
3. the working or voltage.               17
Its the last one, the working voltage that is an issue with your regional climates average ambient high temperature. The higher the temperature say, if its tropical for example, then the higher the working voltage should be. Something in the order of 18 vdc or even 23 vdc for example on a 12 vdc nominal system. In contrast if its a colder region like Northern Alaska one might get ample power from a 14 vdc or 16.9 vdc module on that same nominal 12 vdc system.
By why would you want to?
If the higher voltage works so well in the heat then its really going to crank out the power in the cold!

Some of the first "modern type" PV modules I ever bought where the Solarex MSX77's with a working voltage of 16.9. When I say modern type, I am referring to those that came with frames, j-boxes, and warranties of course.
On the particular system these where working on, during the summer they didn't have an easy time of recharging the battery up to 100% each sunny day and one could forget about equalizing. While during the winter, they excelled at charging and they could equalize. This is in the southeast region of the north American continent.

The gist of all is - the hotter a PV modules gets the lower its working voltage gets and this goes for all PV modules.
I am truly surprised that the PV industry is not incorporating some sort of thermal electronics to the back of PV modules in an effort to generate even more power from a single PV module. Of course this would drive the cost of an already over priced item even higher.
1 Posts
Sep 11, 2006 12:28 pm
Re: Choosing the best solar panel

Now that performance vs temerature is brought up, what about the temp specs ?
Many panels have specs for ambient temp in the range of
-20C to +40C.
What happens below -20C. The temperature may go down to -40C during the night in the dead of winter. The panel is not operating at this time. When morning sunshine hits it, it will be very cold for a little while until the sun warms it.
What happens below the manufacturers stated temp range ?
578 Posts
Sep 11, 2006 01:33 pm
Re: Choosing the best solar panel

what happens is that voltage goes up.  40 degres C is not super unusual, and is covered by the national electric code.  a factor of 1.25 times voc is taken for temperatures between -21 and -40 degrees C.  check out NEC section 690.7 for further details.

basically this correction is used to size charge controllers based on estimated pv output, along with extremes.  with this correction factor, you can make sure you dont blow up your charge controller on the coldest, sunniest days.

- james Alt-E staff

"Making Renewable Do-able"

Tel: 877.878.4060 x107  or +1.978.562.5858 x107
Fax: 877.242.6718  or +1.978.562.5854

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