Solar Panel Output

[Taylor1992]

So I bought some solar cells off ebay, and have made 3 panels like this one.
(http://cgi.ebay.com/60-Watt-Solar-Panel-12-Volt-Battery-Charge-Controller-/120681203422?pt=LH_DefaultDomain_0&hash=item1c192906de)
So I have 36 cells and the same peak voltage and amperage as the panel above. But it most certainly is NOT 60 watts of power. I can only get a max of 35 watts from each panel because the voltage drops proportional to the load.

So my question is how are the ratings on the solar panels "REALLY" related to their output?
I'm going to go buy a harbor freight 45 watt solar panel kit today and see the "real" output from the panels.

[Taylor1992]

Went to Harbor Freight, and hooked up the panels to my gridtie inverter, and they produced 40 watts according to my kill-a-watt meter. So inefficiencies aside, looks like they do produce 45 real watts.

So the question now is, did I wired my panels poorly, are they just poor quality cells, or everything is right and I was just expecting too much output from this size panel. I used 3x6 cells.

http://www.youtube.com/watch?v=VqASSRWxJG8

[Hoxan]

Went to Harbor Freight, and hooked up the panels to my gridtie inverter, and they produced 40 watts according to my kill-a-watt meter. So inefficiencies aside, looks like they do produce 45 real watts.

So the question now is, did I wired my panels poorly, are they just poor quality cells, or everything is right and I was just expecting too much output from this size panel. I used 3x6 cells.

http://www.youtube.com/watch?v=VqASSRWxJG8

Nice project but, solar panel output depends on brightness of the sun. If there is a cloud output drops enormously.

If you want to use inverter you must have SLA battery. So you need to connect battery parallel to the inverter. Also add some electronics to control charging of a battery.

Charger in series to solar panels => SLA battery => inverter

Some inverters can be damaged if there is no enough voltage/current on the input. Battery reduces oscillations of these parameters.

[Taylor1992]

I'm going straight from the panels to a gridtie inverter. You cannot place a battery in the circuit because it would take 14-24 volts of batteries to activate the inverter, and then the inverter will draw 600 watts worth of power off of them and destroy them.

I live in Florida so it's perfectly sunny, I was just wondering if anyone else made panels from these cells or something similar and what their output wattage was.
It cost me $150 to make each panel, and a 30 watt panel is around that price, but looks smaller when I look at the cell sizes. So I was wondering if a 30 watt panel is really 30 watts is all, so I can stop wasting my time building them.

I built this, http://www.google.com/products/catalog?hl=en&safe=off&q=60+watt+solar+panel&bav=on.2,or.r_gc.r_pw.&biw=1467&bih=645&um=1&ie=UTF-8&tbm=shop&cid=8689413695055111043&sa=X&ei=kew_Tr7ZAeGJ0QH65YnbAw&ved=0CJEBEPMCMAQ

And I'm getting this output. http://www.google.com/products/catalog?q=30+watt+solar+panel&hl=en&safe=off&prmd=ivns&bav=on.2,or.r_gc.r_pw.&biw=1467&bih=645&um=1&ie=UTF-8&tbm=shop&cid=18296256484847166889&sa=X&ei=auw_TrbANMf10gGjm7i8DA&ved=0CJQBEPMCMAQ

Maybe 1/4 inch glass is blocking too much light or the epoxy is blocking some. I'll test it next time I make one and post the results.