Looking for table that has common pv panel size, weight , ptc rating etc

System

I'm just starting to plan a system for my small house in Oakland Ca. I would like to know panel manufacturer, model, panel dimensions, weight, power output, ptc rating, etc so I can estimate array size needed for my small roof. The California solar program list approved panels, but the table doesn't have size or weight.
http://www.gosolarcalifornia.org/equipment/pvmodule.php. I know I have a limited area, so will need high output panels. I understand that Evergreen is the most recommended choice - any place that just lists the Evergreen panels without my having to drill down to each model's detail to find size & weight?
Thanks

BB.

Re: Looking for table that has common pv panel size, weight , ptc rating etc

Hmmm... The "type" of panel (Mono Crystalline--smallest per Watt, poly crystalline, amorphous largest panel per Watt) will sort of set the "square footage" of solar panels.

If you want to get the most power from your roof, then choose mono-crystalline (I believe, from another thread, Evergreen panels are poly crystalline). However, mono crystalline will probably cost you the most money.

Amorphous are the cheapest per Watt, but their panels are much larger square footage per watt output. Also, they tend to have a shorter warranty.

Regarding the weight of the panels... Panel Weight should not affect the design of the panels on your home--The roof, racking, bolt downs, etc. are designed to withstand wind and snow loading--which is much larger than the static weight of the panels themselves.

The only, typical, weight issue is that the larger the panel (wattage/sq. footage), the heavy they are. A BP 4175 (175 watt mono-crystalline panel) was light enough for one person with a rope leaning over the edge of the roof to hand over hand hoist them up. A 250 watt panel may require something more sophisticated--or more people to lift/control. (and--you have to watch on a windy day that you or the panel don't get blown off the roof).

Just some numbers to see what we are typing about. A BP 4175 panel (PDF Download):

Length: 1595mm (62.8”) Width: 790mm (31.1”) Depth: 50mm (1.97”)
Weight: 15.4 kg (34.0 pounds)

Static load front and back (e.g. wind) 50psf (2400 pascals)
Front loading (e.g. snow) 113psf (5400 pascals)
Hailstone impact 25mm (1 inch) at 23 m/s (52mph)

For example, the panel physical properties:

62.8"*31.1"/144sq"perfoot= 13.56 sq.ft.
34lbs/13.56sqft= 2.5 lbs per sq.ft.

But, the panel will take wind (both front and back) and static loading of 50 lbs per sq.ft.

13.56 sq.ft.*50psf= 678 lbs of force against racking and roof

Snow loading:

13.56 sq.ft.*113psf= 1,532 lbs of force against racking and roof

So--from the above numbers, a panel weighing 2.5 lbs per sq.ft. +/- is nothing compared to 50-113 lbs per square foot of force supplied by nature...

Or the fack the racks+roof structure have to not support a 34 lbs panel, but upwards of 1,532 lbs of solar panel (for a 175 watt model I have here).

So--other than trying to workout how to rack each panel up (and leaving room for hardware access)--the calculations that your building department will require--must be done by a licensed civil engineer.

Lastly, much of the stuff can be done as a first estimate as a rule of thumb type calculation. For example, find a panel and setup an equation (use the BP 4175 panel as an example--I like to use the Xantrex Sizing Calculator as it has a huge number of solar panels and their basic electrical specifications, so you can quickly compare different panels and setups--and it has the PTC rating too, both for the panels and the overall system):

PTC/STC for the BP 4175= 155.2 PTC Watt / 175 STC Watt = 88.7% derating

For example, my system is 2 strings x 10 BP-4175 panels on a GT 3.0 (3kW) inverter.

STC of panels 3.5 kWatts
PTC of panels 3.104 kWatts
CEC of system 2.933 kWatts

All of the major panel vendors and GT inverter vendors have similar designs and ratings... You can start with some "rules of thumbs" to get close--then do the exact calculations on a couple designs--to save time and energy.

In reality--don't get too involved in the very detailed specifications. You will not even be able to "see" / measure a +/-5% difference on an installed system without using laboratory grade instrumentation.

Just use the "standard" numbers and tools to design / compare your systems--at least all of the assumptions/conditions are pretty much the same across all vendors--so you can compare their specific differences ($$$/Watt and $$$/kWhr of production).

Generally, the larger panels will probably be more efficient per installed square foot, and cheaper to mount and wire (fewer panels and connections). Also, larger panels can have lower $$/watt pricing.

Lastly, when you find some vendor's panels on sale--check that they have the UL/CSA/NRTL certificates (should be marked on the panels themselves)... It is not that the "sale" panels are built any differently, but sometimes vendors will sell on the secondary market their panels without the NRTL marks (preserve their normal channel pricing).

For somebody doing Off-Grid installation--they won't care. But if you are doing a Grid Tied system--your building department, utility, and insurance can give you grief it they check (or check after an insurance claim) if the NRTL marks are not there (UL was started by insurance companies to reduce their exposure to losses and make for safer homes/workplaces).

Otherwise, I would be doing the same as you... Googling a Brand Name and Model number--and downloading the Specs.

In generally, doing a Grid Tied installation is not something for the first time do-it-yourselfer--you need a licensed electrician, a civil engineering contact, etc... After you have seen/helped one or two systems installed--it is not difficult.

This is a pretty generic answer... Do you have other questions?

-Bill

niel

Re: Looking for table that has common pv panel size, weight , ptc rating etc

tc,
i don't recall seeing a website that lays the specs for many pvs out. i guess you'll have to do some detective work yourself when looking up these specs. many pvs give their efficiency, but you can roughly figure that for yourself if they don't show it for some with the power delivered per sq inch.
as for the weights of the pvs, you'll find that most of them have appreciable weight and a few pounds either way may not make that much of a difference. your big concern may be if your roof can handle the weight and even the stresses of the winds upon the pvs as it could make like a sail pulling upward on the roof.

System2

Re: Looking for table that has common pv panel size, weight , ptc rating etc

Bill and Niel, thanks for the very informative replies. My concern about the weight was mostly about whether I could get a panel up on the roof by myself - 35lbs would be ok, but 40+ would be iffy. I don't want to do it myself, but I want to at least scope it out so I know what is practical. Our house was denied recently as not doable by a 1BOG contractor who did a satellite inspection and would not come out to the house.

After that I started googling, and found a diy video that was encouraging:
http://www.archive.org/details/DIY_self_installed_solar_photovoltaic_panels

I know the sun patterns on our roof and think it is doable, though it would take 3 or 4 strings, with the biggest ones on the north side of the roof. We have a section of north roof with a rise of 2/12 and a surface area of about 12 ft x 8 ft. There is another north section of about 18 ft x 12 ft with a rise of 4/12. I think arrays with a reverse slant would work. Once I work thru it myself, then I will talk to a local pv contractor.

You've given me enough info to get started. Thanks again.

niel

Re: Looking for table that has common pv panel size, weight , ptc rating etc

don't be too quick to jump into it as there may be some validity to what that contractor said. 2 questions: 1> did he state in more detail the reasoning for the refusal? and 2> what is BOG?
you state the placement of the big pvs to be on the north side of your roof and if that's to mean facing north then it won't work. you could get another opinion too by somebody that will look in person and do the necessary testing if he thinks it's warranted.