Solar Panel types

[Capt Slog]

I've read that there are (basically) three types of panels available, monocrystaline, polycrystaline, and amorphous.

And I've also read that are advantages and disadvatages to each, but would like to know a bit more from someone who is using them to find which is the best for me.

I want to buy around 80w, they'll be on a fixed location (no tracking possible) facing due south at around 45 degrees tilt.  The weather here is very mixed, it can be quite hot in the summer, 80C sometimes but lots of the year it can overcast.

I'm using 12v batteries, and have a small turbine on them at the moment.  The power will be used mainly for lighting, and that will be mostly LEDs

I'm thinking that amorphous panels might be best for me, and would like opinions.

I apologise if this is already on the board somewhere, please just point me in the right direction.

[DamonHD]

In addition to your categories I'd slide in 'hybrid' and/or 'multijunction' such as the UniSolar panel I already have and the Sanyo HIT panels that I've just ordered for my grid-tie system.

Both of these claim to do better in diffuse lighting (ie manage to use the red end of the spectrum) than plain silicon cells, and to work better in the heat.

You can probably find a single UniSolar panel near your 80W target for 12V nominal applications such as yours, and when I last looked UniSolar (from MidsummerEnergy) was the lowest £/Wp that I could buy (which is why I have one!).

Rgds

Damon

[ghurd]

I hope 80C is a typo!

I don't care for the amorphous because I see so many fail before their time.

That said, there isn't really a lot of difference in the output under similar conditions.  If a 1A panel is under conditions where it makes 1/2A, then other types of 1A panel will make about 1/2A too.

Be sure to leave a lot of room for circulation under them. 10cm min.  I usually go about 20cm.

The angle needs to be steeper, 60 degrees?

G-

[Capt Slog]

Yup, it was a typo.  I get so used to Celcius/centigrade that I forget.

I'd not considered a circulation gap under them, thinking anything the wind will get under must lead to trouble.  I suppose that this is for cooling?  such a shame that they don't make them with a water jacket so you can take the heat off as well.

The 45 degree slope is not changeable I'm afraid.  That's the slope of my shed roof and that's where they'e (it's) going.

[ghurd]

They will 'burn' if there isn't enough circulation.

They change colors and don't work as well.

Just make the high side legs taller than the low side legs.

I could upload a pic or 2 of how I make them, if it would help.

G-

[DanG]

As Ghurd says, heat is the enemy of PV materials plus output is reduced .05 to .08 volts per degree Celsius heating, with current dropping a smaller amount. In cold climates people get used to high winter outputs since the exact opposite is true, .05 to .08 volta gain per C° decrease, and then feel 'panel poor' during summertime. Add 20°C extra heat to the panel and you can see 1 1/2 output volts vanish. If your maximum power point is 17V and you're suddenly seeing 15.5V all the other parts of the system become MUCH more critical, fuse, shunt, wire losses etc...

About leaving room 'behind the panels' - the sunlight energy making it onto the actual wafer has only 12-15% converted to electricity. The rest is either absorbed or bounced back skyward, the part that was absorbed having to go somewhere via conduction, convection, or radiation. Since the panels themselves have such low mass there is little conduction, and convection via heating air transfers a smaller amount from the smooth glass or the smooth back-plane panel than you would expect.

A majority of the panels peak heat will be shed via radiated infrared light which you don't want to mirror back at the panels from the roof or ground to be reabsorbed generating stronger IR which gets mirrored back etc.. Having the panels lifted well above the roof surface AND at a slightly higher angle will allow radiative cooling to be more efficient. Also allow room for more panels as your system grows that won't be in the area the diffuse  glow' of IR light shed by your first sets of panels...

Solar energy is a process. Buy the very best and SOMEONE may see 30-50 years use out of it. Mono-crystalline will have best resale value when you trade up, get a popular name brand panel and someone will snag it up when you're done with it so they can add the identical panel to their existing array...

Sorry to have written a book - that extra cup of coffee got me wound up : )

[Flux]

My experience has been that amorphous cells seem to have a life of 10 years or less. As they are only marginally cheaper than mono or polycrystalline I have come to regard them as poor value.

Flux

[ghurd]

What I do doesn't worry about the couple volts lost in summer.  Proper wire, good controllers, and a lot more sun more than make up for it.

I'm more concerned with them failing due to burning.  That is usually NOT covered under warranty, and called Improper Installation.

Winter means less sun. The lights are on more.  Not getting the PVs up to 60 degrees is going to hurt the winter output a lot.

(Capt- Shoot me an email re:Schottkys)

G-

[electronbaby]

I tend to gravitate toward mono. I live off grid so I say this because the mono generally has a longer power lifespan in a battery charging application. and yes, the resale is often higher. They are generally more expensive from the start however. I have no problem with poly, I have installed roughly 150,000 watts of poly over the past couple years. I am VERY happy with the Kyocera GT modules as I often see 20% over the nameplate rating into the batteries with an MPPT controller. I still cant get over this. However, they have had their problems in the past. I think the whole industry is on a big learning curve. Its constantly changing. Been doing some of the new Sunpower mono's too. Pretty module. Not sure they are the most efficient though, the HIT sanyos have them beat in a yearly average. The company is also not that old. They have had lamination problems in the past due to black backing laminent.

The solarworld module is the old siemens mono. I have a bunch of siemens monos and i like them (SP-150).

[ghurd]

I was just looking into the Sanyos.  They better work at night for that kind of money!

They are 22% more money than a 5% larger BP.  28% more money per watt.  They can't be that much better in low light!  I'll take 28% more watts of regular multicrystalline panels any day.

Just teasing.  I know the UK has pricing a lot different than the US.

G-

[electronbaby]

Last time I checked, the sanyos out perform the sunpower mods in averaged yearly production. Its because they are hybrid amorphous/mono. Ive installed alot of the HIT's and they are really cool. They are pricey, I agree. I seem to remember the warranty has something to do with humidity. Its wierd. dont quote me on it, but they wont honor the warranty if the humidity is over 65%

Im going to have to re-read it.

:-)

[offgridman]

If all you plan on buying is 80 watts then I would buy Mono, Poly in that order based on the best price per watt I could find.

If you intend on expanding then buying a standard size standard brand is more important since you can add on later as your system and system volatage grow and change.

My cabin is off the grid and kludged from used and new panels of all three types (Mono,Poly, Amorp)of panels.

I like Mono and Poly equally well

Amorp type is not as long lived so I am told. Mine still work well though after 9 years. They could have degraded some but I not longer check them that closely.

If you plan on staying with this then go ahead and buy something like a nice morniningstar charge controller now. I purchased several cheaper ones wasting money as my system grew.

I know this is hard to accept and I did not follow this advice but consider setting up a higher system voltage right from the start. The savings in wire size and losses from wire resistance are well worth the extra few dollars and trouble from the on set.

That said I still have a 12 volt system on due to the hodgepoge of panels I have.

 ( I am not able to balance my panel output easily so I stay at 12 volts)

I have a 3Kw inverter, a 600 watt sine wave inverter, and a 500 watt inverter on my system.

Having the small 600 inverter allows the TV and lights and fan to run all night without a high stand by load. The 3KW takes care of hair dryers, coffee pot, microwave, ceiling fans etc the rest of the time.

I run 10 6 volt batterys and got five years off the first set. I just replaced them a couple of months ago.

My two cents

Offgridman