More solar panels

Submitted: Saturday, Apr 15, 2006 at 06:32
ThreadID: 122608 Views:11380 Replies:5 FollowUps:5
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which is better for solar panels 2 x 120w panels at $1790 or 3 x 80w panels at $1785
prefer to mount 2 panels over 3 panels, but want best result
but which is better for power production the 80w mono crystal or the 120w multi crystal
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Reply By: Tellem Bugrem - Saturday, Apr 15, 2006 at 18:33

Saturday, Apr 15, 2006 at 18:33
G'day Burt,

I'd go for the two because you are sure to want to add a 3rd 120w panel further down the track....and, leave space for a 3rd battery to go with it.

all the best..........Rob
AnswerID: 568364

Reply By: Flipp'n Lorry - Sunday, Apr 16, 2006 at 16:46

Sunday, Apr 16, 2006 at 16:46
I agree with Rob - on our first BT we initially had 2 panels and it was often (not always) a bit of a struggle. Later we added a 3rd and never had any problems.

If you can afford it, go the 3 x 120w straight off - but like all things, it depends on what gear you plan to run. Discuss your power needs with BTI as they have seen all the different combinations before.

AnswerID: 568365

Reply By: Geoff - Monday, Apr 17, 2006 at 21:27

Monday, Apr 17, 2006 at 21:27
Rob has made a very important point. To many of us look towards more power generation without the ability to store it. Lets say you have 200 amp hour storage capacity. You could have a dozen panels but still only ever have 200 a/h available. This is fine until you have a week of bad weather. Your 200 amps runs out fairly quickly. Now lets add a couple of batteries and get a 600 amp hour capacity. This becomes a significant advantage in overcast conditions. You in effect triple your independence. This is not possible by simply adding solar panels. Dont get me wrong, The extra panels do add amps in, which is of particular advantage during overcast conditions. I guess this is just a long winded way of agreeing with Rob. Dont forget the extra battery/s
AnswerID: 568366

Reply By: Burt & Mary - Tuesday, Apr 18, 2006 at 19:00

Tuesday, Apr 18, 2006 at 19:00
many thanks for the info
already have 3 x 110w panels and are going to add 2 x 120
has been suggested we make 2 battery systems
put the 3 x 110w and 200a battery to power fridge only
put the 2 x 120w new panels with 150a battery for house power
if weather gets bad and fridge battery goes low switch 1 of the new 120w panel over to the fridge battery till weather improves
the solar installer suggested this layout and says is common method used for caravans running for long periods on solar
is this good as need to order and pay prior to end of month as solar panel price increase
AnswerID: 568367

Reply By: Bushtracker - Tuesday, Apr 18, 2006 at 19:18

Tuesday, Apr 18, 2006 at 19:18
Hello Burt and Mary,

Don't know who you are or if you even have a Bushtracker, or what the application is. It does not sound like you have been here by the questions, but I don't mind being a help...
Look, I experiment full time, I have three different solar applications running right now on my Horse Truck... I was one of the first to run a large yacht on solar beginning in the 1980's with Arco Panels, and have never quit experimenting. So, enough on my credentials, here is your answer:

Always opt for bigger panels. Every connection has built in losses to the output, and more connections to get more potential problems... As to your question on monocrystaline or polycrystaline panels, forget all the mumbo jumbo and look at heat loss curves. Keep in mind they are not talking about Ambient Air temperature, they are talking about surface temperature on the panels... You can get 50 degrees on some cheaper panels on a 28 degree day.. Do not go for the cheaper common panels, as they suffer more heat loss on output in the hot weather. There is a lot more to this that meets the eye on first go... You need to mount the panels properly, air flow and other considerations, etcetera... I would not go with 120 watt panels, go with the 123 watt Sharp or the 125 Watt Kyocera for best value for money. You will pay a little more, but get better results in the hot weather... Cheap, is not better, and sometimes going just for cheap can not be the best cost effective way to go when you need to live with it long term...

And yes, even more importantly is to match them to the right batteries... I would suggest that this is a study in itself. Heavy plate golf cart type batteries, or normal heavy plate deep cycle batteries will waste about 1 amp in solar output per battery just to "warm the plates" which means excite them enough to begin accepting a charge.. Those type batteries are designed more for 240v battery chargers with a big spikey output to boil them up and clean the plates... There is a lot to this. Gel type batteries accept the charge with about 1/4 of the losses, and are designed more for the solar application....

And yes you need to match about the rate of 125 watt panel to 100 amp hour Gel X Hybrid Absorbed Glass Matt Battery, or regular gel batteries, with thinner plates packed tight, to get the best results..

Too much in solar to too little of battery? Wastes all the solar input from about midday as the regulator will shut down the system with batteries full... Too little solar as in more batteries than panels? Hurts the batteries as you do not get the proper finishing voltage required for maintenance, except maybe in perfect weather... You need to match them, in number, and in type, or you will be throwing money away and not getting the right results...

Yes I am an Expert. No one else would have a frame of referrence of 30 years living with Solar, and a thousand "out there" are running my on going experiments. A Battery company is building our German A-200 Gel X AGM batteries based on our results. Yes we try and do the best job possible. My advice? Don't try and do it on the cheap, do it right the first time...

For Articles on the subject, you can Email me at Bushtracker, I will send them out to you F.O.C.

Regards from the Lone Ranger, "out there doing it full time"...
AnswerID: 568368

Follow Up By: Burt & Mary - Tuesday, Apr 18, 2006 at 20:15

Tuesday, Apr 18, 2006 at 20:15
do have a Bushtracker
"I would not go with 120 watt panels, go with the 123 watt Sharp or the 125 Watt Kyocera for best value for money" what do you call 'cheap' panels? what brand are the cheap panels? I do not think the panels are cheap we want to buy. if you download the specification file for the panels there appears to be no difference. the curves for all the brands are what you could term identical. prior to retirement used to service marine buoys beacons and air nav gear for the feds and this brand of solar panel was the most fitted panel
never had any failures and marine is severe service environment on buoys
presently we are using a Fullriver HL 200 and going to buy a Fullriver HL 150 for the house battery
FollowupID: 845729

Follow Up By: Bushtracker - Tuesday, Apr 18, 2006 at 20:27

Tuesday, Apr 18, 2006 at 20:27
I cannot comment further on Brands, as it is not proper to do so on a Public Forum, but check the Power curves in relation to the temperatures... And then read the small print way on in the printout about surface temperature of the panel not air temperature... Trust me there is a major difference in performance from our experience...

I think I know the panel Brand you are talking about, and they are about the cheapest and most commonly used commercial panel... They work fine for the Government, and are commonly used in applications up on towers and on Bouys and light poles, even on roofs of houses up in racks.... All of those applications up in the air where they have a "Laminer Air Flow" on the back side of the panel to cool them... THIS IS NOT THE SAME APPLICATION OR SERVICE when you mount them flat where they are not up on a pole in the breeze.... And you will get entirely different results when you mount them flat on the roof of your van....

Rather than comment on those 2 Brands and types, I gave you the best types for this application...

Regards from the Ranger, trying it all full time, 24/7, I have made it a "Life Less Ordinary" spiced with travel with horses instead of yachts now...
FollowupID: 845730

Follow Up By: Burt & Mary - Wednesday, Apr 19, 2006 at 05:42

Wednesday, Apr 19, 2006 at 05:42
Bushtracker after been on the phone all day to people at CSIRO and BOM they tell me among the major crystalline solar panel manufacturers there is no difference between BP Suntech Sharp Shell Photowatt Kyocera in performance. They did say Kyocera solar panels have been the only brand that they have made warranty claims on, and to date they have had 21 Kyocera panels replaced under warranty. Dr. Jillian Garbutt emailed me a spreadsheet with the performance of the different brands of panels mounted flat with no air gap and with a 10mm air gap. The performance difference of all brands was within 2% with BP and Suntech at the top of the list. Jillian also pointed out that the construction of all the major brands of crystalline panels was basically identical with a glass front, crystal boundary and Tedlar backing. I asked why they generally bought Suntech solar panels and was told they were generally the lowest cost per watt and performed exceptionally well in marine environments and snow. Gentleman from Sharp told me they bought a pallet of Suntech panels as they cannot get Sharp presently and the Suntech are identical in quality and performance to the Sharp panels. Might as well save $200 a panel. Has been an interesting exercise from knowing absolutely nothing about solar panels now have a reasonable understanding and probably a $150 phone bill.
On what basis did you base your information?
FollowupID: 845731

Follow Up By: Bushtracker - Wednesday, Apr 19, 2006 at 16:35

Wednesday, Apr 19, 2006 at 16:35
"On what basis did we base our .....?"
Measured performance, full light, seasonal variation, temp variations, measured in line output,
Also, Company Performance, service, durability, Warranty service as in when Kyocera had a batch problem..
Resistance to hail damage, and other practical issues... I am not interested in cheapest over a minor amount of money, just the best for something you rely on..

FollowupID: 845732

Follow Up By: Burt & Mary - Wednesday, Apr 19, 2006 at 21:43

Wednesday, Apr 19, 2006 at 21:43
Bushtracker sent your post to Jillian and she phoned me back. Jillian said she has no idea how you came up with your information as she assures me if you compare the major panel manufacturers they are identical in construction weight material composition hail resistance and frame structure. Jillian also said that some of the other big name brand panels (one mentioned starting with a B) are made by Suntech and are identical except for junction box and stickers. Jillian assured me there is no difference from all the testing including hail testing they have done on solar panels between any of the major brands. She went on to say if there was any doubt or quality issue in Suntech panels they would not be approved for use by the department as the standards are exceptionally rugged for marine use. I pointed out to her again about the airflow at the back of the panels and she said they had tested them under these conditions and pointed out to me that on all the marine buoys there is no airflow at the back of the panel. I cannot see Sharp buying a pallet of Suntech panels if they were not up to scratch. Searching the internet cannot find one complaint or problem with a Suntech solar panel. I am not interested in cheap over a fist full of dollars. I am interested in value for money and will be installing the Suntech solar panels. With you saying they are "most commonly used commercial panel" gives me great confidence as commercial and cheap never go hand in hand. it is to expensive for companies to use anything but top line equipment that does not give trouble
FollowupID: 845733

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