Spolar Panel Enquiry

Submitted: Saturday, Jun 28, 2003 at 10:34
ThreadID: 5708 Views:3534 Replies:8 FollowUps:5
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What size Solar Panel would I need to top up my Batteries? I have two 105amp Trojan Deep Cycle hooked up in parallel. They run a 60l Evakool f/f and a fluro that combined draw about 22-24 amp per day. I have no idea with solar equipment so your responese would be appreciated as I am in the market. I have seen one guy camping that had two panels in a box affair.
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Reply By: joc45 - Saturday, Jun 28, 2003 at 12:56

Saturday, Jun 28, 2003 at 12:56
Hope this helps you without the electrical maths.
You can tackle this from a couple of angles.
- One is to use a single panel (say 60watt) as a "top-up", which can keep you going for a few days, before you need the vehicle running to get the battery up. Advantage is cost, but it will hammer your battery, but with your 210 AH capacity, this may not be a problem.
- The other is to fully source your power from the panels. This is much preferred and avoids running the battery into deeper cycles, extending its lifetime. For your type of fridge and flouro, you will need about 120-150 watts of panels; ie, 2 to 3 panels. This takes into account those days when it is hot and overcast. Out put of a panel on overcast days can be 1/4 of that on a sunny day.
You will need to buy a solar regulator. If you can afford the extra, a "smart" regulator which allows the battery to be boosted following deeper discharges is worth having.
AnswerID: 23714

Reply By: desert - Saturday, Jun 28, 2003 at 13:34

Saturday, Jun 28, 2003 at 13:34
All the bloody theory in the world goes out the window when in the real world. Ambient temperatures, battery condition, voltage drops, fridge cycles, etc,etc, it is impossible to calculate for real world conditions. Just buy the biggest mutha you can afford (after all that really is the limiting factor) and suck it and see. If you are happy, fine. If not, you have to spend more on another panel!
AnswerID: 23716

Follow Up By: -OzyGuy- - Sunday, Jun 29, 2003 at 00:01

Sunday, Jun 29, 2003 at 00:01
I agree with Desert's words of wisdom ...
buy one large panel, get a good quality one, if it is not enough get another one, I use one 80 wt Solarex panel, charging direct into 2 Delkor 80 Amp/Hr batteries wired in parallel, running a 50Lt Liemack fridge/freezer set at (0) zero degrees and also recharge lights and radio etc...
simply stated you have to put in MORE than you take out, is that simple.
FollowupID: 15914

Reply By: Botchy Warner - Saturday, Jun 28, 2003 at 15:16

Saturday, Jun 28, 2003 at 15:16
what do you term 'top up'?

In winter from an 80 watt panel would mean realisticly 5 to 6 hours at 4 amps = around 22.00 amps - providing you move the panel during the day for optimum charging.

With winter weather conditions normally 3 x 80w solar panels would be required to keep you charged. 2 x 80w panels in summer would do. 2 x 80w panels in winter with due care to move them three times a day at the correct angle to the sun may just carry you through, but is marginal. If the weather is inclement the 3 x 80w would be a necessity.

Deep cycle batteries should never be used below 50% capacity and preferably 60%.

BP Solar or Solarex (made by BP) Most effecient quality brand.
AnswerID: 23723

Follow Up By: Member - NOBBY - Saturday, Jun 28, 2003 at 16:12

Saturday, Jun 28, 2003 at 16:12
Thanks Guys.. What I had in mind was to hook up the solar panel (s?) as soon as I arrived at the camp and start charging the batteries as the fridge would be running off them. In theory I wanted to put back into the batteries what was being sucked out by the fridge/ lights etc. I would never let the batteries get below 60% as I also have a Christie Gen set. No I have not got an endless supply of $, and I was probably conned into the gen set, but I've got it and it will come in handy at some stage. The bride has gone green ( and I'm all for that) and wants to keep the batteries charged "quitely", hence the solar panels. What would be the approx. price of say 1 x 80/, 2 x 40 in the box affair with stand and reg? Are we talking mega dollars?
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Follow Up By: David N. - Saturday, Jun 28, 2003 at 18:05

Saturday, Jun 28, 2003 at 18:05
If you are only buying enough to top up etc (say an 80w panel) then I wouldn't waste my money on a regulator.... with two 105Amp batteries and using your frig and lites you are unlikely to ever have a problem overcharging your batteries- unless you stop using power and leave the panels hooked up for days. Look at the tasmanenergy site for lots of good info:
also you could talk to Solar panel express or visit their site. (They have a 1800 number. (1800 800 846)
FollowupID: 15893

Follow Up By: joc45 - Saturday, Jun 28, 2003 at 20:00

Saturday, Jun 28, 2003 at 20:00
"Top up" means just that. It will extend how long you can run your battery before recharging it via the vehicle or external charger. I too don't advocate running the batteries down below 50%.
Even with one panel and a 200AH battery, I wouldn't consider running the panel without a regulator. If the battery is fully charged, and there is no load, the panel can still drive the battery voltage over 15v.

I currently run 3 x 43 watt BP panels into a 115AH Trojan battery and a 39l Autofridge, which quotes a consumption of 24 AH per day for up to 32deg ambient (similar to the Evakool). I use 1-2 flouros (0.8A each) each night. In summer, the system copes fine with up to 40deg days provided I don't get more than about 2 days continuous overcast sky.
In winter/spring, the fridge hardly runs, and on a sunny day, the batteries are floating at 14.2v by late morning.

Cost: work on about $1 per watt for panels plus regulator $60 upwards.
FollowupID: 15905

Follow Up By: joc45 - Saturday, Jun 28, 2003 at 23:15

Saturday, Jun 28, 2003 at 23:15
Whoops! I meant max cost of $10 per watt for panels. Small ones around that price, bigger ones less per watt - pays to shop around.

Also, meant to add, friends we often travel with use 2 x 64 watt Unisolar panels, a 70AH battery and a 40 L Engel. Works fine summer/winter, including running a flouro or two at night. This included a recent spell at Ningaloo when it was 42deg, followed by a couple of hot overcast days.
FollowupID: 15910

Reply By: Member - Topcat - Saturday, Jun 28, 2003 at 20:05

Saturday, Jun 28, 2003 at 20:05
Hi Nobby, I run a 190amp deep cycle battery setup permanently connected up to 2X
80amp BP solar panels through a 12amp pulse regulator which runs my 60litre Trailblzer fridge & lighting. Never had a problem keeping my batteries topped up. The setup cost $600 per panel (8 years ago) & $70 for the regulator. I get a good service life out of my batteries too as you can check from previous comments on this forum. Cheers.Have Wheels Will Travel
AnswerID: 23740

Reply By: Member - NOBBY - Sunday, Jun 29, 2003 at 10:45

Sunday, Jun 29, 2003 at 10:45
Many thanks for the replys. All I need to do now is go shopping.
AnswerID: 23761

Reply By: Cocky Warner - Sunday, Jun 29, 2003 at 11:39

Sunday, Jun 29, 2003 at 11:39
If you intend to go in red soil or dusty country do not buy Unisolar panels or any brand of amphourous panel as you cannot get the dust off them. If you leave the panels flat they pool water go soft and damage the coating. I had two replaced by a dealer after I got them fixed by consumer affairs. I paid the extra from the 64 watt Unisolar to BP Solar 80w panels. Three years trouble free and no bloody noisey generators or anything to service.
AnswerID: 23762

Reply By: David N. - Sunday, Jun 29, 2003 at 14:34

Sunday, Jun 29, 2003 at 14:34
I agree- Go for Kyocera, or BP solar or similar- you won't regret it. If you use common sense in how you treat them they'll last forever...

And I still think from what you describe as your setup that if you go for only 80watts of panel hooked up to 2 X 105A batts then you won't need a regulator. A slight overcharge occasionally taking the battery voltage up to 15+ volts is actually good for the batteries- (It's called an "equalisation charge") and from what you describe as your usage patterns it's highly unlikely you'll ever run the risk of overcharging your batteries with that setup! Naturally if you have more solar capacity then a regulator becomes important.
AnswerID: 23768

Reply By: Rod - Monday, Jun 30, 2003 at 14:04

Monday, Jun 30, 2003 at 14:04
I too have a 105 ah Trojan DC, 2 x Versalite Flouros and an EvaKool RF60 f/f. At Easter I ran 2x40W UniSolar panels and was able to run the freezer at -8 for 8 days with no problems.

Ambient temp was around 25-27 during the day. All days were clear and sunny except the last 2 which were cloudy/raining.

I did run the load for 2-3 hours at night from the dual-battery in the 4WD to supplement the battery capacity. On the last 2 nights, I switched the freezer off at night to conserve battery as we had used the majority of our fresh meat.

80W of panels will not run the load forever without vehicle supplement. I think you'd want to double panels for that.
AnswerID: 23850

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