Solar Panels, how big?

Moggs e-mail me at landline_equipment at the hotmail company as that is the brand I sell. You could get a pleasant surprise price wise.

You run your business from a hotmail account ! ROTFLMAO

David,

I can't get tour email address from your message. Can you please elaborate or send me a message jimbest at netspace dot net dot au. I'd be very interested in a quote.

Thanks Ray

MadDog you have no idea what you are talking about.
You are incorrect.

Actually, Mad dog is right on the money. You will never get 80 watts of power out of an 80 watt panel.
I have worked with solar panels on and off for nearly 20 years.
You are far safer rating any panel at half the labelled rating to give your self a realistic power output calculation when working out how much power you need.
All of the panels I have worked with state in some for or other, “To get the maximum out of the panel, it should be positioned at 90 degrees to the sun at all times”. Even doing this will not give you 80 watts from an 80 watt panel.
I am at this time testing some new solar regulators and even when tracking the sun, the best I can get out of an 80 watt BP solar panel is 4.5 amps.
For charging a battery that is going to run a fridge and no more than a couple of low energy lights, one 80 watt panel will most likely do the job .
Also consider that there are other factors that will have an effect on the charging, EG. The capacity and condition of the battery.
Just going out and getting a solar panel is not the whole story.
Cheers

Thanks Gents

BP Solar 80w

According to this Drivesafe is right about the BP Solar 80w panel.

Maximum Power (PMax) 80W
Voltage at PMax 17.6 V
Current at PMax 4.55A

ok, it seems you don't want to play anymore tonight so for the benefit of those wondering just how the panels are rated have a look at this site and take note of the 50 millisecond flash.

Go away Ozi

http://www.bpsolar.com/ContentDetails.cfm?page=59

A bit of copy and paste here from BP Solar

How PV Modules Efficiencies are rated in the Factory
PV modules are rated at a well- defined set of conditions known as Standard Test Conditions (STC). These conditions include the temperature of the PV cells (25 C or 77 F.), the intensity of radiation (1 kW/square meter), and the spectral distribution of the light (air mass 1.5 or AM 1.5, which is the spectrum of sunlight that has been filtered by passing through 1.5 thicknesses of the earth's atmosphere). These conditions correspond to noon on a clear sunny day with the sun about 60 degrees above the horizon, the PV module directly facing the sun, and an air temperature of 0 C (32 F). In production, PV modules are tested in a chamber known as a flash simulator. This device contains a flash bulb and filter designed to mimic sunlight as closely as possible. It is accurate within about 3.1%. Because the flash takes place in only 50 milliseconds, the cells do not heat up appreciably. This allows the electrical characteristics of the module to be measured at a single temperature, the ambient temperature of the module/factory. Since this temperature is usually close to 25 C, a minor adjustment corrects output characteristics to the 25-degree standard temperature.

How PV Modules Efficiencies are rated in the Factory
PV modules are rated at a well- defined set of conditions known as Standard Test Conditions (STC). These conditions include the temperature of the PV cells (25 C or 77 F.), the intensity of radiation (1 kW/square meter), and the spectral distribution of the light (air mass 1.5 or AM 1.5, which is the spectrum of sunlight that has been filtered by passing through 1.5 thicknesses of the earth's atmosphere). These conditions correspond to noon on a clear sunny day with the sun about 60 degrees above the horizon, the PV module directly facing the sun, and an air temperature of 0 C (32 F). In production, PV modules are tested in a chamber known as a flash simulator. This device contains a flash bulb and filter designed to mimic sunlight as closely as possible. It is accurate within about 3.1%. Because the flash takes place in only 50 milliseconds, the cells do not heat up appreciably. This allows the electrical characteristics of the module to be measured at a single temperature, the ambient temperature of the module/factory. Since this temperature is usually close to 25 C, a minor adjustment corrects output characteristics to the 25-degree standard temperature.

How PV Modules Efficiencies are rated in the Factory
PV modules are rated at a well- defined set of conditions known as Standard Test Conditions (STC). These conditions include the temperature of the PV cells (25 C or 77 F.), the intensity of radiation (1 kW/square meter), and the spectral distribution of the light (air mass 1.5 or AM 1.5, which is the spectrum of sunlight that has been filtered by passing through 1.5 thicknesses of the earth's atmosphere). These conditions correspond to noon on a clear sunny day with the sun about 60 degrees above the horizon, the PV module directly facing the sun, and an air temperature of 0 C (32 F). In production, PV modules are tested in a chamber known as a flash simulator. This device contains a flash bulb and filter designed to mimic sunlight as closely as possible. It is accurate within about 3.1%. Because the flash takes place in only 50 milliseconds, the cells do not heat up appreciably. This allows the electrical characteristics of the module to be measured at a single temperature, the ambient temperature of the module/factory. Since this temperature is usually close to 25 C, a minor adjustment corrects output characteristics to the 25-degree standard temperature.

How PV Modules Efficiencies are rated in the Factory
PV modules are rated at a well- defined set of conditions known as Standard Test Conditions (STC). These conditions include the temperature of the PV cells (25 C or 77 F.), the intensity of radiation (1 kW/square meter), and the spectral distribution of the light (air mass 1.5 or AM 1.5, which is the spectrum of sunlight that has been filtered by passing through 1.5 thicknesses of the earth's atmosphere). These conditions correspond to noon on a clear sunny day with the sun about 60 degrees above the horizon, the PV module directly facing the sun, and an air temperature of 0 C (32 F). In production, PV modules are tested in a chamber known as a flash simulator. This device contains a flash bulb and filter designed to mimic sunlight as closely as possible. It is accurate within about 3.1%. Because the flash takes place in only 50 milliseconds, the cells do not heat up appreciably. This allows the electrical characteristics of the module to be measured at a single temperature, the ambient temperature of the module/factory. Since this temperature is usually close to 25 C, a minor adjustment corrects output characteristics to the 25-degree standard temperature.

Mad Dog, don’t waste your time. You, Utemad, myself and most of the people on this site are here to help one another with nothing but satisfaction as our reward.

He’s only here to make a buck and as he is not much of a salesman, the only way he can try to do that is to attempt to make himself look good by trying to belittle others.

Utemad has already given the stats for the BP panel and if one reads the treads further down this posting you will see that the rocket scientist himself states that the panels at best only turn out 4.7 amps.

What our learned friend obviously does not know is that 4.55 amps at 17.6v will still be 4.55 amps at 12 volts, which is the voltage that everybody else on the site is interested in. The problem is that our math illiterate friend can’t work out that 4.55 amps at 12 volts amounts to only 55 watts.

There are a few other factors that come into play that will move the wattage up or down but for most people reading this posting, a basic reliable calculation is what they want.
This has been done by just about everyone but the rocket scientist, his motto is “If you can’t dazzle them with brilliance, baffle them with bull s##t”
Cheers all.

My understanding was always that volts x amps equals watts so I had figured an 80 watt panel charging through a regulator would produce about 5.5 amps in much the same way that 1 amp at 240 V put through a transformer (ignoring heat loss) would produce 20 amps at 12 V.

Is it a different issue with panels?

Be gentle with me fellas, I'm just asking questions, not questioning anyone.

Cheers,

Jim.

Hi Jimbo, yes you can get more than the 4.55 that I posted.
If you use a Switched Mode Regulator, at 14 volts you should be able to get a tad over 5 amps, but remember, this is with everything in a best operating situation.
The thing to remember is that you should really calculate your requirements based on being able to get about half the optimum output of the panel.
This is a rough rule of thumb but it allows for cloudy days and other factors to have less of an effect on the long term operation of what ever you are using the gear for.
For anyone thinking about using solar panels, it would pay you to seek the advice of a REPUTABLE solar expert. Make sure who ever you speak to is a certified R.A.P.S. installer, they SHOULD be able to give you authoritative info.

Yeah you can't change Ohms law can you Jim. I guess the ideal conditions in the lab don't often occur in the wild but really you should be more concerned with how many amp/hrs you will collect over a day rather than the peak amps. Drivesafe appears to have his finger on the pulse. I'm just a hacker who plays with panels in the backyard

Thanks John,

If this is about what a panel can do, it will suit my needs.

Utie,

According to the manual for the CF 80 it averages 3.5 amps running as a fridge and freezer, holding 5 C in the fridge section at 32 C ambient.

Also according to the manual if you switch it to the low setting it draws 36 watts (3 amps). I run mine as all fridge on the low setting and it is off cycle more than on. That's how I calculated 1.5 amps/hour. I've run it as a fridge and freezer and it draws heaps more. I will only use the freezer if I need to and expect it to use a lot more than 1.5 amps/hour.

Cheers,

Jim.

I was just making sure you realised that over a one hour period your fridge would draw 3.5amps (according to the manual) not 3.5 amps 30% of the time and near zero amps 70% of the time.

Sounds like you know that already though from your followup.

I ran mine on 5 lights last weekend and it was about 35deg in the back of the ute wth -10deg in the freezer section and it certainly sucked the power.

I bought a windscreen sunshade during the week so I'll have to start making my fridge cover when I get home :-)

Utie,

I ran mine originally on 4 lights at about 25 C, it held -10 c in the freezer and drew heaps of power, as you have experienced.

I got a windscreen sunshade and duct taped carpet underfelt to it in three sections and it sits over the back, top and front of the fridge. Seems to help and I will try to measure it at some stage. I also have another windscreen shade which I suction cup to whichever window the sun beams in through.

Thanks Darren,

I'm not looking to stop anywhere for days on end, I never go anywhere without going for a drive at least every second day. I'm just looking for something that will stop my need to idle the car three or four times a day to keep the batt topped up.

Do you reckon a panel will do that?

As for the fridge, see my above reply to Utie.

Not sure if I'm right but it is as near as I can calculate.

Out of my 2 batts I get 2 days and 2 nights normally, not worrying about what is running, and with a gennie I can park anywhere, like in the shade, and the weather wont matter, and dont have to move the panels for optimum, but the 2 panels allowed me to stretch this another 2 days normally without running the car.

When i compared the panels I had in cost to a generator, after trying them, I came to the conclusion I was better to get the good quality quiet gennie [has more uses too] and spend the $ left over i saved from going gennie from panels on something to keep cool in the fridge.

Maybe if I lived in Qld instead of Vic, it may add up, but still a glass item, that only has one use, compared to a gennie that needs them to be in the sun.

What sort of output has your gennie? I was lead to believe they only put out about 8 amps, which I considered would need to be run 4 or 5 hours per day.

Right or wrong?

What sort of gennie?

I havent settled on one yet, as afew things going on, but a Christie gennie may do the job, especially if modded to take some stuff Im looking at importing, along with the MOFSET battery isolators.

welders and power supplies

I have got a bushranger 4000 at the moment into the acc plug so it charges while driving, is seperated when acc off, which acts as a 3rd battery at the moment, which has filled the gap currently.

I did have 5 batteries in the car at one stage, with a 4.5kva gennie, and battery charger to run the wifes dialysis machine for 10 hrs per night, before she had the transplant, and would charge them as a bank during the day, so we could still go away, also ran the microwave from the invertor [big 1500w sine wave it was] for heating dialysis fluid, cooking tea 8-) etc, from the same bank.

Havent found the perfect set up for what i do yet, but getting closer.

Buggered if I can understand that site. What exactly does that contraption do in regard to charging batteries?

Also when you say bushranger 4000 running from the acc plug, what is this? Some sort of in car battery charger?

Trust your wife is well now?

Truly a pleasure having decent conversation with you.

All the best,

Jim.

they make welders and power invertors which run from the alternator, hence why the Christie Engineering gennie may be the choice for me, as a generator, than a little petrol motor powered invertor style.

christie gennie

The bushranger 4000 is a battery pack maxi 4000

Thanks Darren

just set 1x75 panel up in back yard. overcast day no shadows
getting up to 2amp

Thanks Brian,

When you say 2 amps even when overcast, does that mean you will get 2 amps for 14 hours per day in the summer. If so I would be laughing. 28 amps would do all I need.

David,

I'm assuming that chart details average amps per hour per day according to the month, but for what size panel and how many houe=rs per day?

Jimbo that chart details the solar hours per day for each month.
That is the amount of hours a solar panel will charge at maximum power.

Why does Geralton WA get 1/2 hour less sunshine than Broome WA when Broome is 2,500Klms further north and closer to the equator ???

Thanks for effort Blackie, but that link didn't work for me.

.com not .net