Portable Solar Panels

Hi Kim, If you do a search you will find a wealth of info on this subject. But having said this, to provide the correct answer you will need to advise if the fridges are in the sun or shade,estimated temp and if you will be going for a drive which will charge up the batteries. But a 80watt panel will not cover the enrgy used by the Engels on its own. You will need to run the genny with a (preferred) 3 stage charger to top up.

Regards

Mark

Lots better answers to come but i have 2 x 40watt panels that pull out in full sun about 4.6 amps per hour which is great for one fridge but if running two engels up there in say 40C heat then i await the engel owners (presuming tne newer better insulated models with the 2amp current draw) to see how much they would use. In summary i think with an 80watt panel you'd put enough into the batteries to stop them from draining too much for about a day before you'd be advised to top them up properly. Not a green solution but i think you'd be better investing in a 25 amp 240 volt charger and putting up with the noise for just a couple hours.

Kim,

Firstly, $990 for an 80 watt panel is extortion. The going rate, if you bargain, is about $500. Add on $110 for a regulator and decent cable at $2 a metre.

As for whether it will handle the load of 2 x 40L fridges; there are a lot of varaibles. A Suntech panel in the Kimberley will only work at about 80% efficiency, they drop off when the temp exceeds 25C. Therefore you will only get about 64 watts (about 4.6 amps) whilst the sun is out. Say 8 hours of good sun per day if you are lucky, equals about 37 amps.

Depending on how high you set you fridges they will use diifering power, but from tests these use an average of 1.6 amps per hour. Therefore, 2 fridges X 24 hours X 1.6 amps equals 77 amps. Clearly you will fall short. Probably not by as much as the maths tells you as I have found from personal experience.

I have an 80L Waeco which is supposed to average 84 amps per day, but in summer I can power it happily with a 64 watt panel (amorphous panel that is).

However, you will still be keeping some charge into the battery and will therefore not need to use your genny too often.

Have a look, as an alternative at the Unisolar panels. View the archives under "Jimbo" or "Solar" about December 2004. I posted on some tests I did.

I would suggest start low and see if it works. You can always add another panel. Dealers can, at times, oversell.

Cheers,

Jim.

Hi Kim,
I use an 80 watt solar panel with 2 x 100 amp/H deep cycle batteries to run my 60L Evakool fridge and some lights and find this allows me to be away at least a week without any other form of charging. I live in Victoria and have puchased all my batteries, chargers and solar panel from Solar Panel Xpress in Queensland. They can courier them down here much cheaper than I could buy them in Melbourne. They have a great website with heaps of info (www.solarpanelxpress.com.au).
Owen

We used to travel with a generator, but a few years ago "went solar" purchasing just one 80w panel mounted it on a stand so it be set to face the sun, or put on top of the (stationery) van, depending on time of day, to get optimum sun. We had a deep cycle battery in the van which also charged from the car - but the solar panel did it much quicker than going for a drive. We had 12v lights (more than adequate for reading with) and built in an engel caravan fridge. We didn't meet bad weather though, and were touring mainly in the Pilbara. Often we'd set up the panel facing the sun, go for a walk, and get back late in the day to find it well and truly in the shade, but the battery was fully charged. If the batteries were getting a bit low over night we'd leave the panel facing East, and at first light it would start charging. We run an engel car fridge in the Nissan which has two batteries, and the second one doesn't get drained, so it can be used the jump start the car if the main one goes flat. We never missed the generator at all.

Thanks to everyone for your helpful advice.
Regards
Kim

May I suggest you check my article 'Solar Thar Really Works' posted a few days ago on this site.

Click on 'Electrics' on the 'Topic Search' panel on the left of the page.

Incidentally $880 for an 84 watt module is hugely over the top. Should be closer to $600.
Trust this helps
Collyn Rivers

Thanks Collyn,
I'll have a look at it. Obvioulsy the first two prices were way over the top.
Regards
Kim

We have a 120w Kyocera Solar Panel charging a 110Amp/hr Deep Cycle Lifeline battery. The fridge is an Evakool ED90 (Danfross compressor). In most circumstances the solar panel keeps the battery charged but does not fully charge it. The only time we have had problems is in hot weather and shady conditions.

I wouldn't want to have a smaller panel.

Gaz

The engel 4o ltrs will pull about 3.5 amps each per hour, as a fridge, and will cycle approximately 8 hours in 24. This gives a daily draw of approximately 60 amps for the fridges and lets allow say another 25 for lighting, pumps etc. So, for want of a figure lets say you guys pull about 85 amp per day.

When sizing battery capacities to suit a solar system i work on roughly 4 times the averag daily draw. There are two main reasons for this. The first is the deeper you discharge a battery the less number of discharge/recharges you will get. So, working on this theory you will only discharge approx. 25% per day. The second reason is that in days of rain your system will be able to support itself initially instead of merely collapsing. For these reasons, i suggest no less than 225 amps and will work on that figure for the purpose of this exercise.

The average 80 watt panel will give you approx. 4 amps per hour and this is only for about 6 hours of the day. So lets asssume each panel will give you 25 amps per day. I would suggest two 80 watt panels at a minimum giving approx. 50 amps per day. Bp solar has a rebate scheme going at the moment for any system over 145 amps. You are elligible for 50c's per watt for every panel install so, 2 x 80's will give you an $80 rebate. The panels sell for about $700. Bp panels are the old solarex ones with a few improvements including higher out put voltage (closed circuit) and a silver nitrate backing to prevent energy loss due to heat. Not to mention Aussie made!!!

So, your daily draw is 85 amps and your solar input in the same time frame is 50 amps making your theoretical daily draw now 35 amps.

This means that with no other input into the battery you will last approx 8 days. In saying that you would be better running the generator every couple of days for an hour or two rather then once a week for a whole day. Re: point 1 on battery sizing.

The only other point worth mentioning is charger sizing. This should be no less then 10% of your overall battery capacity. So in your case 20 amps is sufficient. (10% of 225) The reason for this is that if it is too small the unit will never reach 'float' or full as far as the charger is concerned. It will sit there for hours saying "I think i can, I think I can" but it cant!

Any further queries let me know. Nick

Hi guys,

Before I start, i want to thank every body for their helpful advice. I've learnt a lhell ot a lot from the contributions. Your all been terrific.

I've decided to buy a portable 80 Watt unit. The reason for doing so is:

We tend to camp in isolated areas (therefore generator noise is not a problem( except for me).

The units are compact and easy to store

I can move it around to follow the movement of the sun.

Finally, if it doesn't work, I've only got myself to blame.

Hope to see you on the track

Regards

Kim

As previously mentioned I also have a dual battery set up.

Hi Mainey,

Firstly, because of the advice I've received from this site and where its led me in discussions with retailers.

Secondly, as previously explained, we often set up a base camp and could be away from there for well over a week. Therefore, its important I can take the unit with us.

Next year we'll be in very remote country up in the kimberley well off the tourist trail and therefore need to be self sufficient.

Hope I've answered your quesrion

Regards

Kim

Ok.
Hope everyone remebers that you wanted portable! Obviously, all panels are flat and can be stored. There are fold up / briefcase open/shut with little stands types might be ones that were the high price you were quoted.

There are ploy and Amophorous (Can't speel), types. The AM type give out more but wear out over time and don't do well in the heat - most portable types are AM. The polys are better, last longer, and are much better at heat levels.

Previous replies, mention about morning and facing sun and stuff. This is fact: The energy output stated on the panel will be less than what you get. IE: if it says 4amps then you will get (in real life 4.4amps), they are all under rated for legal reasons. But AM types will give upto 30% more, but then go gradually lower (maybe 4 months), as they 'settle in'.

So if you have an 80watt panel which way do you face it? They only get peak power if they are directly FULL ON IN THE FACE of the sun. That's why some rich people have Solar Trackers. But obvioulsy in your case you don't need that - I'm only making a point.

You should only pay for a 80W Ploy panel $600. Get 3 and have one facing the morning sun, the other to collect the midday and the third to collect the setting sun.
if you are around the area, then moving all 3 to face the sun full on as time goes by, then great!
But if you don't want to be moving them all the time, then i suggest the 3 panels. Don't forget that if you get ONE cloudy day, then maybe judge about having a 4th panel to cater for that.
AM type panels are better for cloudy days, but Poly does ok anyway within reason.
That way you cannot go wrong and should meet your power requirements.

As for regulators, thickness of cable and quality of batterys, they all have a percentage of loss and as any good solar guy will tell you - your loss with be at LEAST 50%, for a final power given (what is should give you), to what you need (What you actually get out at the end).

If you have the money and don't care about longivity and a bit lower energy due to 35-40C° days and a working usable life of 10 years, then go AM type. If you want
good all round performance go the Poly type, but i am not sure about the 'portable' side of it.

Lastly, with your roof top quote, just get 2 80w polys and make a frame.

Hope that helps.

Alan.