Can't help with solar, so what am I doing here?
I'm here to welcome you to the Grey Nomads forum.
I hope you get help with the info you seek. Safe and happy travels.

Find out what your battery capacity is, and divide it by 2. You normally don,t want to drain your batterys past 50%. See how big the solar panels are, in watts.If your batterys are 120 amp hr , and you have say, 120w panels at 18v, the panels will put out aprox 6 amps in full sunshine, for 7 or 8 hrs per day.So they are putting 42 plus amp hrs into your batterys per day.See how much your fridge and lights draw and try to balance it out.If it doesn,t balance you need more panels.I don,t think you can have too many panels. Also you need a voltage regulator bigger than your total amps output. This is just an example, but I hope it helps you.

-- Edited by bill12 on Tuesday 26th of April 2011 12:56:18 PM

Thanks , Everone is so helpful, i need to do a little more maths.

Cheers

jimricho wrote:

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Welcome to the forum Shane,

I just had a look at the site recommended by Jack Biggles http://hobohome.com/ (click on the underlined link it'll take you there)

There appears to be some excellent and comprehensive information there and answers many questions that are often asked on this forum.

It's a handy one to bookmark (or add to favourites)

Jim

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 Jim,

If you go onto other forums and this topic of solar comes up, you end up in the middle of wwIII with various know it alls bickering over this and that.

I have my own opinions about solar and how it should be done but I rarely share too much info & stick to answering specific questions.  I don't like getting into debates over how long a peice of string may be.

Some time back I actually contacted hobohome & asked Gavin there a question and he was very kind to respond in great detail.  I have found that he has both the qualifications AND EXPERIENCE of living with solar for many years.  So he's got the trade and the runs on the board.  He goes into great detail about wiring and connections.  VOLTAGE DROP is a great killer of solar, as is mismatching stuff.

I have found it best to do all the research you can, arm yourself with as much information then go and see 2 or 3 different professionals, after which AND ONLY AFTER WHICH you can make the best decision to suit YOU!

Anyway, its lovely chatting with adults about the topic and I am sure theres more than one way to skin a cat when it comes to solar.

 

regards

jack

Hi Shane

A book that is worth getting is Collyn Rivers "Solar that really works".

Here is a link to his site.

http://www.caravanandmotorhomebooks.com/books/index.htm

Regards Jim

Hi Gypsy Chris,

Please take the time to read the information on hobohome.com & also that link above to Collyn Rivers site.  Collyn is another man with considerable experience in the field.

I think solar is one area where people can do really well for themselves or really badly. Each system needs to be designed for the individual user, theres no point spending $20,000 on panels and batteries & chargers etc when a system 25% of the size will do the job.

I have always personally added a percentage of overkill to my system regarding size of panels etc, which is great to have when you are in the southern parts of the country (where there arnt as many SUN HOURS) OR for poor weather (rain etc).

Bill raised a point about batteries being able to be drained down to 50% of their capacity, however I don't like to go that low because most batteries have far many more cycles if you only drain down to about 70% of the capacity.   I prefer AGM (Absorbed glass matt batteries) as there are some really good models available now, they accept both a fast charge or slow one, they go okay in the heat of our northern climates but I will never place one near a hot engine or turbo again. (HEAT is one of the biggest killers of batteries).  AGM are reasonably priced & if used correctly you can get many years of use out of them.

I also feel that people should monitor their battery levels closely & try to understand what is going on with them, there are devices that do that for you.  Most batteries will also benifit from a good solid charging from 240 volt or even generator sorce, about 1 time per fortnight/month, as this assists with preventing sulfaltion, which is another great killer of batteries.  It pays to have a good quality multi-stage battery charger.

Most importantly, as both hobo & Collyn will indicate, wiring of the correct size is so very very important.  Many people fail in this area with inadequate wiring/connections & voltage drop causes many problems.

Anyway, thats more than enough from me, I can't back up what Im saying with any paper qualifications only some experience in use & the rest is information I have gleened from 'others'  who are apparently qualified to state so.

I am in the process of building a new van & have put considerable effort into the solar side of things & am looking forward to using the system in a couple of months time.  I guess after that I will know if I got it right this time, or at least what NEW MISTAKES I have made 

Chris,

If I were you, I'd take a pen & pad & ask them what they can do for you.  Tell them to be specific in their reply & write down everything they say.  Ask them what they are going to use.  Make some questions before you go, so you dont forget.

Ask,

1. What panels (Brand, type, size)

2. What batteries, Brand, type, capacity.

3. What solar regulators?

4. What charging device?

5. What monitoring device?  Its much easier for a device to measure what goes into and out of the battery than you trying to guess whats going on.  Some systems have the ability to monitor it all & provide you with various details including history etc.

6. Where are the panels going to be located & information regarding longest length of cable & size thats going to be used etc.

7.  Theres other things you can do such as running a 'hotwire'  from your vehicles charing system down to the rear car & put a Anderson plug on the rear of your car, then another lead on the van with Anderson plug, that way you can get a charge from your car as you drive etc.

 

*  After the so called expert answers your questions take the information away and do some research of your own, work out what voltage drops you are going to get with that system and so forth. & thats all before you part with the precious $$$$$$.

 

Of course you will need to tell him what your power requirements are, ie: What fridge, size and type, what lights, pc's usage, telly etc.

 

Make sure you build a system with a bit of redundancy, for example, if you think you need 100 amp hours per day, build a system thats 40% bigger than that.  That way, during overcast weather, or pehaps when you are in the southern parts of Oz where the REAL SUN HOURS are significantly reduced from the northern parts, your system still has some chance of coping.

People often confuse what sun hours are.  They think that when the sun goes up and down then thats the hours of charge, but thats not so.  I think in the very northern and north western parts of Australia the MAX amount of Sun hours acheivable is actually 8 or 9.  For the majority of Australia the Max Sun hours is around 5 hours, perhaps 6.  In the southern parts of Tassie its actually as low as 2 or 3 hours & we are talking about clear days, not rainy ones.

Theres a chart, I will try to put a link for you shortly, but in short, if you had say 3 x 135 watt panels, which can produce roughly 7.6amps each per sun hour then perhaps in parts of NSW you might be able to produce roughly 120-140 amp hours per day, but in the lower part of tassie you might only be able to produce 70 amp hours.  If you need 100 amp hours a day, then your system isnt going to cut the mustard in Tassie, yet you will get by in other places.   

*  PLEASE NOTE, my figures wernt actually calculated properly but only to give you an idea.  Many people think sun hours are when the suns up, but thats not the case - chart to follow.

 

regards

jack

actually, that was the wrong chart I linked to, cant seem to find the other one.....

-- Edited by jack biggles on Thursday 28th of April 2011 06:29:18 PM

heres one, but it wasnt the original one i was thinking of. But you can go down the page & look up roughly where you are in Australia, then look at the corrosponding month to see what the Sun hours are for that location at that time (on a clear day).

http://aussiervproducts.com.au/webcontent4.htm

Hi smokeydk,

How long have you been using your system & what type of deep cycle battery do you have, ie: wet/agm/gel?

You seem to have very light power requirements as basic lights and water pump don't use much.

Do you use the waeco 40lt all the time or just some times?

The beauty of the 3way main fridge is it isnt relying on solar, its a different kettle of fish for those with compressor fridges.

 

Yes, smokey, I already have that spreadsheet, its a real good one.

I can see why your system works & yes there are very different system requirements for people on the casual weekender approach to the full time living ones.

I previously had a portable panel, AGM battery system set-up, not unlike yours, ACTUALLY, since I still have a the portable panel I decided to incorporate that into my new system, its like a freeby price wise to my new set up & like you I will keep that panel as a portable one. I then have further panels fitted to the roof of the new van......that way, either in poor conditions or where Im chasing extra power I can crack out the portable panel & chase the rays. I've long forgotten about the purchase cost of it.

I'm stepping into the unknown because after the van arrives I will be full timing for the first time & although I don't watch the telly much I can be power hungry in other ways. I also dislike caravan parks and only use them when I have to, so I had to think of everything.

My old system with the AGM battery worked really well & once again I have gone AGM batteries.