solar panel research - daily amp useage

[Braveheart]

I'm looking at the possibility of going full-time with my wife, and am looking at fitting a solar panel, possibly a 200W.
I have done some rough calculations and I'm looking at getting through about 25 - 30 amps per day in WINTER.
I doubt I'll get through that much every day, but I'd rather over estimate than under estimate.
Does 25 - 30amps p/day seem realistic to those out there who have more experience ?

I have recently fitted LED lighting.

I use -:
EBERSPACHER AIRTRONIC D2 2.83 amps
CARVER cascade 2 (heated by gas) WATER HEATER 0.25 amps
LED fluorescent 8W X 2 0.67 amps each
Various LED @ 0.12 & 0.25 amps
Shurflo water pump ? 5.0 amps
AVTEX TV 4.5 amps
Status tv booster ? 0.08 or 1.0 amps

Previous to fitting LEDs I managed to wildcamp in Scotland in March this year for a month without ever going on a EHU. However, I did cover 2500 miles, which helped charge up my 1 X 125amp LB and watched TV/DVD for a total of 5hrs in that month.
I wouldn't be able to afford that much fuel if I was to full time. So my battery wouldn't get as much charge from my alternator. I have been picking my way through loads of posts in this forum and I'm starting to get an idea about solar but any advice would be welcome.

I'm looking at staying in the UK and possibly Europe. Thoughts....?

 

[Firefox]

Very tricky to estimate. It depends on latitude, panel angle and cloud cover over the winter.

I guess you could say on average 1/5 of panel capacity in winter and 1/3 in summer as conservative.

Say 40W in winter and 70W in summer, 3A and 5A, from a 200W panel.

I think you mean Amp hours rather than A. Winter you'd only get 6 hours of decent sun say 9 till 3 so that's 6Ax3h = 18Ah. You may be lucky and get near 25Ah with bit of sun at dawn and dusk. I'm thinking 25-30Ah would be on the high side though.

In summer 5A over 10 hours of decent sun should see 60Ah to 70Ah total with some more lower charging at dawn and dusk.

 

[Braveheart]

Thanks Firefox,
Yes I meant Amp hours.
I have been generous in my usage allowing for 2 hrs of TV even though I don't watch that much and its one of the highest draws on the battery.
The highest being the Airtronic heater.

I have read a lot of your posts (and your excellent fitting guide) regarding solar. I notice that you have said roughly a 110amp battery per 100watt panel.
Would I still need 2 batteries if I'm going to produce only about 18amps on a sunny day using one 200W panel?

Also, can I wire a solar panel through a zig marque III or do I have to connect directly to the battery (via a regulator in both cases of course) ?

Sorry if this sounds dumb. I have grasped how you have explained it in your video and your posts, but I'm just wondering if I can send the power via the Zig?

 

[Firefox]

Two batteries will still be useful. Because in the winter there will be periods when you may not produce enough so your batteries will give you more reserves over that time. You may still need the odd hook up or alternator charge if it is very poor weather. And in Spring, Summer, Autumn the two batteries will take advantage of the extra charge available which should make you completely self sufficient

 

[oldtech]

Hi Braveheart

I am in a similar situation to yourself.
I spent literally months reading up on solar power for full-timing
and eventually found this :-

HandyBob's Blog

I wish I'd found it first !
This guy REALLY knows the subject inside and out and he is certainly not
a fan of the so-called "professionals" in the solar business.

It's a lot to read , I admit , but worth every minute spent ,especially the parts
about why people who buy solar systems are so often disappointed.
This page should be particularly useful to you :-

The RV Battery Charging Puzzle « HandyBob's Blog

It's an American website so some of the terms used are different to the ones we use in the UK
e.g. what we call wild-camping , they seem to call "boondocking".

Anyway I'd recommend it to everyone with an interest in this subject.
It won't cost anything but time to read it ,and could save you hundreds of pounds
.... and a lot of frustration !

Good luck with the project ...
( but with Handy Bob's advice , you won't need luck )

Oldtech

 

[Braveheart]

Thank you Oldtech,
I have started to read this, it seems like an interesting and informative read, and can't wait to digest it all and get to the nitty gritty.
I really appreciate the link.:cheers:

 

[Firefox]

I liked the link; it contains some good info but you have to search through a lot of waffle for it! The guy has a background in sales as well as electronics and he does talk a bit like a salesman with lots of "red hot" recommendations for this or that piece of kit while continually telling you he is not selling anything! Also it is very American based with references to #4 wire etc. It would be more helpful if he had said 5mm2 wire or some more international description. Americans seem to live in their own bubble and assume anyone reading is from the US, even on the internet! I'm not totally sure his advice on shadows on panels is right or totally up to date. Many modern panels cope with shadows much better than the older versions.

 

[oldtech]

it is very American based with references to #4 wire etc. It would be more helpful if he had said 5mm2 wire or some more international description. Americans seem to live in their own bubble and assume anyone reading is from the US, .

Hi Firefox

I can't fault you on anything that you say .
I work in a very "techie" business , and usually for American companies ,and I agree about US tech terms
and the fact that they just don't understand that the rest of the world has moved on , and standardised
to the metric system .... it often makes my own work more difficult .

But having said that , conversion tables are easy to find ( just Google 'American Wire Gauge conversion' )
and HandyBob offers a goldmine of valuable info .... all in one place !
I've personally done a LOT of research on the products he recommends ,on more forums than I could count.
They may not be the cheapest , but you simply will not find ANYONE who doubts their quality.
And as he says , in many of his articles , he personally purchased , and then binned , many other products
that just did not perform as advertised , or even work at all !!

So he learned his trade the hard way , many times at his own expense !

Many years ago I lived and worked in Spain as an electronic engineer and often did work " on the side"
for a big solar power company ( who I won't name ! ).... mostly doing repairs to inverters that they had supplied
but couldn't fix .
I can personally assure people that nobody in the company had a clue what they were talking about !
And just as HandyBob says , their solution was always " buy more panels " , or "buy more batteries"

And if you want an alternative opinion , check out this one :-

RV Electrical

It is usually NOT the equipment that is at fault .
It's either the system specification that's wrong , or more often , the way it was installed and/or used.

But anyway , thanks for the comments ... always appreciated.

Best wishes

Oldtech

 

[Firefox]

Thanks for the other link - again very interesting.

The first thing that jumps out is his definition of a "small" system - under 350-400 watts! They do things big in the States! 300W to me would be a big system for the UK. There can't be many people running more than 3x100w panels and 3x100 Ah batteries here.

But generally his advice is very sound mirroring that of the other guy. 1W per Ah of battery, big enough wires, and the right batteries.

Interesting to see the recommendation of golf cart 6V or semi-traction batteries - how many people use those here? Also his advice not to discharge more than 25-50% is spot on.

Another telling figure is that the starter or marine type (leisure batteries or re-labeled starter battery as used in the UK) will only last 30-50 cycles if deep cycled. This accords with my experience. I am sure many UK motorhomers deep cycle their leisure/starter batteries and after 30 weekends, only 1/2 a years worth of use they start to fail. It's why you see many people on here with power problems and batteries only 1-2 years old. And a host more with 5 year old vans with the original batteries installed wondering why their electrics are not working properly.

 

[thegoodlookingbloke]

Do the calculations, then tear them up and then you can sit in your motorhome with a dimming LED cluster, thinking " I think I made a wise decision to spend all this money on solar power" then when the LED stops working and as you start your engine to get some life into you leisure battery, you will think "Oh Sh**"

Happy are the people that get excited about solar power, but sad are the ones that actually get it.:wave:

 

[maingate]

Do the calculations, then tear them up and then you can sit in your motorhome with a dimming LED cluster, thinking " I think I made a wise decision to spend all this money on solar power" then when the LED stops working and as you start your engine to get some life into you leisure battery, you will think "Oh Sh**"

Happy are the people that get excited about solar power, but sad are the ones that actually get it.:wave:

You seem to be be on your own on this one chum.

Do you belong to the Flat Earth Society or similar?

 

[vwalan]

i,m sat now with 240v fridge on inverter computer on inverter all from batteries powered by solar . it works if you have enough . and batteries . mind far better than led lights are gas lights . light heat and keeps midges away . but solar works . not so good in uk in winter but spain is calling . shant have ehu all winter . lovelly sunshine i hope .

 

[Firefox]

Just spent all summer on one 90W solar panel for all lighting and computer use ventilation fans and pumps etc.

I didn't plug in for 3 months and use the van every evening and sometimes in the day. Also my alternator charge is on a manual switch not a relay, so I never used that either, as I didn't need to. I guess some people may have different experiences, but either they got a duff panel or didn't fit it correctly :lol-053:

 

[vwalan]

as i have said before i power a fridge and a big freezer at home from the trailer .run a lead from the trailer into the house saves using mains and keeps everything working . i use 600amp of truck batteries and sometimes add another 200amp that work as 12v in the truck . keep the 24v system on the truck separate . works for me.

 

[thegoodlookingbloke]

You seem to be be on your own on this one chum.

Do you belong to the Flat Earth Society or similar?

I have been involved with solar panels from their onset, I have spent a long lifetime in Electronic design and I do know my onions when it comes to power, take it from me, the general public only see what's written on the box like:- 10Amps, "uprate your leisure battery", "loads of Ampere hours". "need a regulator for the massive power from the panels" etc etc. They dont give any details on efficiency, actual average daily power, the losses involved in the charging process, the losses of getting the power back out....I could go on forever.

If you live in Spain and have loads of good sunshine, lots of solar panels and batteries like VWALAN, then that's a different matter, he has got it sorted, but dream on with the others and enjoy your solar panels in the UK it is a great experience...Chum :wave:

Is the Earth flat by the way. ?:wave:

 

[maingate]

I have been involved with solar panels from their onset, I have spent a long lifetime in Electronic design and I do know my onions when it comes to power, take it from me, the general public only see what's written on the box like:- 10Amps, "uprate your leisure battery", "loads of Ampere hours". "need a regulator for the massive power from the panels" etc etc. They dont give any details on efficiency, actual average daily power, the losses involved in the charging process, the losses of getting the power back out....I could go on forever.

If you live in Spain and have loads of good sunshine, lots of solar panels and batteries like VWALAN, then that's a different matter, he has got it sorted, but dream on with the others and enjoy your solar panels in the UK it is a great experience...Chum :wave:

Is the Earth flat by the way. ?:wave:

What a load of bollocks. I bet you are not good looking either.



If you are so clever, why have you not designed better panels or more importantly, better regulators and 12 volt chargers.

How do you manage when wildcamping then? That is if you ever do.

Talk is cheap.

 

[thegoodlookingbloke]

What a load of bollocks. I bet you are not good looking either.



If you are so clever, why have you not designed better panels or more importantly, better regulators and 12 volt chargers.

How do you manage when wildcamping then? That is if you ever do.

Talk is cheap.

Why do you think the government doesn't lay fields of solar panels to feed into the national grid as they do in equatorial countries instead they use much more expensive wind turbines.

The clue is somewhere in there...see if you can work it out. :dance:

 

[maingate]

Why do you think the government doesn't lay fields of solar panels to feed into the national grid as they do in equatorial countries instead they use much more expensive wind turbines.

The clue is somewhere in there...see if you can work it out. :dance:

A couple of my neighbours have a roof full of solar panels. You work that one out.

BTW, I have a wind turbine myself ............ for when the Sun don't shine.

Now tell me about how much wildcamping you do. :idea:

 

[Jojo]

miaaow!

Hello boys!

Well. I'm neither an electrical engineer or a flat earther, and I don't do much wildcamping, only just started... but I've had to commit completely as it's now my only home. My lovely dad fitted 2 x 80W solar panels on the roof of my van before I set off to the frozen north where I wouldn't have lasted more than 3 days without them. The charging current is probably very low - we can't find an ammeter to fit into the circuit to tell me what they're doing (anyone know of something?) but they make a pop-pop noise when they're doing something and I can graph the battery charge over time to see what effect they're having. I have proof that (even in almost-winter in the north) they have allowed me to carry on with my life for at least 10 days longer than I would have been able to otherwise. Don't knock it.

I was running normal lights and a power-sucking hi-fi installed by previous owner, and a heater fan occasionally. Every night (5pm-9am) the batteries went down about 0.6V and every day they charged up by about 0.5V. It took about 10 days to go down overall from 12.7V to 11.7V, at which point the pump started behaving badly and complaining, so I needed to plug in somewhere. Couple of days later, when the sun was bright and the van tilted, the batteries reached maximum charge at 13.2V. You can't tell me that's worth nothing.

If you don't need to live off-grid then maybe panels aren't really worth the investment or trouble of installation. But if you do, they are.

I'm now in the process of changing over lights to LEDs and buying a portable radio ; ) I've already learned not to run the heater fan unless I'm on mains. I estimate this will mean the intervals between hook-ups will be more than 2 weeks, possibly longer (saving money and time - there's nowhere local or cheap) and in the summer may be completely unnecessary - as long as the batteries recover to full charge in the daytime, I'll be OK.

To have or not to have solar panels isn't a black/white problem, so taking definite positions is a bit daft. If you need solar panels and can make them work for your situation, fine. If you don't need them, why not live and let live? It doesn't help people to put them off what might work for them because it doesn't work for you.

 

[oldtech]

Here we go .... AGAIN !

Here we go .... AGAIN !

What started out as an intelligent , polite discussion amongst people wanting
to share their knowledge and experience of solar power has slid towards
an " I know best " type of scrap.... how tedious !

I wasn't going to comment , but what the hell ....

Speaking as " non-flat earther " , and from what I see in the other posts here ...
Myself , VWAlan , Firefox , JoJo ,and Braveheart ... and probably MANY others ....

do NOT want to be in campsite with hook-up
do NOT want to run a generator
do NOT want to waste fuel driving around just to charge the batteries
but WOULD like some electricity , especially at night.

TRUE it is not perfect and it is not exactly "free " energy , but it can work , and it is
green / renewable energy and it doesn't make any noise that might annoy others .
By sharing our experiences on here we all have a possibility of improving our systems
..... call me old-fashioned if you will .

I ,for one , am very thankful to have it available .
I will freely admit that it may not be cost effective in Winter or in Northern locations
.... but I'm not usually in those situations ,
.... and I'm thankful for that as well !

So , to all the people mentioned above , many thanks for your valuable input ( oops ..a pun ..sorry ! )
To anyone else ....
... just ....thanks.

Happy Solar harvesting to one and all

Oldtech