Solar Panels - Information and Questions

[Nightjar]

What was the advice ?
Was it to alter the original parallel connected panels to series connected panels ?

If that is the case , how would it help ?
Would it work better when lesser sunlight is available like on an intermittent cloudy day?

Yes, what I wrote above! They come wired parallel I wired them in series.
My apologies, the voltage doubles but amperage remains the same but more efficient through the MPPT.
Was going to correct mistake in post #27 but the edit button has disappeared.
***My tutor gave me a slapping. ***

 

[iamagoldenoldie2]

Bogger, the old battery chargers are still useful, the modern multi stage chargers read the battery condition then start to work but if the voltage is too low Iget the error message battery failure, so I hook the dead battery top to toehold charger switch it on and not much happens, its pumping about 1 amp into the dead battery, then something miraculous happens after 3 hours its pumping about 4 amps into the dead battery , it takes a while to kick start the charging process now with the little sealed lead acid batteries I used to hook up a 12volt bulb with a potentiometer in line and set charting at 1/2 amp that way I didn't cook the battery I have some old very very heavy sealed lead acid batteries yashyua brand ex telecom 6 volters 110 amp hour they were 7.6 volt 6 years ago stored and forgotten tested voltage 3.1 so my charging technique has brought them back to 5.8 volts good for my led lights there is a wealth if information in the forum you just need to look at the suggestions old 12 volters were charged at 13 .5 volts newer batteries need about 14.5 volts and lithium iron a tad more so don't throw the older charges away,,, parallel and series wiring is another mind bender

 

[ChrisM]

Thanks for all the comments so far everyone. Im slowly getting my head around this series v parallel caper [well sorta,kinda]. This morning I went out and got a new multimeter capable of reading amps. AND a quick thank you to the guy who overheard my confused explanation about what I was trying to do and explained to me step by step on how to set up and read the Amp output. So I set it up first thing this morning and now waiting for the sun to hit the panels this arvo.
Im going to try everybodys patience one more time and see if we can work out a project specific result.
OK. What is the purpose of these solar panels, why do I think i need them and what will they be maintaining. AND.....yes my cute little midget twister board panels are getting scrapped. The ones that Wally69 suggested are very close to the size that can fit in the existing housing.
The receiver is a Century N70T 100Ah Deep Cycle currently hooked to the start battery Century N70ZZX 810CCA through some sort of smart switch, so its being topped up while the car is running. From the Deep Cycle side I will be using power for LED lights, detector batteries ,an inverter {possibly 1000W} phone and laptop ...and whatever other smaller units that need charging.
In my simple reasoning the demand on the battery is not great because its not a constant demand but running it flat is not a healthy thing......so enter the solar panels as a Top Up.
The car can be parked for 2 or 3 days without being moved and with the only load being the 80L Kings fridge {in most cases}.
The panels are mounted permanently to the front of the roof rack {not Ideal I know} but it saves the need to carry larger panels for short trips and doesnt take up valuable space

.
So....after this long winded explanation i need to know if using 2 new replacement {1.2A] panels will have a reasonable ability to top up the deep cycle over a period of time.
As confused as I sound about this {which I am} In a nut shell is the power generated going to be worth the effort of setting it up?
Cheers
ChrisM

 

[Jaros]

Probably not mate. But think what you have learned during this exercise. Modern panels are so much more capable and lightweight as well.

 

[moeee]

What is that Coffin looking thing in your pictures ?
How come in the first 2 pictures it is a shiny black colour and in the 3rd picture it is dirty white colour ?

 

[Occasional_panner]

I wouldn't bother with those, just toss them and start again.

Something to consider is that you'll need to park in the sun and probably move the vehicle many times to chase the sun.
Usually a pain considering where you are and terrain/trees.

Most situations these days to top up a battery that runs a fridge and lights etc needs 140-160 watts minimum, so you're way short on power with those.

PWM (pulse width modulation) controllers just connect the panel direct to the battery, as the battery voltage rises they cut in and out with the feed so not to overcharge the battery.

MPPT (multi point power tracking) uses a dc dc converter and brings in the full voltage and converts that to the charge voltage, this is more efficient, but only worth while when you are talking of a reasonable size system, I personally wouldn't bother unless you are running 250w +
The other advantage of mppt is you can run a 24v panel, which in fact has a maximum amperage at around 30v, open circuit of around 35, feeding a higher voltage through a line 20-30m away isn't such a big deal then, you won't get anywhere near the voltage drop through the line. The incoming voltage to the regulator will be converted close to the battery to 12 v and losses will be minimal compared to running the same length cable with a 12v panel and a pwm controller.

Even better run two or three 24v panels in series through an mppt, then line losses would be .5-1%
This chart helps as a reference.

 

[Occasional_panner]

A 12 volt battery is pretty much a 12 Volt battery.

Picture a 5 gallon bucket and a 44 gallon drum , each full of water with a tap on 'em.
They only pour out water the same , depending on how far you open the tap.

You also need to consider the discharge rate, or C rating, some can handle feeding 100amps an hour, other far less or far more, get this wrong and you'll stuff your batteries in one trip.

 

[Jaros]

O.P. that formula wheel is always handy to have around. I have one on my Radio room wall as well as the frequency charts for all Hamm bands and 80 UHF channels as one of my 2way handheld radios is calibrated in frequencies only.

 

[moeee]

A 12 volt battery is pretty much a 12 Volt battery.

Picture a 5 gallon bucket and a 44 gallon drum , each full of water with a tap on 'em.
They only pour out water the same , depending on how far you open the tap.

You also need to consider the discharge rate, or C rating, some can handle feeding 100amps an hour, other far less or far more, get this wrong and you'll stuff your batteries in one trip.

The guy was getting overwhelmed with the information presented and wanted it in simple layman terms

 

[user 7268]

through some sort of smart switch
Simply .................. what is this switch ? If it's simply an isolator then you would be best to swap it out with a unit like a Projecta idc25 which has an MPPT controller built in and will also allow your alternator to fully charge you battery. If you only have an isolator fitted then your vehicle alternator will NEVER fully charge a deep cycle as it just doesn't put out enough voltage to do so. Probably around 80% at best. By fitting a DC DC controller at least you can utilise your deep cycle battery to its max plus also add some fold out solar panels later to the system if you wish ? You would probably struggle for a 100 amp battery to supply power for 3 days to an 80 litre, but many things come into effect regards this. Outside temps, how often the fridge is opened and closed, how full it is etc etc
Also if you fridge has a high and low cut out option select high otherwise it will probably take battery (deep cycle) below recommended discharge level and eventually damage it.

Just a footnote regards Projecta IDC25 ................ they list power in as 9 volt to 32 volt input BUT only 23 volt solar input

 

[Occasional_panner]

A 12 volt battery is pretty much a 12 Volt battery.

Picture a 5 gallon bucket and a 44 gallon drum , each full of water with a tap on 'em.
They only pour out water the same , depending on how far you open the tap.

You also need to consider the discharge rate, or C rating, some can handle feeding 100amps an hour, other far less or far more, get this wrong and you'll stuff your batteries in one trip.

The guy was getting overwhelmed with the information presented and wanted it in simple layman terms

Ohh jeez don't get all sooky, just trying to give correct info that may save someone some big dollars.

Dunno why I bother sometimes.

 

[Occasional_panner]

Bogger, I have the best bloody redarc in mine and the rotten thing can't handle a 24v panel, bloody hopeless design all the vehicle based systems.

 

[user 7268]

Bogger, I have the best bloody redarc in mine and the rotten thing can't handle a 24v panel, bloody hopeless design all the vehicle based systems.

OP funny you should say that as went looking for Redarc specs the other day regards solar input and couldn't find what they rated the unit at ? The price of the Redarc over the Projecta unit ............. it should handle a 100 volts solar

 

[ChrisM]

Firstly I need to say thank you to all you guys for your invaluable input. Thats what makes this forum such an amazing pool of information and opinions. Its a huge learning curve for me when it comes to solar and its efficiency. No matter how I dice it or slice it, the current real estate Im allocating for solar just wont work. It may have worked 20 years ago to some degree but the demand we put on solar today with all the gizmos we have or need just doesnt cut the mustard [from what Ive learned over the last week or so} so once again, thank you to everyone.
Im now the proud owner of a set of 160W folding solar panels to help me start off my solar journey and education...lol. Now I can get on with winching the damn roof rack back onto the roof and finish setting up the vehicle for next years big trip.
Bogger and O.P thanks for your last few comments, you both hit the nail on the head. It cemented the fact that im flogging a dead horse.
Ive attached a pic of the smart switch under the bonnet that I believe links the batteries together.

Once I get all the electrics fitted and sorted Ill get the Lekky to hook em all up.
Cheers
ChrisM

 

[moeee]

just trying to give correct info that may save someone some big dollars.

Yup - me too

 

[user 7268]

Chris from what I can gather it's only an isolator you have currently fitted. Best bet would be to fit a Projecta IDC25 ............... around $250 it's as good as you will get for the money. That way your vehicle altenator can charge deep cycle fully when running and also enables you to get the most from your panels with the MPPT controller. The controller you get with panels will be a real cheapy, and even if marked MPPT will probably only be a PWM type. It's a few dollars to set the system up properly but once done will give you years of service and at the end of the day you only need to destroy one deep cycle battery and it's more than a good controller. :Y:

 

[Occasional_panner]

VSR's can be kind of allright IF your alternator is upto the task, flooded lead acids work better with them, sealed agm's probably asking for trouble.
Modern vehicles will only provide an insufficient voltage to fully charge the secondary.
Even if the alternator is providing a sufficient supply, quite often peoples cheapness has seen them fit a substandard cable which has far too much voltage drop and from that alone the secondary doesn't get a decent charge.
First, test the voltage of your secondary when the VSR has fed it's supply till it peaks out.
That voltage needs to be matched to the specs of YOUR battery.... look it up, they are all different.

The problem with VSR's is they are horribly harsh with a battery compared to a dc dc charger with proper charging algorithms.
Basically all it's going to do is connect the alternator to your secondary, it's just a relay.
How your alternator handles the charge will depend on how your battery fares, flooded LA's cop a hell of a lot more punishment charge wise, but don't like corrugations in roads.
A dc dc charger will feed the correct amps (not too much too quick) and lessen them off to take care of the battery, particularly SLA's
Fit the dc dc as close as you can to the secondary.

But if you only do two or three trips a year a vsr is fine, but you'll need to charge the secondary properly with a smart charger in your driveway at least every couple of weeks.(assuming the secondary is only used on trips)

That takes care of the vehicle charging

The solar panel charging is another story.
MPPT is and always will be better, for a small system like a 160w panel the efficiency difference is so small I personally wouldn't bother with mppt, as long as you set the charge parameters to match your battery (assuming your controller can do this) then you'll be fine, you basically need bulk, absorption, and float volts to take proper care of the battery.
If it's a really crap controller and doesn't show those volts, or allows adjustment, then toss it over the fence.

BTW don't forget if you do get a dc dc charger for the vehicle, most have a solar input which is mppt, so you can utilize that part of the controller for your solar, like Bogger said, be careful when matching a solar panel to one though as the upper voltage limits are usually only suited to 12v panels (12v panels will provide more than 12v though)

Sheesh, that's enough typing for a night.

 

[Gem in I]

I would also like to thank the valuable help given on this topic. Education is achieved in steps and myself and others also reading the topic are on different levels of this info and everyone's reply seems very professional at different steps :Y: :Y:
I kept the battery, it was fairly new and with the additional info i'm looking forward to charged equipment and cold beers :Y: :Y: arty:

 

[Nightjar]

I hear what everyone is saying about redarc etc etc to charge second battery, however.
Step back to the 80's and my MQ Patrol which helped me contract gold fever.
This Patrol had a 24V system so I fitted an extra 12V alternator to charge a third battery to run my Engel and charge detector batteries and the like.
Along came my GQ patrol to which I fitted an auxiliary battery separated with a simple solonoid. https://www.ebay.com.au/itm/12V-14V...+solonoids&_from=R40&rt=nc&_trksid=m570.l1313
Next my GU Patrol, once again fitted an auxiliary battery separated with above solonoid.
Later I fitted a third battery + solonoid separating 2nd & 3rd battery.
A roof mounted solar panel feeds this 3rd battery via PVM.
When we are parked up the third battery is independent (isolator open) from batteries 1 & 2 and a fold up solar wired in series is connected by anderson plug, feeds battery 3 via MPPT.
This may sound complicated but my "box of tricks" on the back of the ute has served me problem free for 15+ years.
The MPPT is hidden in this photo.

screen capture windows

 

[Gem in I]

And nobody has posted back to the future yet :lol:

great build nightjar.