Solar The Solar Panel Thread

Crusty181

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Feb 7, 2010
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Thanks heaps for your reply @Macca_75
I am a bit worried about shade hitting the rooftop panels and making them basically redundant. I'm also a bit worried about having to clean the panels regularly as I don't carry a ladder with me so access is a bit tricky.

You reckon if I get 2 x panels on the roof and a decent regulator then I won't have to worry about that? I do have a portable blanket that could supplement it if needed.

I do like the idea of not having to lug around another portable panel and constantly stress about chasing the Sun with it.
We traveled around the country for over a year with only the single factory 150w fixed caravan panel and Topray pwn reg, and a 100w blanket for the Engel in the car. We had a generator, a lithium jump starter, and we also had the optimal partnership of a 120ah agm connected to a 100ah gel. We didnt have a dual battery in the car either, and I dont recall ever cleaning the vans fixed panel. Back then clearly we had not a single clue about solar, batteries, life, emotional distress, that fungus on my partners foot, nor what the hell my son did all day of the damn iPad. We were and still are sooper dooper power hungry pigs, everyone had multiple devices for no real reason and no-one ever has the foresight to charge any of them while we were driving. My son was homeschooled on a laptop and we love tv so the satellite stb was on constantly. We had virtually no issues at all and the measly 2 or 3 times we flattened the car battery was always my fault because of laziness, and it was always the car and the Engel, the van was always fine (as far as we knew, because mostly everything kept working). We used the generator a handful of times; remote Xbox challenges, and once when I was lazy with the 100w blanket and my Battery World mate who insisted that the lithium jump starter would hold a charge for 12 months ... he could not have been more wrong. Out of interest that 120ah agm from back then is still kicking around, is now 12 years old and was load tested at 90% last year.

Funny twist and tips for the uninitiated with lithium jump starters. Don't ever listen to your Battery World mates charge holding advice, and disconnect your caravan. Modern climate controls are electronic, are unresponsive with the ignition is off and remember their last setting. When you turn the car on the climate system will resume its last setting, and with the van connected when you turn that ignition key to jump start the car a portion of the avaibable energy from the jump starter is gobbled up elsewhere. A little aircon thanks, and little fridge cooling thanks, but not much car starting and in our case that was enough to render the jump starter useless. We now have the benefit of a retro LC70 with hands on cable slide controls and click turn manual knobs. I still cant break the habit of always turning off the climate control even though it doesnt matter for me in the current car.

Over the years Ive absorbed the incredible knowledge of many folk, in particular, @Boots in Action and @mikerezny (pssst, keep it to yourself but I do sometimes price checked them elsewhere :o). Ive done a bit (read a lot) of reading so like any true red blooded male Im now way overcompensating and things have now morphed into a completely different power world for us, but once upon a time with no clue, in a less efficient time, and with very little we were blindly successful and managed to survive on a fraction of what we have now.

For what its worth I found the Kings 200w blanket good enough to buy a second one
 
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Boots in Action

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Thanks @Drover that all makes sense. I have to make a decision in the next few days as I'm finally hitting Cairns which is the last big town that I will see for a while. At this stage I only need to last about a week off grid.

I have an Anderson plug that goes straight from the battery to my draw bar. I plug this into the car when driving and plug my portable solar blanket into it when stationary. I don't have a DC/DC charger and probably won't invest in one.
Does plugging it into the car when driving do anything/do much?
If I get a solar controller do I have that Anderson plug connected into it and then stop plugging it into my car while driving? Or do I need another Anderson plug on the draw bar?

I do have another Anderson plug on the awning side which I sometimes use for the solar blanket or plugging in the fridge.

Also, has anyone noticed that it's more difficult to lift/drop the roof with panels on top? As we are full time on the road the roof gets a fair work out.

At this stage I'm looking at:

A recycled roof top panel
A victron 100/30 mppt controller with Bluetooth (I do have a visual battery monitor already installed so I can track voltage, just a cheapo one)

Then just use my current blanket and potentially add another portable panel depending on how it all goes.
Hi @BunchOfHunts , well you are really getting a lot of answers from a lot of members, so now have lots of choices too. As far as charging van battery from car whilst driving, there are lots of posts on that too. And a lot depends on how connected and through what is already there. But basically, with modern cars and their desire to reduce fuel consumption, modern alternators do NOT charge up auxiliary batteries very well, if at all. Some more reading for you and more decisions to make.
 

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BunchOfHunts

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Hi @BunchOfHunts , well you are really getting a lot of answers from a lot of members, so now have lots of choices too. As far as charging van battery from car whilst driving, there are lots of posts on that too. And a lot depends on how connected and through what is already there. But basically, with modern cars and their desire to reduce fuel consumption, modern alternators do NOT charge up auxiliary batteries very well, if at all. Some more reading for you and more decisions to make.

I do have the modern smart alternator in an Everest. I don't really care about charging from my car just wondering if I need to keep using the Anderson connection plugged into my car. Does it help with running the fridge while driving, or putting less pressure on the 12 pin? If it doesn't really do anything then I'll just get it connected straight into the solar connector so I can use it for my blanket. If it does help somehow then I'll get another Anderson point put in for the solar.
 

Boots in Action

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I do have the modern smart alternator in an Everest. I don't really care about charging from my car just wondering if I need to keep using the Anderson connection plugged into my car. Does it help with running the fridge while driving, or putting less pressure on the 12 pin? If it doesn't really do anything then I'll just get it connected straight into the solar connector so I can use it for my blanket. If it does help somehow then I'll get another Anderson point put in for the solar.

@BunchOfHunts , plugging in the 12 pin plug to van is vital to keep the 3 way fridge in van going as it depends on amperage to keep fridge element operating - voltage not critical as long as above 11.7 volts and below 15.0 volts. So keep line to fridge connected. Voltage to properly charge your van battery is a different story as alternator voltage at van battery MUST be higher than van battery for ANY charging to occur. If battery is low enough, say down to 12 volts or lower, and alternator charging voltage is anywhere above this, then you will get some charging but not enough to properly bring battery up to useful levels. And remember, constant undercharging is detrimental to battery life and reduces storage capacity over time.
If connecting external solar panels, you are better to have an external Anderson plug on side of van with wiring direct to battery terminals (fused of course) although this may cause some conflict with the existing controller for your roof top panel. Better, if you can bypass the controller on external panel, and wire directly to the Solar INPut terminals on existing controller provided it has the capacity to handle the extra current. And another little point brought up by @mikerezny , that heat on panels decreases output, so not a good idea to place solar blanket over hot metal body parts on vehicle or even flat on ground - needs air gap/air flow. Not always possible, but something to think about if really wanting every bit of charge you can get.
 
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Drover

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Again it depends on set up as to charging from tug, panels on the roof mean you really don't need to and with a smart alternator the money spent on a DC-DC charger is better spent on the van.................. Using an Anderson plug for power from tug direct to fridge is the best way to keep your fridge going while driving, its reliable, fitting a fridge switch or a relay to cut power when stopped saves you remembering to pull the plug to save your start battery dying... I do a walk around check and pulling the plug is part of it, get out of vehicle walk around the rig, always, everytime its a must no matter how much I'm busting to go..... these checks means you see things before they fall off or some alarm goes when its too late.......................
Why I say panels on the roof is by the time I pack up and drive off my batteries are usually charged up and driving down the road is just keeping them that way............... I honestly don't think the kings is as bad as some make out they do have a good return policy which can be accessed around the country and the price is way less than some of the big name branded stuff which doesn't seem to last any longer.....
Trying to do it whilst on the road can be a pain unless you access to some sort of shed or work area, I have done mods to mine beside a creek, genny and soldering iron humming away but would have been happier in my shed......which ever way you go do it so that any future upgrades as in more panels or storage can be added without dismantling everything, so a good bit of thought is required........ rest assured you will want to add more storage which does mean more sun suckers..........

My set up has a Foxtel Box drawing power all day long, a couple of alarms, the fridge brain box (my fridge needs a 12v supply for its brain to work but runs on gas) and more often than not a phone/tablet will be plugged in, provision for the Engel to plug in if needed, a set up that means I don't have a panic attack about power and the next mod will be when these mongrel GEL's croak they will be replaced by a couple of 135ah AGM's a bit more storage and the ability to plug the Jeep in as well if it's starter battery needs a bit of a charge, I have an anderson outside van which I can plug a HD extension into for running stuff........
Its all made to "Plug an Play " style so no ginning around while away with bits and pieces..... KiSS is the main principle, too complicated gets to be a downer when travelling, my van set up in around 20 mins then I'm sitting back with a beer, sat dish set up, portable panel plugged in and awning locked down........ later on I may fiddle around with a few things but power isn't one of them.
 

mikerezny

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Hi,
what do you mean by a "recycled" roof top panel?

If you mean recycled from a domestic rooftop, beware that they are NOT 12V panels as used in camping. They are 24V panels and deliver around 40V. They are NOT suitable for use with PWM controllers or the cheap MPPT controllers that are just rebadged PWM controllers.
To utilised these panels you must have a real MPPT controller that is able to efficiently convert 40V down for use with 12V batteries.

The Victron MPPT controller you have in mind or equivalent is a must if you are intending to use domestic panels.

In the case pf PWM or rebadged PWM controllers, the panel voltage will exceed the maximum input voltage. Even if it doesn't, you will get less than 50% efficiency when using a 24V panel with these controllers.

If in doubt, post a photo or a link showing the specs of the panels you are considering.

take care
Mike
 
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Boots in Action

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Hi,
what do you mean by a "recycled" roof top panel?

If you mean recycled from a domestic rooftop, beware that they are NOT 12V panels as used in camping. They are 24V panels and deliver around 40V. They are NOT suitable for use with PWM controllers or the cheap MPPT controllers that are just rebadged PWM controllers.
To utilised these panels you must have a real MPPT controller that is able to efficiently convert 40V down for use with 12V batteries.

The Victron MPPT controller you have in mind or equivalent is a must if you are intending to use domestic panels.

In the case pf PWM or rebadged PWM controllers, the panel voltage will exceed the maximum input voltage. Even if it doesn't, you will get less than 50% efficiency when using a 24V panel with these controllers.

If in doubt, post a photo or a link showing the specs of the panels you are considering.

take care
Mike
Good point Mike @mikerezny . When I was getting roof top panels on my residence, I think I remember them being around 37 volts while operating. That is more than enough to FRY any 12 volt controller UNLESS it is a proper MPPT type.
 

mikerezny

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Thanks heaps for the warning @mikerezny
I am looking at a recycled house panel as you suggest (or maybe 2) and would only use them professionally installed and with the victron regulator.
Hi,
if you are considering two of these panels, you need to be very careful. Search through the threads on this site relating to connecting panels in series or in parallel, as well as the purpose of blocking and bypass diodes. This is well outside the knowledge base of many of those who might term themselves "professional" installers for caravan systems. If in any doubt, stick to one roof mounted panel. OR, consult @Crusty181 who has gone down this path.

take care
Mike
 
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Drover

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I have one for my shed its 250w and in theory will supply about 5amp on a good day, my caravan 200w panel in theory will supply nearly 11amps and the house one is bigger....... If I could find my notes I would have the exact data but I don't but pretty close...... of course how close they get to that is anyones guess.......
I would stick with a 12v caravan panel, you will have more versatility for adding to the system, plugging i a portable etc, go the house panel route and thats it where you stay..........
Why do caravans have less panels than a house to provide the same output, that is the question..........
 

mikerezny

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Hi,
just so we are all on the same page, here is a basic tutorial on electronics:

CURRENT (I), VOLTAGE (V), and POWER (W)

and the following formula:

POWER = VOLTAGE x CURRENT, or algebraically W = V x I.

Armed with that knowledge:

House panels and 12V panels both provide about the same POWER output per sq m. House panels deliver this power at a voltage of around 40V, 12V panels deliver the same power but at around 20V.

House panels will deliver the same POWER as 12V panels BUT at TWICE the VOLTAGE and HALF the CURRENT compared to a 12V panel.
So, a 200W house panel will deliver 200W: 5A at 40V, a similar sized 12V panel will deliver 10A at 20V.

I don't believe I can be any clearer.

take care
Mike
 
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mikerezny

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So the MPPT controller can convert the 5a into 10a but a PVM can't?
Absolutely correct.

A PWM (Pulse Width Modulation) controller just chops the current at a fast rate so that the output voltage is maintained at a determined level.
Thus, a PWM controller can NEVER supply more current that the panel can produce.

A MPPT controller is basically a DC to DC convertor.
So the POWER out of the controller is equal to the POWER into the controller LESS the inefficiency of the conversion, typically 5-10%.
Further, it loads the solar panel so it is run at its maximum power point.

Thus, a MPPT controller can extract the rated power from a solar panel when it is optimally aligned and the available sunshine is the same as when the panel was rated (1,000W per sq m) and the panel temperature is 25C.

So, a 200W panel connected to an MPPT controller can deliver about 185W (assuming 92.5% efficiency) to a battery. If the charge voltage is, say 14.4V, that will be 12.85A.

I hope that this makes sense.

Mike
 
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Macca_75

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Thanks heaps for your reply @Macca_75
I am a bit worried about shade hitting the rooftop panels and making them basically redundant. I'm also a bit worried about having to clean the panels regularly as I don't carry a ladder with me so access is a bit tricky.

You reckon if I get 2 x panels on the roof and a decent regulator then I won't have to worry about that? I do have a portable blanket that could supplement it if needed.

I do like the idea of not having to lug around another portable panel and constantly stress about chasing the Sun with it.
I'm finding it hard to follow the threads (thats me, not the threads).

If I was spending a lot of time free camping I would definitely look into permanent panels over having to get one out every day, etc.

The Victron gear is great and bullet proof (not cheap) - think of it as the Rolls Royce of gear, as for PVM vs MPPT you can expect anywhere from 0-30% gain from the same panels (for "12v panels"). You'll get a higher gain from house panels, but that's not a fair comparison.

The app for your phone to connect to Victron is sleek. Easy to understand.

It's important to understand if the current Andersons connect directly via the battery (hopefully they are fused and also attached to any shunt if you have one). If they connect to the battery your portable panel will need a regulator (PWM or MPPT) - there is a very good chance this second regulator will "fight" with your fixed one. Victron have a solution for this where you add a battery sense and create a virtual network with both batteries and the battery sense but this is getting more advanced.

If you can connect an Anderson directly into the MPPT controller you can attached a portable panel (assuming a very similar voltage) - no fighting between regulators. My suggestion around changing the color of the Anderson was grey/black share a key and are interchangeable. Red/Yellow/Blue/whatever are different and ONLY plug into the same color - this will avoid you "accidently" plugging in your unregulated panel direct to the battery (via your existing Andersons - bad things will happen if you do this!)

I have a 2013 Ford Ranger and it puts about 8A into the battery when driving (with no DC/DC). You need to understand how the Victron (or any other MPPT controller works) but the panels MAY also add their power into you batteries if they are flat enough while you drive. You may need to look if you need to get smart charge disabled on your Everest.
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