Fitting photovoltaic panels on a vehicle. Avoid The Solar-Wattage Trap

there is more BS printed about solar
panels and how they work and how to wire them up and how to make them efficient
written on the internet than probably any other subject certainly that I've
ever seen said this video is about from somebody who has been working on the
ground with solar panels for over thirty years where they when they work what
you're actually buying what you're getting for your money and when mounting
them on a vehicle or any platform boat doesn't matter any platform that is
regularly moving where to mount them on the vehicle if at all I'm Andrew st. Pierre White join me as I share my passion for building four-wheel drive
trucks and traveling to the remotest parts of the world okay first thing when mounting it
on a vehicle where do you mount it as you can see now got a panel on my roof
cool 819 what that is the claimed wattage of the manufacturer I'll get
more to that later 91 when I arrived last night there was a wind blowing and
so I faced the vehicle into the wind so I would have a more comfortable night
but as you can see rises in the East I'm pointing more Canada I'm getting nothing
in fact let's have a look to see how much current I'm actually getting point
one of an amp how much do you think I would get if the vehicle was pointed
towards the Sun considerably more so now I have to move the car well and that's
the problem and I feel like moving the car here is that same panel that I have
on the roof of my car and if I plug it into my extension let's see how much
can't I get if I edit point six of an amp can we improve that
yes what do you think now 3.1 amp light striking of photovoltaic cell or
Bleakley is very inefficient because of refraction that light not being absorbed
but being but bouncing off it and you can see like well enormous difference
between it angle correctly and not angle correctly an amorphous panels generally
are a little better at oblique light lower lower light levels than other
panels these are not I'm all for spells so what's the solution well at the
moment you have to have a stiff panel that you can tilt and point towards the
Sun but I don't want to take carry that in the car all the time it's a pain I
could slide it in and have it removable that's a better idea it's a
better idea to have that panel removable then nailed down if I was camped here
staying here for a while our and dependent upon the current that
the panel is producing I would have to move the vehicle and to get maximum
efficiency I would have to move it at least twice if not three times during
the day so maybe the solution is a solar blanket
now I that's a 90 watt panel that's a 90 watt panel there's a this is a hundred
and ninety watt solar blanket I decided that I'm going to carry a solar blanket
and Mars will carry a big one so let's have a look and see how this
one does all right real life okay unplug this one and I'm gonna plug in then red ox and a blanket well it's a
problem already so you can see that problem the problem is that it's flat well let's have a look and see what
current we're getting out of it anyway not even 1.2 amp it's the same problem
you have to be able to move them around to get them into the optimum position
for the Sun which means well it's not as easy as it might seem so we need to tilt
this to our Sun now good solar blankets have got eyes on them like this this
one's got a nice patch of eyes and can you see the problem don't do what I just did
buy yourself a solar blanket and then don't actually figure out how you're
going to actually mount it have things hung on the vehicle I'd like a nice sit
down now but I can't because I'm charging my batteries but now with it
pointed in the right direction and of course whatever you do you have to make
it easy to move because like you would have to move the vehicle three or four
times a day you would want to move the blanket three or four or five or six
times a day to get maximum amount of current back into your battery three
point seven or so amps from a hundred and ninety watt panel I was getting
about the same slightly less from a 90 watt semi-rigid panel so here's the
thing solar blankets and this is a general rule because of the fact that
they are indestructible and flexible and extremely compact they are not as
efficient in lower light levels than rigid panels solid rigid framed panels
that one puts on one's house are far more efficient than both of this these
types but when we're traveling we need something that's robust those panels are
not robust they're not designed to move I actually had one fitted to my first
troop carrier it was a hundred and 80 watt high voltage an amorphous panel and
that thing used to pump current it was absolutely magnificent but it suffered
exactly the same problems as the one that I've got on now which is reasonably
efficient but it's attached to an in or three ton truck that I have to move
every time the Sun decides to move which is quite often let's have a look at some
realism here that is a hundred and ninety watt panel
and in the book it tells me that the maximum power counter can deliver is
eleven point six amps the eleven point six amps measurement is the actual
tested maximum for that panel but the wattage isn't the wattage is a
theoretical wattage in other words if this panel was lying on the surface of
the Sun and there was no voltage drop in the cable going all the way to earth
then it would in theory produce a hundred and ninety watts so if I
calculate what hundred and ninety watts is in terms of actual amps it should be
able to produce fifteen point eight amps but it says in the book it can only
produce eleven point six amps that's because it's made of material that
reflects the Sun there's a voltage drop in the circuitry and the thing as it
gets warmer so the voltage drop increases because there's more
resistance in the cable you've got other cables going to the car and every time
there's a connection there's a voltage drop and so the theoretical maximum if
you've got your setup really good like I've got in here a proper solar charger
a power point tracker charger not a regulator okay more about that later a
power point tracker will look after the battery and it will look after the panel
which you can see now it's now fallen down okay so with all of that in mind
this panel will produce eleven point six amps on extremely bright day which is
nice healthy amount of current for my purposes ample those two panels they're
the one that'll work the best when the Sun is at its highest and brightest no
question the solar blanket will work better because it has a higher output
rating so in low light and amorphous and rigid panels are better in maximum light
solar blankets are better because could move them around so when you're
considering buying panels it's not really any point in looking at the
wattage because the wattage is a theoretical with a high quality
expensive panel the wattage is going to be closer to the actual than for in it
very inexpensive panels so if you see oh look a 250 watt panel for $300 Wow
but the 230 watts is a theoretical it's got nothing to do with what they
actually produce because what you're buying is not wattage say what it says
on the box but it's how much wattage is delivered to the battery I see it time
and time again somebody will come to me and say wow amazing and I think that's
not amazing you've been misled folks so how do you know how do you know if
you're getting good or bad do you know there's no real way to tell you go to a
good brand just go to a good brand and pay money a brief word about cables and
extensions for solar power I have seen many times a soda experts they'll come
into your home and say well so you're going to produce 10 amps don't need a
thick cable they're wrong they're absolutely fundamentally wrong because
and I'm sure there's a scientific reason for it and I don't know what that reason
is but of photovoltaic cells are incredibly sensitive to voltage drop
remarkably so so this panel here cannot deliver more than 11 or so amps and yet
I've got a cable that I made up this myself
and of course Anderson plugs or similar big heavy chunky cables Anderson's are
great but they're not good for permanent outside installations because they
they're not waterproof and they do corrode but for my our applications
where things have generally kept clean and dry they're absolutely fine and
ideal because they can carry a good current that cable I have there could
easily handle 60 to 80 amp over the 4 meter length it makes an enormous
difference and it's a strange thing and I don't haven't found anywhere where it
can be explained but for example go into your store where they sell the the red
arc blankets and go and have a look at the radar cables they're thicker than
this because they know they understand that voltage drop on cables is
significant in the loss in the combined losses that
happen when connecting photovoltaic cells so to summarize if you're going to
fit a panel to your vehicle and you want to make it a permanent installation on
your vehicle make them as big as you possibly can and do not angle them
actually have them flat because you'll get the most of the arc of the Sun now
typically with this angle pointing in the wrong direction I won't get any Sun
until probably new you have to compensate for the fact that it's not
going to be well positioned most of the time the just one up there for my
vehicle is not nearly enough but the one on the ground there either one of those
is because I can move it around ok secondly if you're going to use
extension cables and everything for your solar panels and make them big
at and chunky and don't skimp on the size of the cable and use really good
solid high amperage connectors and lastly this solar panel cheap is so
costly it's it is so obvious if you've got a small budget buy a high-quality
small panel do not think you're getting more current out of a cheaper nasty just
because it says a big figure wattage on the box I hope that's been helpful thank
you for watching

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