Solar panels, fixed to the roof, adjustable on the roof, or portable?
- Thread starter Fatboyz
- Start date
spikemd
Explorer
X2. I did a quick experiment in the fall and just holding a hand shadow over a 100watt flat panel dropped output 80%! In contrast, a hand shadow on a flexible panel (powerfilm, flexopwer) only dropped 20%.
I dont want to bake my truck in the sun for solar panels. Keep them mobile and store them up top if u dont have space inside.
Bear in NM
Adventurer
I was yaking with one of the guys over at my local solar center, as I was looking at panels for my "new" van. We were discussing shading, and I mentioned doing tests in the past with my portable panels. He noted something that I had not snapped to. Depending on how your panel is internally wired with the diodes, different locations on any given panel may give completely different results.
If this is true, then it might be a consideration on the roof, if you have items up there that might cast some shade, at some times. Maybe affect/consider panel orientation?
Craig
If this is true, then it might be a consideration on the roof, if you have items up there that might cast some shade, at some times. Maybe affect/consider panel orientation?
Craig
rayra
Expedition Leader
Absolutely so and is almost totally the reason for the differences. Nobody talks about it much because few are aware of it. Just as most disregard orientation.
/
finally got my wire-feed welder, I can get started soon on my roof bracket for my folding panel kit. Got a couple other things to finish first.
/
finally got my wire-feed welder, I can get started soon on my roof bracket for my folding panel kit. Got a couple other things to finish first.
Bear in NM
Adventurer
Rayra,
I feel like a dummy, as last summer I did some testing with 2 of my panels wired parallel and in series, and was testing shading effect. I concluded that for my two panels, that I was doing better parallel. Guess I need to retest that.
I had discounted roof mounting threads (other than general info), as I was not planning on going that route with my Av or cargo trailer. I have a new van, and I am back to revisiting roof racks, roof mount systems, etc. The van came with 3 contractor cross rails that are hell built for stout. I plan on keeping them, and looking into panel mounts, baskets etc. Thankfully I am in the SW and not Alberta, so tilting is not life or death, but I understand the efficiency side. I'll have to revist your thread.
Now how does one design a 4 way hing tilt system....;^)
Craig
I feel like a dummy, as last summer I did some testing with 2 of my panels wired parallel and in series, and was testing shading effect. I concluded that for my two panels, that I was doing better parallel. Guess I need to retest that.
I had discounted roof mounting threads (other than general info), as I was not planning on going that route with my Av or cargo trailer. I have a new van, and I am back to revisiting roof racks, roof mount systems, etc. The van came with 3 contractor cross rails that are hell built for stout. I plan on keeping them, and looking into panel mounts, baskets etc. Thankfully I am in the SW and not Alberta, so tilting is not life or death, but I understand the efficiency side. I'll have to revist your thread.
Now how does one design a 4 way hing tilt system....;^)
Craig
rayra
Expedition Leader
/ I think paralleling the panel connections would be best, not sure what you are meaning. The problem isn't so much how the whole panels are wired, but more how the individual cells in A panel are wired. But it's the same problem either way. In series arrangement, a failure or blockage of one unit interferes with the power flow from the rest. So you want a whole panel or whole array wholly in the sun. And if you want better fault tolerance, you have to find a panel whose internal cells are not all wired in one big series arrangement.
Two way mount is easy, you just use readily removable fasteners on two opposing sides. Disconnect the 'high' side and pivot the panel up and insert a stay / stanchion bar that's the right length to get the right panel angle for your latitude. Or use an adjustable bar and a simple aiming tube. The other axis would be up to your parking job.
I'm still planning to go with a TV wall mount with a wide range of adjustability, but first I'm re-working my panel kit to put it on a diet and reduce its overall height. I haven't started chopping anything down, yet.
Two way mount is easy, you just use readily removable fasteners on two opposing sides. Disconnect the 'high' side and pivot the panel up and insert a stay / stanchion bar that's the right length to get the right panel angle for your latitude. Or use an adjustable bar and a simple aiming tube. The other axis would be up to your parking job.
I'm still planning to go with a TV wall mount with a wide range of adjustability, but first I'm re-working my panel kit to put it on a diet and reduce its overall height. I haven't started chopping anything down, yet.
Bear in NM
Adventurer
Rayra,
Everything I have read indicates Series tends to be more shade tolerant. Maybe I have misunderstood. But yes, after my discussion with my solar guy, before buying any additional panels I will be researching on construction. Right now, with my starter battteries being lead acid, and my recent look at Lifepo, I am thinking about installing two systems in the van. Right now, I am looking at charging lead acid and agm, with the alternator probably not doing any work on the house battery. I have a small agm bank in my solar suitcase, and will run with that for a while. It served me well last summer. I am looking very hard at the Lifepo down the road. The plan now is to make sure any work on the electrical side on the inside of the van needs wiring/fusing to handle perhaps up to 100 amps.
Back on topic, the aiming was a little tongue in cheek. There are a lot of ways to skin that critter, as you noted. The cross rails on my van roof are stout, and one ton suspension helps.
Craig
Everything I have read indicates Series tends to be more shade tolerant. Maybe I have misunderstood. But yes, after my discussion with my solar guy, before buying any additional panels I will be researching on construction. Right now, with my starter battteries being lead acid, and my recent look at Lifepo, I am thinking about installing two systems in the van. Right now, I am looking at charging lead acid and agm, with the alternator probably not doing any work on the house battery. I have a small agm bank in my solar suitcase, and will run with that for a while. It served me well last summer. I am looking very hard at the Lifepo down the road. The plan now is to make sure any work on the electrical side on the inside of the van needs wiring/fusing to handle perhaps up to 100 amps.
Back on topic, the aiming was a little tongue in cheek. There are a lot of ways to skin that critter, as you noted. The cross rails on my van roof are stout, and one ton suspension helps.
Craig
Bear in NM
Adventurer
My German is pretty dusty, but there are enough pictures to get the idea. That is darn clever....
Thanks for the link.
Craig
Thanks for the link.
Craig
Dan Grec
Expedition Leader
No question, keep it simple and have them mounted to the roof, always connected.
I have 200 watts hard mounted on the roof of mine, and at this point I basically forget they are there.
If I camp with the roof facing East the battery is full before I'm finished my coffee at 8am.
I recently traveled/camped with a couple that have 400w that is removable and they need to move them into the sun.
When we're in a parking lot or buying gas - mine is charging, theirs isn't even connected.
Early AM in camp - mine is charging, theirs isn't because they put it away for the night.
Sitting in camp relaxing, mine is charging while I do nothing, they have to get up every 2 hours and shuffle the panels around.
Also something I noticed moving their panels around each and every day - the cables are wearing out FAST and it's going to be a constant battle to keep it all running... obviously our use-case is a little different because we live full-time in out vehicles.
Personally, the beauty of solar is that it's passive - I do nothing and my batteries are full, and that's the way I want it!
-Dan
I have 200 watts hard mounted on the roof of mine, and at this point I basically forget they are there.
If I camp with the roof facing East the battery is full before I'm finished my coffee at 8am.
I recently traveled/camped with a couple that have 400w that is removable and they need to move them into the sun.
When we're in a parking lot or buying gas - mine is charging, theirs isn't even connected.
Early AM in camp - mine is charging, theirs isn't because they put it away for the night.
Sitting in camp relaxing, mine is charging while I do nothing, they have to get up every 2 hours and shuffle the panels around.
Also something I noticed moving their panels around each and every day - the cables are wearing out FAST and it's going to be a constant battle to keep it all running... obviously our use-case is a little different because we live full-time in out vehicles.
Personally, the beauty of solar is that it's passive - I do nothing and my batteries are full, and that's the way I want it!
-Dan
IdaSHO
IDACAMPER
Dan, if your batteries are fully topped off every morning by 8am, then you dont even need solar.
Most of your other examples lean the same way.
As I mentioned earlier, if you are moving often, every day or every other day, you can charge via the vehicle charging system, and simply do not need solar at all.
If you park for more than a few days, a week, or longer, you start getting into solar needs as you simply get beyond simply increasing your battery bank size.
Most of your other examples lean the same way.
As I mentioned earlier, if you are moving often, every day or every other day, you can charge via the vehicle charging system, and simply do not need solar at all.
If you park for more than a few days, a week, or longer, you start getting into solar needs as you simply get beyond simply increasing your battery bank size.
C-Fish
Adventurer
IdaSHO, you make a valid argument. But...
We have a 100w panel on the roof of the FJC and it is working all the time as well. For us, it is piece of mind that while the vehicle is parked, the battery (one single AGM) is charging to offset the draw from the fridge. We chose solar vs a dual battery setup for weight reasons.
I probably don’t need the help of the panel (most days), but it is nice knowing it is there...especially when temps are over 100°.
We have a 100w panel on the roof of the FJC and it is working all the time as well. For us, it is piece of mind that while the vehicle is parked, the battery (one single AGM) is charging to offset the draw from the fridge. We chose solar vs a dual battery setup for weight reasons.
I probably don’t need the help of the panel (most days), but it is nice knowing it is there...especially when temps are over 100°.
IdaSHO
IDACAMPER
And thats fine, It is always nice to know its there.
I have 200 watts on the roof that are always there.
I also have an additional 200 watts of deploy able, for when I really need it (low production/filtered sun) and/or when I dont want to park in the sun just to soak up some ray
And the fact still remains. If you are charged up 100% by 8AM, you do not need solar.
You dont even need a second battery at that point, just one good battery, and maybe an auto low voltage disconnect.
I have 200 watts on the roof that are always there.
I also have an additional 200 watts of deploy able, for when I really need it (low production/filtered sun) and/or when I dont want to park in the sun just to soak up some ray
And the fact still remains. If you are charged up 100% by 8AM, you do not need solar.
You dont even need a second battery at that point, just one good battery, and maybe an auto low voltage disconnect.
Scoutman
Explorer
I would agree but I think in Dan's case above and the travels he's doing with that rig, being able to (or forced to) stay in one spot and not crank for days in the remote wilds of Africa would still facilitate solar. I imagine his use is pretty low with fridge, pump, charging, and lights for one person being the bulk of his use.
Dan Grec
Expedition Leader
I disagree.
What I'm saying is that by 8am my solar can replenish what was used overnight by the fridge.
And yes, I often sit still for many days without starting the engine, so obviously I do need solar.
-Dan