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05-24-2018, 06:42 PM
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#1
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Senior Member
Brand: DRV
State: Texas
Posts: 311
THOR #9543
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Solar output
I installed four 150 watt panels with 8.2 aH output and a 60 amp mppt controller. On the maiden 3-week voyage, the most output recorded in the middle of the day, full sun, no clouds, and no shade was mid 400’s for wattage and upper 20’s for amps. Is that normal? Is it unrealistic to expect the full 600 watts and 33 amps?
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05-24-2018, 07:01 PM
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#2
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I Think We're Lost!
Brand: Still Looking
Model: Tiffin Wayfarer 24 BW
State: New York
Posts: 22,195
THOR #8860
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70% percent or so... That's probably about what you can expect.
That's not to say that you can't coax more out of it...
__________________
"What: me worry?"
Good Sam Member 843599689
Current coach: Tiffin Wayfarer 24 BW
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05-24-2018, 07:06 PM
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#3
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Senior Member
Brand: DRV
State: Texas
Posts: 311
THOR #9543
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Thank you, Bob.
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05-24-2018, 07:38 PM
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#4
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I Think We're Lost!
Brand: Still Looking
Model: Tiffin Wayfarer 24 BW
State: New York
Posts: 22,195
THOR #8860
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When it comes to solar power: I've been doing a lot of looking, reading, and shopping!
__________________
"What: me worry?"
Good Sam Member 843599689
Current coach: Tiffin Wayfarer 24 BW
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05-24-2018, 07:48 PM
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#5
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Senior Member
Brand: DRV
State: Texas
Posts: 311
THOR #9543
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Me too; I spent hours and days, mentally putting this system together. Tech support was/is useless.
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05-24-2018, 10:35 PM
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#6
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Senior Member
Brand: Thor Motor Coach
Model: Axis 24.1
State: Florida
Posts: 613
THOR #4366
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Panel ratings are in the lab at 77 deg F. Dust on the panels, haze partial shading and temperature all impact output.
The biggest item is battery sate of charge. This determines how much the batteries will accept at any given time.
There are also other factors that come into play also. But the above are the biggies.
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2016 Axis 24.1 E-450 6 spd tranny
300 watts portable solar.
200 watts solar on the roof.
Wrangler JK dinghy
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05-24-2018, 10:57 PM
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#7
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I Think We're Lost!
Brand: Still Looking
Model: Tiffin Wayfarer 24 BW
State: New York
Posts: 22,195
THOR #8860
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You might want to check with Chance...
He's got MAD solar power knowledge!
__________________
"What: me worry?"
Good Sam Member 843599689
Current coach: Tiffin Wayfarer 24 BW
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05-25-2018, 12:42 AM
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#8
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Senior Member
Brand: DRV
State: Texas
Posts: 311
THOR #9543
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Scrub, thank you for the reply, and no offense, but I didn't understand a thing you posted. "in the lab at 77"????? "Dust, shade, hazing, temperature impact output"?? You did read, "New system, mid day, no clouds, no shade...etc"??? Right?? How does that answer my question?
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05-25-2018, 12:53 AM
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#9
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Senior Member
Brand: DRV
State: Texas
Posts: 311
THOR #9543
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Bob, who is chance?
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05-25-2018, 02:30 AM
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#10
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Senior Member
Brand: Still Looking
State: Texas
Posts: 6,187
THOR #2121
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Quote:
Originally Posted by clev
....cut..... Is it unrealistic to expect the full 600 watts and 33 amps?
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I’m no solar expert, not even close, but will say that for the typical RV installation it is indeed unrealistic to expect 100% of panel rating. Most RVs install panels flat on roof which is most practical, whereas the “ideal” rating tilts panels so they are perpendicular to sun. Depending on where you are in US, and time of year, that accounts for a significant power reduction.
Systems “may” also have enough voltage drop in wiring from panel down to controller that it becomes significant. Because you are working with low voltages and high currents, any voltage drop due to resistance in wire becomes a larger percentage of the power being transmitted through wire (compared to what we’re used to seeing).
Also, the sun doesn’t always shine with same intensity. Just because it looks sunny, it may not be as intense as what was used to rate the panel. This obviously also depends on where you are — further North usually less solar power from sun.
I have no idea what your system is, or where you did your test, but in general I'm impressed you are getting 450 watts out of 600-watt rating. Obviously my comments assume you did a typical RV installation with panels mounted horizontally.
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05-25-2018, 02:59 AM
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#11
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Senior Member
Brand: DRV
State: Texas
Posts: 678
THOR #3109
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Yes, 75% of rating is pretty good....
And dust/haze/high,thin clouds/horizonal positioning, not perpendicular to sunshine, all hurt the solar input. I take a look at my panels about every 3-4 weeks, and they are definitely dusty and have to do a little cleaning. Sometimes a good shower does it for me.
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2016 Tiffin 40QBH
2015 38RSSA--traded
2005 36TK3--retired, but it was a good one
2017 F450 KR
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05-25-2018, 03:35 AM
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#12
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Senior Member
Brand: DRV
State: Texas
Posts: 311
THOR #9543
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Thank you Chance & wing; very informative. Yes, my panels are mounted horizontal and connected to each other with 10 gauge wire. Final run from the roof to the controller is 4 gauge welder’s wire. Panels were clean and garaged up until we left on the trip. Texas to Indiana, then Ohio, KY, VA, and a southerly route back to Texas. I checked the controller a few times each day while traveling and parked. Output ranged from 200’s to 400’s watts and low teens to upper 20’s for aH. Having never had solar, I didn’t know what to expect.
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05-25-2018, 12:11 PM
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#13
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Senior Member
Brand: Thor Motor Coach
Model: Hurricane 35C
State: South Dakota
Posts: 1,132
THOR #3761
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That is pretty normal. We have 400W of solar on our roof but on a good sunny day get around 280 watts due to sun angle and dust buildup on the panels themselves. On cloudy/rainy days it is substantially lower (but still has some charging capability.)
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John
2016 Thor Hurricane 35C with pups Piper and Annabelle
2013 Ford Fiesta toad
FMCA - F457085
Blog - https://traversity.us
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05-25-2018, 12:32 PM
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#14
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I Think We're Lost!
Brand: Still Looking
Model: Tiffin Wayfarer 24 BW
State: New York
Posts: 22,195
THOR #8860
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Quote:
Originally Posted by Chance
I’m no solar expert, not even close, but will say that for the typical RV installation it is indeed unrealistic to expect 100% of panel rating. Most RVs install panels flat on roof which is most practical, whereas the “ideal” rating tilts panels so they are perpendicular to sun. Depending on where you are in US, and time of year, that accounts for a significant power reduction.
Systems “may” also have enough voltage drop in wiring from panel down to controller that it becomes significant. Because you are working with low voltages and high currents, any voltage drop due to resistance in wire becomes a larger percentage of the power being transmitted through wire (compared to what we’re used to seeing).
Also, the sun doesn’t always shine with same intensity. Just because it looks sunny, it may not be as intense as what was used to rate the panel. This obviously also depends on where you are — further North usually less solar power from sun.
I have no idea what your system is, or where you did your test, but in general I'm impressed you are getting 450 watts out of 600-watt rating. Obviously my comments assume you did a typical RV installation with panels mounted horizontally.
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This is Chance...
Thanks for chiming in at the exact right time!
__________________
"What: me worry?"
Good Sam Member 843599689
Current coach: Tiffin Wayfarer 24 BW
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05-25-2018, 01:19 PM
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#15
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Senior Member
Brand: Still Looking
State: Texas
Posts: 6,187
THOR #2121
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Quote:
Originally Posted by Bob Denman
This is Chance...
Thanks for chiming in at the exact right time!
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Glad to help, but there is a lot I also need to learn. I mostly understand the engineering fundamentals from when I was in school a very long time ago.
I did build a mean solar oven as a class project that could cook biscuits. And the total cost had to be really cheap — like $10 (back then) which made it tough to find materials that would work.
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05-25-2018, 01:34 PM
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#16
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I Think We're Lost!
Brand: Still Looking
Model: Tiffin Wayfarer 24 BW
State: New York
Posts: 22,195
THOR #8860
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I figure that you know the "alternate fuel" stuff; even better than I know the best places to find good jokes!
__________________
"What: me worry?"
Good Sam Member 843599689
Current coach: Tiffin Wayfarer 24 BW
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05-25-2018, 01:38 PM
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#17
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Junior Member
Brand: Still Looking
State: Virginia
Posts: 4
THOR #6692
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The only think I can add is;
Did you have any 12V items on? or was that just what the battery's were accepting as a charge.?
It could be possible you have more available but the battery's were accepting all they could.
Just because you have 600 watts and 33 amps does not mean it all being used.
Turn on some 12v items and see what the meter says.
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05-25-2018, 02:55 PM
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#18
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Senior Member
Brand: DRV
Model: 39RESB3
State: Florida
Posts: 240
THOR #5499
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I'm still learning, reading and asking about solar myself. The wiring has a lot to do with the amount of gain or loss, panels you select and battery bank you are depositing the solar into. There are a few YouTubers who have put in some killer systems and it gives a breakdown of what products they used, etc.
Hebard's travels and Pau Hana are two that come to mind.
I have been in contact with Brian Boone, who is an RVer traveling the country doing solar installs. People rave about his knowledge and installs. From what I read and understand, 70% is about right. Keep in mind that with the panels laying flat, any shade from the air conditioner, satellite dish, etc. affects those panels as well. I'm planning on 5 200 watt panels for my system. We already have a 5500 generator and have the Auto Generator Start system to work in conjunction with the battery voltage. Just my thoughts on the subject.
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05-25-2018, 04:27 PM
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#19
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Senior Member
Brand: Still Looking
State: Texas
Posts: 6,187
THOR #2121
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Quote:
Originally Posted by juicesqueezer
.....cut..... Keep in mind that with the panels laying flat, any shade from the air conditioner, satellite dish, etc. affects those panels as well. I'm planning on 5 200 watt panels for my system. ....cut.....
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Shade concern is a great point, particularly as systems get larger in capacity.
If looking at 1,000 watts of nominal panel capacity, and you wire them all in parallel, the amount of current can get pretty high — like around 50 Amps.
In large systems some “experts” go with combination of series and parallel, which can reduce current significantly (normally in half), but then it risks losing a greater percentage of total installed capacity if some of the cells are shaded.
I’d assume that since you are looking at 5 panels (and odd number), that you must be planning on going with an all-parallel installation. In that case shade is bad, but not as critical.
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05-25-2018, 06:38 PM
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#20
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Senior Member
Brand: DRV
Model: 39RESB3
State: Florida
Posts: 240
THOR #5499
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Quote:
Originally Posted by Chance
Shade concern is a great point, particularly as systems get larger in capacity.
If looking at 1,000 watts of nominal panel capacity, and you wire them all in parallel, the amount of current can get pretty high — like around 50 Amps.
In large systems some “experts” go with combination of series and parallel, which can reduce current significantly (normally in half), but then it risks losing a greater percentage of total installed capacity if some of the cells are shaded.
I’d assume that since you are looking at 5 panels (and odd number), that you must be planning on going with an all-parallel installation. In that case shade is bad, but not as critical.
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Not sure yet how to wire system and may add a 6th panel and split the system into two MPPT boxes. Decisions, decisions!
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