RV Solar - Expected Output

[zachreborn]

I have what might be one of the most complex and very simple questions possible. I understand that the weather, place in the world, and time of year will change this drastically. What are some real life example outputs from a 800W solar array?

To expand further, I just installed 8x Renogy 100W flexible panels on the top of my Airstream RV. I had hoped to be seeing 600-700W from the array during peak overhead sunlight in August in Illinois but I've really only been seeing about 450W. I'd love to hear some real world examples of folks with fixed panels what they're getting out of their systems. My main goal is to make sure that I haven't made a mistake in how I've set this up or if I shouldn't wire them in a more optimal way.

Here is my system:

• 8x 100W Renogy flexible solar panels
  • (4p2s is how I believe I've seen it written. Or put simply I have 2 sets of 4 in series)
  • Each side of the RV is in series (4) and each series is in parallel (2 of them)
• Victron MPPT Solar Charger 150/85
• 4x Battleborn GC3 batteries - 1080ah (270ah each)

Victron Graphs:
A note prior to the graphs, I had ample batteries left to charge.

 

[Bobert]

I have what might be one of the most complex and very simple questions possible. I understand that the weather, place in the world, and time of year will change this drastically. What are some real life example outputs from a 800W solar array?

To expand further, I just installed 8x Renogy 100W flexible panels on the top of my Airstream RV. I had hoped to be seeing 600-700W from the array during peak overhead sunlight in August in Illinois but I've really only been seeing about 450W. I'd love to hear some real world examples of folks with fixed panels what they're getting out of their systems. My main goal is to make sure that I haven't made a mistake in how I've set this up or if I shouldn't wire them in a more optimal way.

Here is my system:

• 8x 100W Renogy flexible solar panels
  • (4p2s is how I believe I've seen it written. Or put simply I have 2 sets of 4 in series)
  • Each side of the RV is in series (4) and each series is in parallel (2 of them)
• Victron MPPT Solar Charger 150/85
• 4x Battleborn GC3 batteries - 1080ah (270ah each)

Victron Graphs:
A note prior to the graphs, I had ample batteries left to charge.
View attachment 107163
View attachment 107160
View attachment 107161
View attachment 107162

I don’t have an 800 watt array on my camper. But divided by four my array equals just over 800 Watts at 3240 watts. I’m full sun this time of year I max out at just above 2000 watts. Divided by 4 that’s just over what you re getting and my panels are raised 8” off the roof and run relatively cool.

 

[sneil]

I have what might be one of the most complex and very simple questions possible. I understand that the weather, place in the world, and time of year will change this drastically. What are some real life example outputs from a 800W solar array?

To expand further, I just installed 8x Renogy 100W flexible panels on the top of my Airstream RV. I had hoped to be seeing 600-700W from the array during peak overhead sunlight in August in Illinois but I've really only been seeing about 450W. I'd love to hear some real world examples of folks with fixed panels what they're getting out of their systems. My main goal is to make sure that I haven't made a mistake in how I've set this up or if I shouldn't wire them in a more optimal way.

Here is my system:

• 8x 100W Renogy flexible solar panels
  • (4p2s is how I believe I've seen it written. Or put simply I have 2 sets of 4 in series)
  • Each side of the RV is in series (4) and each series is in parallel (2 of them)
• Victron MPPT Solar Charger 150/85
• 4x Battleborn GC3 batteries - 1080ah (270ah each)

My RV system is a bit smaller, I have only 290W of panels (planning on upgrading to 6x200W panels) and 3 100Ah Battleborn batteries with the same Victron MPPT 150/85. I'm in Colorado so maybe a little bit further south in latitude than you, but can regularly see 200W output and on some occasions close to 290W. I'd agree with your expectation of 600-700W during the time you mentioned as well.

Maybe start by checking the panel configuration and connections along with the MPPT settings.

 

[DW SD]

I have 300W x 3. 60 cell house type panels. I've seen as much as 650W out of the MPPT (Magnum) SCC, never real close to rated. And that'd be with maximized geometry (mid day sun). And mine our mounted flat.

Given your description, I'd expect less efficiency. The geometry of your panels and curved roof all never being square to the sun should cause further reduced output compared to a flat setup.
I do notice reduced output if mine aren't completely clean, also. Maybe as much as 10% further reduction.
My $0.02.
Doug

 

[RF_Burns]

You didn't say exactly where you are, but for central IL, its about 40 degrees North Latitude. So the furthest north that the sun is perpendicular to the earth is at 23 degrees on June 21, so you are 17 degrees north of that. Therefore with flat panels lying horizontally on the roof, the best you get is 73 degrees, not fully perpendicular at noon time. In August the sun may be down to the low 60's degrees (in another month, Sept 21 it will be directly over the equator so at 50 degrees at noon time.
Further taking into account the curved roof of an Airstream (you said flexible panels), you may be doing really good.

Here is a site that lets you calculate the sun angle based on time of year and time of day.

Calculation of sun’s position in the sky for each location on the earth at any time of day [en]

Calculation of sun’s position in the sky for each location on the earth at any time of day. Azimuth, sunrise sunset noon, daylight and graphs of the solar path. [en]

www.sunearthtools.com

 

[Lt.Dan]

450w from an 800w array with flexible panels fixed to an RV roof is very typical IMO.

 

[HRTKD]

As stated by Lt.Dan, flex panels aren't known for producing what they're rated for.

I have 640 watts of rigid panels on the roof of my RV and I will get 550 watts at high noon if the panels are clean and the sky is clear.

 

[zachreborn]

Thanks everyone for your help and feedback! Very useful for the sanity check. Lots of good experience and information.

 

[chrisski]

On my RV roof, i have 1050 watts of flexible panels set up 2S3P on a 30 amp SCC for a 24 volt battery system and I max out the SCC at 30 amps, or 810 watts.

Shading really prevents that array of panels from maxing out at 30 amps most of the day. A single shadow on any panel wrecks the output Of the 2 in series. I have air conditioners and roof vents that shade panels throughout the day.

 

[MrThisIsME]

. My main goal is to make sure that I haven't made a mistake in how I've set this up or if I shouldn't wire them in a more optimal way.

Here is my system:

• 8x 100W Renogy flexible solar panels
  • (4p2s is how I believe I've seen it written. Or put simply I have 2 sets of 4 in series)
  • Each side of the RV is in series (4) and each series is in parallel (2 of them)
• Victron MPPT Solar Charger 150/85
• 4x Battleborn GC3 batteries - 1080ah (270ah each

Judging by your graph voltage you have a 2p4s system not what you stated, but your text description confirms this.

As DW SD eluded to, I wonder if the panels being curved on the roof comes into play. Are the panels lengthwise across the beam of the RV (meaning the most curved way to lay them)? My thinking is if curved there would be a differential on the individual cells, much like shading, further reducing the already low efficiency of flexible panels.

 

[fratermus]

What are some real life example outputs from a 800W solar array?

I have 750w flat-mounted on my van (see avatar) with several inches of airgap. Most of the time it's running at 50% of rated or less since

• I have a relatively small bank that is typically charged well before local solar noon when Big Power might be made; and
• I don't run particularly big loads

Under exceptional and temporary conditions (cloud-edge effect around noon with low SoC) I have briefly seen 91% of rated.

My setup has "excess" panel to compensate for poor conditions, not because I am trying to get the Full Pull out of them. Under poor conditions they might be making 5-20% of rated.

 

[chrisski]

In my signature block there’s a calculator that is pretty good at giving output. It’s adjusted for your location and your weather.

Problem is it’s unshaded panels, so some estimate is required to guess the percentage you lose for RV obstructions.

 

[Generis]

In my signature block there’s a calculator that is pretty good at giving output. It’s adjusted for your location and your weather.

Problem is it’s unshaded panels, so some estimate is required to guess the percentage you lose for RV obstructions.

Thanks for the calculator!