Non-Bicep Powered Solar Panel Tilter

[SiennaGuy]

I've read about how tilting solar panels can allow you to generate more power. I've seen the tilting mounts that AM Solar carries and they look good. What I don't like about them is that they're bicep powered and require climbing up on the roof to operate. I'd love to be able to stand on the ground and press a button.

Are there any automatic panel raisers for RVs that:

a. Don't weigh a ton and don't require a ton of electricity to operate.

b. Are simple, with as few moving parts as possible.

c. Are reasonably priced?

[alano]

Even if such a thing existed, would it continuously try to point the panels in the optimal direction? Would you need to constantly adjust accordingly to the sun's angle. How would it work if your trailer is not aligned in the preferred orientation?

i think the easiest solution is to compensate by oversizing your array to some degree.

[WayneG]

I use the AM Solar rocker mounts, I had to modify them to be able to get a tilt range of 10 to 20 degrees on a curved Airstream roof and even then the left & right panels are not aiming at the same angle, I can only get them close.

You still have to find the perfect parking position for the suns arc to align with the panel orientation.
Most of my wanders are less than a week so I am leaving my panels in a fixed position, and I try to park for best sun to panel angle and live with the results.
As mentioned by Alano, more panels is the easiest solution, if you have the room. The chart & link below is made for stationary panels, but it gives you a good idea of the losses you will have for all angles.

https://www.civicsolar.com/resource/...-energy-output

[lewster]

A reasonable, remote controlled tilt mechanism for RV-mounted panels would be sort of a holy grail. I'm certain that it can be engineered, but not cheaply!!

OTOH, I set all of the panels the I install as flat as possible by using extended rocker feet on the outside edges of an Airstream trailer, with shorter feet towards the center. This allows for the same amount of solar radiance to reach all panels at the same time.

I also have lots of folks that are using a Telesteps ladder with a padded top for manual panel tilting. Small, light and no problems, as the panels require almost no effort to lift for the addition of the tilt bars.

[Papa smurf]

[QUOTE=lewster;1762626]A reasonable, remote controlled tilt mechanism for RV-mounted panels would be sort of a holy grail. I'm certain that it can be engineered, but not cheaply

I am certainly not an engineer but since I think there are quite a few here i would like to know what they think of using an electric window opener for this application. you can see some at solarbreezeinfo.com and the beauty of it is that they run on solar. I am sure it is not the perfect solution but it could be a starting point. What do you see as potential problems with this solution and do you think there is a way to tweak it to make it usable.

[bci]

I've seen RV mounted sun tracking solar setup at quartzite. I didn't get the vender information - The class A it was on was way out of our reach. Here are some links that look to be RV compatible that track the sun:

1. This is real close to the system I saw (youtube)

2. Solar tracking with Satellite.
3. DIY Solar tracker

[SiennaGuy]

The Oyster SamySolar Automatic Satellite Dish and Solar Panel System looks like what I envisioned, but each mechanism/75 watt panel/satellite dish combo costs almost $3900 US. I couldn't find a price for a system without a satellite dish to allow for a configuration with multiple movable panels. Somebody who knows more about enginering than I do should go back to the drawing board and come up with a cheaper system.

[lewster]

Full-on solar trackers are a whole other ball of wax, as they say. A mechanism for simple panel tilting is far simpler to conceive. The problem is making it withstand driving down the road at highway speeds and be ready to use when parked. It also must be able to tilt the panels from either side (one side would be far less complicated to fabricate).

For my money (and yes, I have a master's degree in engineering also), I would buy that ladder and simply use AM Solar's tilting rocket feet on your panels and their tilt bars. On a 4 panel system, it might take 10 minutes to tilt all 4 panels for your net 30% gain. Put the money you save into more vacation time, more adult beverages or whatever you desire, as the savings will be substantial!!

[SiennaGuy]

Since tracking panels don't sound reasonable, what's the maximun solar power that anybody has gotten mounted on their EXT Grand Tour? I'm still in the planning stages and I love camping along the foggy coast. I figure that if I install as much power as possible, I should get about half of the maximum amount of juice out of the system.

It also looks like a ladder aerobics class is in my future. It will do my ticker some good.

[vinstream]

Depending on the amount of roof space it maybe cheaper in the long run to simply add two more panels to your system to make up for the 10% to 15% loss of not being directed to the sun... I like too have 1/3 of my panels mounted on my roof and the other 2/3 of my panels that plug into the system when boondocking so I can position them for optimum use... I agree this can be a hassle but it gives my flexibility in my system and allows me to park under trees and still get sun to most of my panels. I find that you are also better off having more battery storage than solar system and would rather put my $$$ into the battery.... Hope this helps give other options.

[bci]

Originally Posted by SiennaGuy

Since tracking panels don't sound reasonable, what's the maximun solar power that anybody has gotten mounted on their EXT Grand Tour?

I have 2x85 watt panels on my 2007 classic, on good days, my meter reads incoming about 8.5 amps with full sun.

See Solar Calculations

[lewster]

Originally Posted by SiennaGuy

Since tracking panels don't sound reasonable, what's the maximun solar power that anybody has gotten mounted on their EXT Grand Tour? I'm still in the planning stages and I love camping along the foggy coast. I figure that if I install as much power as possible, I should get about half of the maximum amount of juice out of the system.

It also looks like a ladder aerobics class is in my future. It will do my ticker some good.

Here is a shot of brandy new Grand Tour that is getting 400 watts of solar, Blue Sky 2512 iX-HV with iPN-PRO remote, 800 amp/hour lithium battery and Magnum MSH-3012M Hybrid inverter/charger. Along with being able to operate everything in the coach from the inverter, the A/C will run for around 5 hours during the day just from the solar and battery!

[alano]

Why did you use the Blue Sky 2512 iX-HV when they say in their datasheet, "Recommended maximum, 340W with 36 cell modules / 270W with 60 cell modules"

[lewster]

Originally Posted by alano

Why did you use the Blue Sky 2512 iX-HV when they say in their datasheet, "Recommended maximum, 340W with 36 cell modules / 270W with 60 cell modules"

These are 32 cell panels. Have been using the 2512iX-HV for many years with no controller problems. We (AM Solar) typically place up to 400 watts with the 2512 Blue Sky unit: http://www.amsolar.com/home/amr/page...6pro_core.html

I'll post a shot of the iPN-PRO output screen when it goes live in a couple of days.

[alano]

Your customer is leaving energy on the table! 400 W / 13.6 V = 29.4 A and 400 W / 12 V = 33.3 A. Even if you account for their typical converter inefficiency of 4%, that should still generate 27.6 A at 13.6 V and 31.3 A at 12 V in optimal conditions. The manual says this converter will current limit the output to 25 A so you're leaving on the table between 10 and 25% of the peak energy. I wouldn't specify this configuration with 400 W of solar input.

[lewster]

Originally Posted by alano

Your customer is leaving energy on the table! 400 W / 13.6 V = 29.4 A and 400 W / 12 V = 33.3 A. Even if you account for their typical converter inefficiency of 4%, that should still generate 27.6 A at 13.6 V and 31.3 A at 12 V in optimal conditions. The manual says this converter will current limit the output to 25 A so you're leaving on the table between 10 and 25% of the peak energy. I wouldn't specify this configuration with 400 W of solar input.

Alan,

You are looking at this from a theoretical engineering view and not a real world one. There is a significant difference between STC ratings (Standard Operating Conditions) and NOCT (Normal Operating Cell Temperatures)

I have included an explanation from AM Solar's web site so others can see the difference. Blue Sky also calls for derating their open circuit current and short circuit current by 1.25% to account for the real world factors of solar panel output. From their manual:

Voltage, current and power produced by PV modules fluctuate widely with operating conditions. As a result a set of test conditions referred to as Standard Test Conditions (STC) are used to rate modules in a meaningful manner and accurately predict real world performance. STC ratings are not maximum or optimal ratings. Conditions can be present where VOC and ISC approach 1.25 times STC ratings which is why National Electrical Code and our recommendations call for 1.25 derating of both VOC and ISC. Yet in real world conditions IMP actually seen is commonly only about 75 – 80% of IMP at STC.



STC - Solar Panel manufacturers use what are called STC (Standard Test Conditions) when they evaluate solar panels in a solar simulator called a flash tester. During flash testing, solar panels are exposed to artificial sunlight with an intensity of 1000 watts per square meter. (Bear in mind, 1000 watts per square meter of sunlight would only be reached around solar noon, with the panel squarely facing the sun, just after a rain shower has washed all the dust out of the air.) The temperature is 25°C (77 °F) and the atmospheric density is 1.5. The output of the panel under these Standard Test Conditions is what gives the panel it’s rating. All solar panels are rated using this same method, meaning that a 100 watt solar panel from one manufacturer will produce that same 100 watts under STC as a 100 watt solar panel from another manufacturer. Think of the STC rating of a solar panel as similar to an EPA mileage rating for a vehicle. How often does your mileage exactly match the stated EPA rating?


NOTE: Atmospheric density is the optical path length through the Earth's atmosphere for light from a celestial source. As light passes through the atmosphere, it is attenuated by scatter and absorption; the more atmosphere through which it passes, the greater the attenuation. Consequently, celestial bodies at the horizon appear less bright than at their zenith. An atmospheric density of 1 is what you would find when looking straight up from sea level at the sun when it is directly overhead (which never occurs in North America).

If you are anywhere north of the Tropics (23.5 degrees of latitude), the sun is never going to be directly overhead and you will never see an atmospheric density of 1. Since solar panel manufacturers operate at varying degrees of latitude and elevation, some sort of standard had to be developed so all solar panels could be tested and rated under identical conditions and customers could have a reliable basis for comparison. A number had to be agreed upon, as a result, 1.5 was adopted for use in the STC. This is roughly equivalent to 500’ above sea level where the majority of the Earth’s population lives.

NOCT – Because Standard Test Conditions hardly resemble "Real World" conditions, utilities and municipalities have adopted what they call NOCT (Normal Operating Cell Temperature) ratings in order to more accurately issue rebates and tax credits. NOCT incorporates more reality into their conditions by assuming the following: 800 watts per square meter of sunlight irradiance, an average of 20°C (68°F) air temperature and an average wind velocity of 1 meter per second (2.24 miles per hour) with the back side of the solar panel open to that breeze (as opposed to being on a roof where heat builds up under the panels). 


When you consider that solar cells are dark blue to almost black, they soak up sunshine and get quite hot. Under these conditions, average cell temperature (not air temperature) was found to be about 48°C (118.4°F). Some panels operate a little warmer and some are a little cooler. What you need to know is that ALL solar panels experience some degree of voltage drop when exposed to heat. Since Volts x Amps = Watts, the power output of the solar panel is reduced when the cells get hotter.


Since most solar panels in use on RVs are laying flat on the roof, they are operating at even higher cell temperatures than what would be expected from NOCT (as described above, with the back of the solar panel being open to airflow). This is why you want to keep the panels raised up off of the roof by a few inches. Even then, cell temperatures as high as 70°C (158°F) have been measured on a day when the air temperature was only 80°F.

The point of this is not to imply that panel manufacturers are purposely trying to deceive you. It is because "real world" operating conditions are so variable that they had to come up with some standard test conditions so that all panel ratings are derived after being subjected to the same conditions as every other panel. On average, you will be getting about 75% to 80% of the power you pay for. Know that the 100 watt solar panel you are about to buy will only give you about 75 to 80 watts of power during peak sun hours on an average day. There will be days when you get the full rating of the panels but those days will be few and far between. Likewise, there will be days when it is dark and cloudy and you will get only about 10 to 20 watts out of that 100 watt panel.

Considering that one rarely sees full output from ANY solar module, there is very little, if anything, that is left on the table from using the 2512iX-HV and a 400 watt array. If you look at the readings that the iPN-PRO give you for the individual solar charge controllers, you will generally see real-world input voltages approaching 20VDC from the array. Using your math, 400 watts (ideal) ÷ 20VDC = 20 amps input to the controller. The input will actually be less than that most of the time as you rarely see the full 400 watt output from the array.

[unifreck]

Thank you Lew for the detailed explanation. AEW

[BoldAdventure]

Originally Posted by alano

Your customer is leaving energy on the table! 400 W / 13.6 V = 29.4 A and 400 W / 12 V = 33.3 A. Even if you account for their typical converter inefficiency of 4%, that should still generate 27.6 A at 13.6 V and 31.3 A at 12 V in optimal conditions. The manual says this converter will current limit the output to 25 A so you're leaving on the table between 10 and 25% of the peak energy. I wouldn't specify this configuration with 400 W of solar input.

Despite Lew's long explanation about "real world"; this was my real world results for half a year. I hit 25 amps all the time with the 400 watts. When I switched to the larger SB3024IL suddenly I hitting around 30 amps.

I've added more panels now, but to say I was a little annoyed that that they recommend a unit limited to 340W for a 400-watt array is an understatement. The problem here is you're maxed out right out of the gate. If you decide to add more panels.

When I first bought my kit though, I had not really gotten into the depth of understand I have now after almost a year living with solar powering everything.

I'm sure it works for most since I have several friends with the 2512iX and the 25amps worked well enough for most of the year. But the bump in power was appreciated when I started really geeking out and adding lithiums and ground deploy and stuff.

I will say, I really like that the 2512 can be slaved or tethered if you will to the 3024. The 3024 handles my roof and the 2512 now handles 300 watts of ground deploy.

[vinstream]

Originally Posted by BoldAdventure

Despite Lew's long explanation about "real world"; this was my real world results for half a year. I hit 25 amps all the time with the 400 watts. When I switched to the larger SB3024IL suddenly I hitting around 30 amps.

I've added more panels now, but to say I was a little annoyed that that they recommend a unit limited to 340W for a 400-watt array is an understatement. The problem here is you're maxed out right out of the gate. If you decide to add more panels.

When I first bought my kit though, I had not really gotten into the depth of understand I have now after almost a year living with solar powering everything.

I'm sure it works for most since I have several friends with the 2512iX and the 25amps worked well enough for most of the year. But the bump in power was appreciated when I started really geeking out and adding lithiums and ground deploy and stuff.

I will say, I really like that the 2512 can be slaved or tethered if you will to the 3024. The 3024 handles my roof and the 2512 now handles 300 watts of ground deploy.

Question:

Like you I have both permanent mount on roof, 4 30 watt panels on roof... Because of limited of larger than normal sky lights and the roof on vintage style trailers is limited...space see picture.


I also have 3 100 watt ground deploy like you but am thinking about adding a another 100 watt... Due to loss or real world.

My solar controller stated limit is 440.

What is your total watt of panels on both roof and ground deploy?

[BoldAdventure]

Current roof is now 505-watts - using three of the original GS-135 panels and one GS-100 panel. And ground is made up of three GS-100 panels for 300-watts. The roof is parallel but the ground is series for ease of setup. I need to take a photo sometime, but DIY'd my own setup and then used a waterproof connector on the battery box that goes into the Airstream.