Solar Panel Install

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drober23
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Solar Panel Install

Post by drober23 » Wed May 21, 2014 6:28 pm

Hello! Popping out of lurk mode.

I got a solar panel for the bus (Kyocera 140 Watt), and finally got it installed this weekend. The SunSaver 20L charge controller was easy to figure out and install as well. Here are a few pictures.

Image

Image

The wires come through the poptop, then down into the passenger compartment into the wheel well area. I have a hole there to the engine compartment where it ties into the battery. I'll get some pics of the wiring once I get it cleaned up.

DJ Roberts
DJ

'75 Westfalia, '79 Deluxe
(plus more busses than sense)

In a time of chimpanzees I was a monkey

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Amskeptic
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Re: Solar Panel Install

Post by Amskeptic » Thu May 22, 2014 8:21 am

drober23 wrote:Hello! Popping out of lurk mode.
I got a solar panel for the bus (Kyocera 140 Watt), and finally got it installed this weekend.
DJ Roberts
Welcome back.
Have you analyzed the aerodynamic effects/fiberglass mounting stresses?
Colin
BobD - 1978 Bus . . . . . . . . . . . 112,660 miles
Chloe - 1970 bus . . . . . . . . . . . 206,845 miles
Naranja - 1977 Westfalia . . . . . 112,885 miles
Pluck - 1973 Squareback . . . . . . 55,570 miles
Alexus - 1991 Lexus LS400 . . . 78,899 miles

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drober23
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Re: Solar Panel Install

Post by drober23 » Thu May 22, 2014 12:02 pm

No. But I used fender washers :cheers:

I'll have to keep an eye on it. I have driven about 200 miles with it in place and don't see any distress.

DJ Roberts
DJ

'75 Westfalia, '79 Deluxe
(plus more busses than sense)

In a time of chimpanzees I was a monkey

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JLT
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Re: Solar Panel Install

Post by JLT » Tue May 27, 2014 2:19 pm

I've ordered a small solar panel for my bus (a trickle charger type) and I notice it has small suction cups to attach it to the inside of a window. My question is: does the window glass itself filter out any of the electricky goodness of the sun's rays? Enough to worry about? Or should I just resign myself to mounting it on the outside and hoping it doesn't get rained on?
-- JLT
Sacramento CA

Present bus: '71 Dormobile Westie "George"
(sometimes towing a '65 Allstate single-wheel trailer)
Former buses: '61 17-window Deluxe "Pink Bus"
'70 Frankenwestie "Blunder Bus"
'71 Frankenwestie "Thunder Bus"

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Amskeptic
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Re: Solar Panel Install

Post by Amskeptic » Tue May 27, 2014 6:42 pm

JLT wrote:I've ordered a small solar panel for my bus (a trickle charger type) and I notice it has small suction cups to attach it to the inside of a window. My question is: does the window glass itself filter out any of the electricky goodness of the sun's rays? Enough to worry about? Or should I just resign myself to mounting it on the outside and hoping it doesn't get rained on?
From the Solar Electric Forum, here's "Bill":
Placing solar panels behind windows will cost you quite a bit of energy...

From the iron content of standard glass (which blocks some light), to Low-E glass which blocks some more light, to the extra reflections from additional air/glass interfaces--you will lose a lot of power (50% or more????).

Here is an example of how glass interferes with a solar cell's spectral response.

The simple test... Take any silicon solar panel (big or small) and connect it to a DVM set amps. The amp reading in sun and behind glass will give you a very exact reading on how much power you will lose (the current output of a shorted silicon solar panel is proportional to the amount of sunlight energy hitting the panel).

You also need to take into account that fact that most people's windows are near 90 degrees (vertical). And for much of North America, the ideal angles are closer to 20-40 degrees. Only in winter (and farther towards the north) does running a panel vertical not hurt you (and in some cases may help increase power collected during the winter months).
BobD - 1978 Bus . . . . . . . . . . . 112,660 miles
Chloe - 1970 bus . . . . . . . . . . . 206,845 miles
Naranja - 1977 Westfalia . . . . . 112,885 miles
Pluck - 1973 Squareback . . . . . . 55,570 miles
Alexus - 1991 Lexus LS400 . . . 78,899 miles

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asiab3
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Re: Solar Panel Install

Post by asiab3 » Tue May 27, 2014 11:15 pm

JLT wrote:I've ordered a small solar panel for my bus (a trickle charger type) and I notice it has small suction cups to attach it to the inside of a window. My question is: does the window glass itself filter out any of the electricky goodness of the sun's rays? Enough to worry about? Or should I just resign myself to mounting it on the outside and hoping it doesn't get rained on?
Are you planning on leaving it mounted?

If you're only using it camping, could you flip the suction cups around and mount it outside, then mount it inside while raining or driving?
1969 bus, "Buddy."
142k miles with me.
319k miles on Earth.

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JLT
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Re: Solar Panel Install

Post by JLT » Wed May 28, 2014 12:08 pm

asiab3 wrote: If you're only using it camping, could you flip the suction cups around and mount it outside, then mount it inside while raining or driving?
I don't know. I guess I'll find out when it arrives (maybe even in time for Maupin). I'm sure I can contrive some way of attaching it temporarily to the outside of the bus. And, no, I'm not going for a permanent mount.

Thanks for your answer, Colin. I kind of expected as much, which is why I asked. When I get it, I might be able to ask one of my more technically minded friends to help me do some experiments to measure how much loss there actually is.
-- JLT
Sacramento CA

Present bus: '71 Dormobile Westie "George"
(sometimes towing a '65 Allstate single-wheel trailer)
Former buses: '61 17-window Deluxe "Pink Bus"
'70 Frankenwestie "Blunder Bus"
'71 Frankenwestie "Thunder Bus"

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drober23
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Re: Solar Panel Install

Post by drober23 » Mon Jun 02, 2014 12:51 pm

Geeky data alert! Since I work for a company that does automotive testing, I was able to instrument my solar panel install and take data :compress: .

Data was collected for the Solar Panel Voltage, Aux Battery Voltage (camping battery), Amps used to charge the battery, bus interior temperature, and refrigerator temperature. I was keeping the fridge around 37 Fahrenheit, and it was getting around 100 degrees inside the bus on the day I am showing data from.

The setup includes the Engle MT45 refrigerator/freezer, a Kyocera 140 watt solar panel, and a SunSaver 20L charge controller. The SunSaver regulates the voltage, stopping at about 13.3 V so as not to cook the battery. When the panel voltage output drops below the battery voltage, it cuts the panel out pretty quickly. The data below is from a nice sunny day, but the panel had NO PROBLEM keeping up with the Engle even with the 2 consecutive rainy days we had in the middle of last week. I have had the panel running the fridge continuously for over a week now, and have not noticed the battery voltage drop below 12v during this time.

Ok, now for more graphs than anyone ever wants to look at! First is the data for a full day. Each vertical line represents an hour. The black line in the center is the battery voltage, and the pink line is the panel output.

Image

Next, is a look at the morning until the battery comes to full charge. You can see at the beginning that the chart, the panel has cut out (0 volts). It picks up quickly, and while the battery is coming up to charge the battery and panel voltages are locked together. Once the battery hits its "float charge", the panel voltage climbs. You will notice the "charge amps", the current actually going to the battery, drops to zero when the panel voltage climbs like this. The dips in the panel voltage are from when the refrigerator cycles on.

Image

Here is a close look at the current draw, and a calculation of the power use (watts) for a short period of time during the day. The Engle is very efficient. The internal temperature of the bus was over 100 degrees, and the fridge temp was about 37 degrees. Under these conditions the fridge was cycling "on" almost exactly 1/3 of the time. During the cool night, it would drop down to well under 20% of the time.

Image

Just to finish the geeky part... assuming a 1/3 "duty cycle" (the amount of time "on"), and an average of 3A draw during that cycle (rough averages from the graph above) one would expect it to consume a whopping 1 amp/hour of current each hour. For a 10 hour night (late in the camping season) we are talking 10 amp/hours or less per night. Again, the Engle is very efficient, and the solar panel can MORE than keep up with that load.

If you made it this far, I'm stunned. But it made me smile!

DJ Roberts
DJ

'75 Westfalia, '79 Deluxe
(plus more busses than sense)

In a time of chimpanzees I was a monkey

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Amskeptic
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Re: Solar Panel Install

Post by Amskeptic » Mon Jun 02, 2014 2:58 pm

drober23 wrote:Geeky data alert! assuming a 1/3 "duty cycle" (the amount of time "on"), and an average of 3A draw during that cycle (rough averages from the graph above) one would expect it to consume a whopping 1 amp/hour of current each hour. For a 10 hour night (late in the camping season) we are talking 10 amp/hours or less per night.
You mention 20% duty cycle at night. That will be even less than your example.
Good modern technology is a lovely thing.
Colin
BobD - 1978 Bus . . . . . . . . . . . 112,660 miles
Chloe - 1970 bus . . . . . . . . . . . 206,845 miles
Naranja - 1977 Westfalia . . . . . 112,885 miles
Pluck - 1973 Squareback . . . . . . 55,570 miles
Alexus - 1991 Lexus LS400 . . . 78,899 miles

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drober23
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Re: Solar Panel Install

Post by drober23 » Mon Jun 02, 2014 3:30 pm

Hey Colin,

The example I had earlier was from the middle of the day. That night, when the temp in the bus was about 68 degrees, the fridge would come on for 5 minutes out of 15. Here is a small bit of the chart showing the battery voltage cycling as the fridge comes on.

Image

The cooler it is in the bus, the less frequently the fridge cycles. Of course, if you put a lot of warm food/drink into the fridge it will have to run for a bit to cool it all off. But once cool, it should cycle predictably.

Still no sign of stress fatigue where the panel is mounted, but its only been a few hundred miles on the road this way. I may choose slightly larger fender washers to distribute the stresses a bit more, but I'm going to run it this way for a while and cross my fingers.

DJ Roberts
DJ

'75 Westfalia, '79 Deluxe
(plus more busses than sense)

In a time of chimpanzees I was a monkey

Heliconman
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Re: Solar Panel Install

Post by Heliconman » Sun Jun 15, 2014 2:26 pm

Looks Great DJ,

Miss you guys already and Happy Fathers Day! We may have to go with a setup like that someday. I still want to try out our Goal Zero setup for basic charging but that system you have really seems to be working very well.

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Re: Solar Panel Install

Post by Jivermo » Tue Jun 17, 2014 4:28 am

http://handybobsolar.wordpress.com/

This fellow is quite the curmudgeon, but he may be the Guru of solar panels in RV's and elsewhere. Makes for interesting reading, and ya might pick up some new knowledge. A friend of mine, after reading Handy Bob, tore out his entire solar charging system and redid it Bob's way. Swears that it is a fantastic setup.

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JLT
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Re: Solar Panel Install

Post by JLT » Sun Nov 10, 2019 8:07 pm

Update:

I finally found a good place for the solar panel. Since I have a Dormobile top, I stuck it on one of the windows. It's the kind of solar panel that actually has a VW part number ... they use it to keep Passat batteries charged while in shipment. The solar panel is flat with respect to the horizon, which works well in the summer when the sun is high, which is really when I need it because I live in the Central Valley, where driving around in an un-air-conditioned car is a pain and I use the Sienna instead. At other times of the year, I'm driving the bus enough to keep the battery charged with the alternator.

Here's the thing, though. The panel plugs into the cigarette lighter, and has all sorts of warnings on it about not having it plugged in when the engine's running. So I got a blank ignition key and put that into the ignition when the solar panel is in use. When I want to drive the bus, the key prevents me from starting it until I remove it, which reminds me to unplug the panel.
-- JLT
Sacramento CA

Present bus: '71 Dormobile Westie "George"
(sometimes towing a '65 Allstate single-wheel trailer)
Former buses: '61 17-window Deluxe "Pink Bus"
'70 Frankenwestie "Blunder Bus"
'71 Frankenwestie "Thunder Bus"

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