120 replies to this topic

[photohc]

Pics without the bricks:

 

Wire bundle

 

 

Reflection from my neighbors roof generates half an amp.

 

 

Am thinking about adding Dicor to finish the edge as there is a half inch overhang around the perimeter. however it is not needed.

 

Some of you are concerned about replacing the panel some day and getting the panel up. I decided i would remove the rectangle block and wires at the bottom of the panel and glue a new one on top. Panel is less than 1/4" thick. You still won't see it from the street.

 

It easily passed the freeway test and ...

 

Charging test Results

Turned on the Engle comp Refer Sat noon and let it draw the battery down to -77% full as of 8 am this morning.
Parked truck in front in the....morning overcast. Around 10 am -sun came out. Returned from church and groc store about 1:30...,

Checked Trimetric. 
Voltage 13.9 . 
Percent of full - 97. 
Amp 1.6 indicated..
..Renology roof panel doing its job. Refer nice cool 39*.

Checked 4 pm. 
Voltage - 13.5
Amps point - 6
Percent of full - 98
About 30 more minutes of sun - we live on east side of hill. 

(info repeated on my Build out Post)

Jim, nice job on the install. Thanks for all the performance data. That information will help other's still trying to size their system. Thought I mention that my cable layout on the roof was similar to yours but a little shorter. As I recently removed my 100 watt panel, I discovered that wind vibration on the wires caused the paint on the aluminum roof to wear off. I would recommend  that you cut off those existing MC4 connectors and shorten the wire to only the amount needed and reattach new MC4 connectors.  Those connectors cannot be floating on the roof or you will get a rubbing effect that will take the paint off the roof. You may just do away with the MC4 connectors and wire direct to the SAE plug into the roof connector. (I hear you on the warranty issue but I didn't want my roof to become a mess.) Just a thought. Harv

[RC Pilot Jim]

Hi Harv,
Thanks for your advice. Shorter cable would keep the bulk off the roof and easier to cover with a weather-proof cable cover.

I am dragging my feet to make sure the panel is working because cutting the cable voids the warranty.. Though getting it off the roof due to malfunction may damage it in the process.

So far it's working great. Trimetric monitoring the percentage of full. Running errands and parking slowly increases the percentage of full. Yesterday it gained 2 percentage points. Highest charge percentage alternator/solar so far is 99%. Even with all monitors off percent of full drops 1 % per day. Plugging into 110 volt charger/maintainer tops it off.

Before going on a trip I would still run the 110 volt charger/maintainer to cool the refer and top off battery.

Edited by RC Pilot Jim, 26 September 2014 - 03:10 PM.

[RC Pilot Jim]

Testing charging amps.
I haven't see 5.7 charging amps since testing the panel tilted toward the sun before installing. Of course the battery hasn't been below 80% since installing either.

As DrJ suggested I unplugged the roof solar panel and turned on the Fridge. Goal was to discharge bat to 60% ....which took 36 hours. Moved truck into the sun, Plugged in roof panel. Results 3.1 amps charging......

Of course its late Sept so sun is lower in the sky...and missed the noon hour (didn't get truck in sun till 2:30 pm).

Conclusion is the 100 watt panel at 54% efficiency is about the same output as the 60 watt portable so I should have enough for the desert in Nov-Feb.

Put truck back under car-port, plugged in the 110 volt shell-shore power 'charger-maintainer'......40 hours to charge from 60% to 98%. Charging voltage 13.7. Amps point one.

Edited by RC Pilot Jim, 27 November 2014 - 09:26 PM.

[brianjwilson]

As DrJ suggested I unplugged the roof solar panel and turned on the Fridge. Goal was to discharge bat to 60% ....which took 36 hours. Moved truck into the sun, Plugged in roof panel. Results 3.1 volts charging......

This is supposed to read "3.1 AMPS charging", correct?

Edited by brianjwilson, 30 September 2014 - 03:50 AM.

[RC Pilot Jim]

Correct Brian.
I thought 3.1 would be pretty good because you can't tilt the panel. The reason many of the guys have 2 or more panels (6.2 amps). In June when sun is high charging rate will be higher.

Our basic system running everything only draws 3 to 5 amps. The Engle top loader Fridges are super efficient. So we should be fine. I will know for sure after my 7 day semi-annual trip to the hot springs in November.

Will take the 60 watt as back up.

Edited by RC Pilot Jim, 05 October 2014 - 11:10 PM.

[DrJ]

Testing charging amps.
I haven't see 5.7 charging amps since testing the panel tilted toward the sun before installing. Of course the battery hasn't been below 80% since installing either.

As DrJ suggested I unplugged the roof solar panel and turned on the Fridge. Goal was to discharge bat to 60% ....which took 36 hours. Moved truck into the sun, Plugged in roof panel. Results 3.1 volts charging......

Of course its late Sept so sun is lower in the sky...and missed the noon hour (didn't get truck in sun till 2:30 pm).

Conclusion is the 100 watt panel at 54% efficiency is about the same output as the 60 watt portable so I should have enough for the desert in Nov-Feb.

Put truck back under car-port, plugged in the 110 volt shell-shore power 'charger-maintainer'......40 hours to charge from 60% to 98%. Charging voltage 13.7. Amps point one.

That's disappointing to only get 3.1 amps of charge. The tilt of the panels, time of the year, sun exposure all play a part in the amount of energy you can capture.

We take a camping trip during our Christmas break and I'm always amazed how much more difficult it is to recharge then. The sun is much lower on the horizon and the daylight hours are much less.

Still, I would have guessed you would have noted higher than 3.1 amps, in September where you live.

What gauge wire is run to the batteries and solar charger?

[RC Pilot Jim]

Hi Jeremy,

Panel wire is 10 gauge. Roof to controller is 12. I may be losing current through the M4 connectors on the roof.. I checked the voltage (with a volt meter) from the panel to the charge controller and it is spec - 17.7 volts.

 

I used the 20m setting on the multi-meter and recorded the amps from the panel to the charge controller. This reading matched the Trimetric.  Including photo in case I was reading the wrong scale.

 

 

 

 

 

[camper101]

This brings up something I was just wondering about (hopefully not off-topic -- Jim I'm happy to move this to it's own thread if so). Is that an accurate way to tell how efficient your wiring is:

1. Measure voltage at the panel (let's say Jim's example you get 17.7)

2. Measure voltage at the end of your wiring run, after any connectors -- right where you'd attach to the charge controller

 

If you got 17.7 again in step 2, would that mean there's no voltage loss, and therefore you will get all of the amps you can possibly get out of your system?

[RC Pilot Jim]

Yes 101,

When I set up and tested the 60 watt portable  panel I tilted it and aimed it at the sun. Used my voltmeter to test the output which equaled 20.5 volts. Then plugged in 50 feet of 12 gauge wire - one red, one black wire (12-2) took the reading again = still 20.5  volts... or NO loss in voltage. Then I plugged it into the Morningstar 10L controller and read the volts to the battery = 14.2 (no load).

 

The 100 watt bendable Renology is glued to the roof and so far due to the angle (September) of the sun I can't get more than 3.1 amps out of it. Before gluing it to the roof  I aimed it at the sun, tilted it and checked the meter and it read 5.8 amps. Next June when the sun is high in the sky...for about one month panel should deliver close to what it is rated to produce.

 

A portable is more efficient because it can be angled towards . and located in the sun.  The downside - you have to  carry and store it and there is no way to lock it up when it is being used.  That is reason DrJ and others have two-three additional panels on roof - to run all their gadgets.

 

My only gadget is charging my plane batteries because my lights are LED, the Fant fan very frugal, as is the "Refer".

 

In my application 3.1 amps is enough to run the "Engle" MT 35 (1.5 amp draw) with a little left over to charge the battery. 

 

Hope this answer helps.

Edited by RC Pilot Jim, 30 September 2014 - 11:25 PM.

[photohc]

In order to accurately measure the drop in voltage due to wire size, you need to have a load connected that is drawing current. If you simply measure the voltage at the solar panel and then at the end of the attached wire with no current being drawn, you will only get the same reading. The voltage reading going to the battery after the controller is the voltage determined by the controller to be the needed charge voltage. 

To determine the voltage drop due to the wiring, measure at the panel, then at the entry point into the controller, as the panel is feeding current into the controller. The difference should be the loss due to wire size. Harv