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Flexible panels direct mount to the roof.


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#41 steve whiteside

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Posted 20 March 2021 - 12:42 AM

Gents, 

Thanks for your help on configuring my system.  Ive got it in and it is working.  I used 4 ea 100watt NewPowa flexible panels that I bought off of amazon.  I bought two of the Lion Energy 1300whr batteries from Costco.  I directly mounted the panels to my roof.  I know that there were plenty of opinions from everyone but at the end of the day I want less wind drag.  Also, when I use my racks I want them for my surfboard.    The rest of the time I want no racks.  Today was full sun in San Diego.  I woke up and the sun was barely over the horizon.  I had about 32 watts flowing.  By noon it was at 230 watts and at 3pm it was 190 watts.  5pm it was at 70watts.  The air temps were typical for this time of year. 45F when I woke up and 70F through the hottest part of the day.

 

So, anyway Im pretty happy and I like how it is pumping power with no action on my part.  Two things I wish were better.  1) the Victron battery monitor that was recommended is having a tough time staying in the hole I cut.  I think I mounted the plastic mount correctly but the gauge keeps popping out the back, and falling into the cupboard.  2) the wiring on the roof is not that clean.  I have four panels in parallel - all of those wires getting routed around the roof, not crossing any panels, and then going into the single FWC connector makes more of a mess than I like.  I have a small pelican box I considered for a Jbox but still could not get all of the wires routed into that box.  

 

I took ri-f's suggestion and have held off on a DC o DC charger from my truck.  It may be that I have enough solar in my situation that I dont need DC from my truck.  If so I can add that later.  

 

I put installed a 1500 inverter as well as a 500watt inverter so that I can run my 120v appliances as efficiently as I can.  I used my drip coffee maker this morning pulling 1KW and had no issues.  

 

Anyway, thanks again for your help.  

 

Steve


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#42 ntsqd

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Posted 20 March 2021 - 03:01 PM

With our first camper I did it in reverse from you. I got the truck to camper wiring installed first. Then I added the solar. In that camper 100W of solar was enough to stay on top of the batteries in our normal use.

 

After I got the solar installed I pondered if I really needed the truck to camper connection. Then the aging batteries coupled with a low two digits night in the Owens Valley one T-Day weekend took us down far, far lower on charge than I would have liked. It was nice to know that our driving the next day brought those batteries back up. I still ended up replacing them after that trip, but at least we had camper battery for the rest of the trip.

 

So, for the sake of redundancy I would suggest that you install the DC-DC converter or some form of alternator charging ability. You won't know that you need it until after when you needed it to be there. Plan on high amps because when you do need that function it will be in the form of bulk charging.


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#43 ri-f

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Posted 20 March 2021 - 05:45 PM

Hi Steve, congratulations on your new solar farm. I know you had a lot of tradeoffs to consider when configuring your solar array. Some of the issues you are describing are probably directly related to your tradeoffs. One example is the clutter of wires running on your roof. This in part is a result of parallel wiring 4 panels in a relatively limited area of your roof. And since your panels aren't off the roof, on a frame, you have eliminated the possibility of running some of the wires under the panels.

I do think that parallel wiring is preferable for situations where partial shading of some of your panels and not others will still give you some output, but series wiring will reduce some of your wire clutter with 4 panels, and it will reduce some of your efficiency losses through the 10 AWG wire that is probably running from your roof to your solar controller. With your panels in parallel you are running, potentially, 24 amps of current through 10 AWG over a long run (maybe 25 feet ?) With 10AWG wire you're almost maxed out on safe maximum current (about 30 amps). In a series configuration, your current through the wire would be reduced to perhaps 5-6 amps and your efficiency would likely increase a few percent. If you had two panels on your roof I would say parallel wiring would be ideal, but 4 panels at 6 amps each is really on the edge. With series wiring your excess increased voltage (maybe 80 volts?) would be optimized and converted to current by your MPPT controller - I'm thinking a Victron 100/30 MPPT controller would handle that load well.

As far as the Victron meter falling out of its mount and into the cabinet: Did you unscrew the plastic sleeve on the back of the meter before you measured and cut out the hole? That sleeve gets screwed onto the threads once the meter is mounted and locks the meter in place. You might have cut the hole too big if you didn't account for that sleeve thickness. In which case, you need to install a new façade over the hole you cut and try again. Or you could hot glue gun (wax) the meter in place from the back side to prevent the meter from falling out.

On DC to DC charger: Like ntsqd said, it's good to have an alternative charge method when you're not in ideal solar conditions. But of course you can always do that later. With 400W of solar, in San Diego, obviously, there's no rush.

Rich


 

 


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#44 steve whiteside

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Posted 20 March 2021 - 09:19 PM

Oh my gosh Rich you are right that gauge has a nut on the back!  I noticed it rotated but I thought it was ... not sure what I thought it was- but it never occurred to me it was a nut!  Yes, I can make a piece of trim and mount the gauge to that.  Im going to leave the wiring as -is for now.  I get your point abut in series but im happy enough with the watts.  Also I have a 4" lift and running 35in tires.  So, unless I climb up on something I don't see the roof.  ;-). Steve

Hi Steve, congratulations on your new solar farm. I know you had a lot of tradeoffs to consider when configuring your solar array. Some of the issues you are describing are probably directly related to your tradeoffs. One example is the clutter of wires running on your roof. This in part is a result of parallel wiring 4 panels in a relatively limited area of your roof. And since your panels aren't off the roof, on a frame, you have eliminated the possibility of running some of the wires under the panels.

I do think that parallel wiring is preferable for situations where partial shading of some of your panels and not others will still give you some output, but series wiring will reduce some of your wire clutter with 4 panels, and it will reduce some of your efficiency losses through the 10 AWG wire that is probably running from your roof to your solar controller. With your panels in parallel you are running, potentially, 24 amps of current through 10 AWG over a long run (maybe 25 feet ?) With 10AWG wire you're almost maxed out on safe maximum current (about 30 amps). In a series configuration, your current through the wire would be reduced to perhaps 5-6 amps and your efficiency would likely increase a few percent. If you had two panels on your roof I would say parallel wiring would be ideal, but 4 panels at 6 amps each is really on the edge. With series wiring your excess increased voltage (maybe 80 volts?) would be optimized and converted to current by your MPPT controller - I'm thinking a Victron 100/30 MPPT controller would handle that load well.

As far as the Victron meter falling out of its mount and into the cabinet: Did you unscrew the plastic sleeve on the back of the meter before you measured and cut out the hole? That sleeve gets screwed onto the threads once the meter is mounted and locks the meter in place. You might have cut the hole too big if you didn't account for that sleeve thickness. In which case, you need to install a new façade over the hole you cut and try again. Or you could hot glue gun (wax) the meter in place from the back side to prevent the meter from falling out.

On DC to DC charger: Like ntsqd said, it's good to have an alternative charge method when you're not in ideal solar conditions. But of course you can always do that later. With 400W of solar, in San Diego, obviously, there's no rush.

Rich


 


Edited by steve whiteside, 22 March 2021 - 12:44 AM.

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