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MrWizard

Traveling

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Posted: 08/12/20 05:56pm Link  |  Quote  |  Print  |  Notify Moderator

Those are 48v panels, what are you using for a charge controller ?

GravelRider wrote:

I called a local solar installation business, and they will sell me two 400 watt panels for $500 total out-the-door for both panels. Sounds like a great deal to me and I won't have to deal with shipping.

These panels:
https://www.solarelectricsupply.com/q-cells-q-peak-duo-l-g7-2-400w-solar-panel



* This post was edited 08/12/20 06:09pm by MrWizard *


I can explain it to you.
But I Can Not understand it for you !

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GravelRider

Pennsylvania

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Posted: 08/12/20 07:19pm Link  |  Quote  |  Print  |  Notify Moderator

CA Traveler wrote:

If those mounts are Z mounts pitch them. Instead use 2x al angle connected with a bolt like a Z and the panels are much easier to remove when needed.

A number of posters have used only 3M VHB tape to secure panels. I used VHB tape, screws and sealed with Dicor.


I don't know what you mean by al angle.

CA Traveler

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Posted: 08/12/20 07:58pm Link  |  Quote  |  Print  |  Notify Moderator

Aluminum angle, HD etc sell it.


2009 Holiday Rambler 42' Scepter with ISL 400 Cummins
750 Watts Solar Morningstar MPPT 60 Controller
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Bob


StirCrazy

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Posted: 08/12/20 11:03pm Link  |  Quote  |  Print  |  Notify Moderator

CA Traveler wrote:

If those mounts are Z mounts pitch them. Instead use 2x al angle connected with a bolt like a Z and the panels are much easier to remove when needed.

A number of posters have used only 3M VHB tape to secure panels. I used VHB tape, screws and sealed with Dicor.


I like that idea, I just picked up a 325 watt 120 split cell panel to put on my truck caper with an alumium roof. only thing left to arive is the mounting brackets.

did you put the alumin angle on the inside of the panel skirt and tap it for the bolt or the out side and use a nut and bolt?

Steve


2014 F350 6.7 Platinum
2016 Cougar 330RBK

GravelRider

Pennsylvania

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Posted: 08/13/20 06:25am Link  |  Quote  |  Print  |  Notify Moderator

MrWizard wrote:

Those are 48v panels, what are you using for a charge controller ?

GravelRider wrote:

I called a local solar installation business, and they will sell me two 400 watt panels for $500 total out-the-door for both panels. Sounds like a great deal to me and I won't have to deal with shipping.

These panels:
https://www.solarelectricsupply.com/q-cells-q-peak-duo-l-g7-2-400w-solar-panel



I'll be using a 60 amp MPPT controller. I haven't picked a specific brand yet.

GravelRider

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Posted: 08/13/20 06:35am Link  |  Quote  |  Print  |  Notify Moderator

CA Traveler wrote:

Aluminum angle, HD etc sell it.


Oh okay! So obvious now. Lol. Thanks for the recommendation.

GravelRider

Pennsylvania

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Posted: 08/13/20 06:42am Link  |  Quote  |  Print  |  Notify Moderator

And by the way, these panels have a short circuit current of 10.19 amps. I'm assuming a 10 amp breaker for each panel before the parallel connection would be appropriate, and then a 20 amp after the parallel connection to the controller, and then a 60 amp from the controller to the battery. Or will I run into issues with the breaker tripping because of that additional 0.19 amps (and 0.38 amps after the parallel connection). To be honest, I don't know how close the current ever gets to the short circuit current with regular use. However, I would assume it does not get close, as normal optimal operating current would be around 8 amps (400/48).

CA Traveler

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Posted: 08/13/20 07:46am Link  |  Quote  |  Print  |  Notify Moderator

For 2 parallel panels no breaker required. For 3 it's a good idea. Usually fuses are used in the combiner box on the roof, not likely they will ever blow. Use 15A as 10A is to close to the panel or whatever the panel specs say. There are effects such as cloud edge that can cause max current.

CA Traveler

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Posted: 08/13/20 07:53am Link  |  Quote  |  Print  |  Notify Moderator

BTW MPPT controllers usually switch to PWM mode (uses Isc - I short circuit) for lower charge rates which is another reason for a larger fuse, might even reach full amps under the right conditions, probably for a limited time.

I have a switch, no fuses on my 3x serial panels. And a 60A switchable CB, Blue Seas I think - but independent unit that isn't installed in a breaker box. No need for a breaker box. PLUS DC switching under load is much more intense on contact arcing than AC. DC breaker boxes and CBs are expensive and not found in hardware stores.

GravelRider

Pennsylvania

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Posted: 08/13/20 08:50am Link  |  Quote  |  Print  |  Notify Moderator

CA Traveler wrote:

For 2 parallel panels no breaker required. For 3 it's a good idea. Usually fuses are used in the combiner box on the roof, not likely they will ever blow. Use 15A as 10A is to close to the panel or whatever the panel specs say. There are effects such as cloud edge that can cause max current.


Okay, good to know. I wasn't sure how close the current got to that. Thanks. I'll use 15 amp fuses. I wanted to do breakers, but I couldn't find anything rated for 48 volts that wasn't for a breaker box, so I'll just use two inline blade type fuses.

I'm not actually going to use a combiner box. I am planning on using a stud junction block for the negative wires and then I am going to just mount both 10 AWG wires coming from the panels directly to the 30 amp circuit breaker (rather than 20 amps, as per your post above). I'm assuming this won't be an issue, right?

And I'm going to do the parallel junction in my forward basement storage area where the controller will be. I'll have to run more wires down, which will be a pain, but I figure this will maximize wire length in the lower current wires and minimize it as the current increases.

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