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Open Roads Forum  >  Tech Issues

 > Calling on Solar Techies

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pianotuna

Regina, SK, Canada

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Posted: 01/25/21 05:57pm Link  |  Quote  |  Print  |  Notify Moderator

1L243 wrote:

Am I to assume that the concerns with the WFCO 8900 converter charging or not charging the batteries correctly only a issue when I am plugged into shore power and nothing to do with Solar correct?

When charging the batteries on Solar through the Solar charger/controller with built in safe guards there should be no issue correct?

PS I purchased the Renogy 2000w Pure Sine Wave Inverter


Solar has nada to do with a converter. They do play well together in my case, and may do the same for you.

Since you have your inverter--forget what I said about an inverter/charger.


Regards, Don
My ride is a 28 foot Class C, 256 watts solar, soon to have SiO2 batteries, 3000 watt Magnum hybrid inverter, Sola Basic Autoformer, Microair Easy Start.

pianotuna

Regina, SK, Canada

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Posted: 01/25/21 06:05pm Link  |  Quote  |  Print  |  Notify Moderator

Location of the charge controller might be because of the size of wire the controller can accommodate.

I love the Morningstar Tristar charge controller because it has battery voltage sense wires.

I don't use a battery monitor much at all. So all I go by is voltage. I don't like shunts.

I do monitor wattage @ 120 volts ac.

Since I'll be going to SiO2 batteries state of charge really doesn't matter much--and as I'm now a weekend warrior the solar charging will return the batteries to fully charged between trips.

* This post was edited 01/25/21 06:22pm by pianotuna *

StirCrazy

Kamloops, BC, Canada

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Posted: 01/26/21 07:35am Link  |  Quote  |  Print  |  Notify Moderator

1L243 wrote:

My battery monitor is not that sophisticated. When the lights don't come on it will tell you the batteries are dead.

I am in the market for a good battery monitor. Not sure what information the solar controller is going to provide but I would like to know things like amp/watts coming and going current battery status power level.


here is a good one, it is pretty much a copy of the Victron with out the bluetooth and one other reading but it shows percentage, curent in or out, ah remaining and voltage. I have this one on my Camper and it is way cheeper than the Victron.

Monitor


Steve


2014 F350 6.7 Platinum
2016 Cougar 330RBK

1L243

Oregon

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Posted: 01/26/21 07:33pm Link  |  Quote  |  Print  |  Notify Moderator

After talking to tech support they said that the Charger Controller needs to be within 5 feet of the battery.

The contact was done by text so there was no explanation. It probably has to do with volt drop coming out of the battery side of the Charge Controller.

This brings up the distance between the panels and the Charge Controller. Since I have to put the Charger Controller close to the battery the distance from panel to Charge Controller will be approximately 35 feet. I am using 10ga wire for solar.

I would be interested on hearing from anyone that has installed their own system on a RV and what kind of distances from panel to Charge Controller were encountered. What size wire was used.

I have watched several DIY RV Solar installation videos and nobody discusses voltage drop between panels and Charge Controller.

I used a low voltage calculator and put in my perimeters and it's actually not great. But I am not sure those calculators are geared for low voltage that are present in solar systems.

I will have 5x100 watt panels wired Parallel Using a 40a PWM charge Controller.

Panel max power point 18.0v at 5.56 amps

Waiting to hear back from Tech support.


2017 Coleman 300tq by Dutchman Toy Hauler. 34.5 feet long and under 10k Gross. 1999 Ford F250 2WD 7.3 4R100 DP Tuner, S&B Cold Air Intake, Gauges, 6.0 Trans Cooler, Air Bags.


time2roll

Southern California

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Posted: 01/26/21 07:49pm Link  |  Quote  |  Print  |  Notify Moderator

My 3x 225w panels are in series to produce about 7.5 amps at 90 volts. The loop is about 60' using a #10 wire MC4 extension cable. I cut the extension cable in half with MC4 to the panels and the cut ends to the controller.

Controller is about 2' from the battery with #4 wire. Pictures in signature.

Amazon has MC4 cables with #8 wire if that helps.


2001 F150 SuperCrew
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BFL13

Victoria, BC

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Posted: 01/26/21 08:47pm Link  |  Quote  |  Print  |  Notify Moderator

You don't use max power point with PWM so forget that. You don't care much about voltage drop on the panel to controller wires with PWM either. Just what amps you get. Panel voltage will be near battery voltage 12-14.5ish.

You need to reduce voltage drop controller to battery so the controller set to 14.6 (say) will not stop charging at 14.2 or whatever, thinking the batts are 14.6 when they are really 14.2. That's why the 5 ft. Or use fatter wire if farther away. Fuse to the wire gauge if fatter wire.

Five 100w at 6 amps each is 30 amps, so #10 panel to controller should be ok even at 35 ft one way, but I would use #8 if there is a choice. Most of the day you don't get full amps like you do at noon, so it is not as big a deal as it might seem using noon numbers.


1. 1991 Oakland 28DB Class C
on Ford E350-460-7.5 Gas EFI
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2. 1991 Bighorn 9.5ft Truck Camper on 2003 Chev 2500HD 6.0 Gas
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pianotuna

Regina, SK, Canada

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Posted: 01/26/21 09:06pm Link  |  Quote  |  Print  |  Notify Moderator

1L243,

I have MPPT, and only 256 watts of panels. I used #8 wire for a 4 foot run to the battery bank(s). My charge controller is temperature compensated and I've seen 15.2 volts. I get about 17 amps of output if the batteries are hungry, or I turn on a large load.

I'd encourage you to have a catastrophic failure fuse extremely close to the battery. Mine are on the battery posts (I have twin banks).

With 30 amps I would go for #4 or #6 wire from the controller to the battery bank. #10 is not going to help.

My overall voltage drop from panels to controller is less than 1%. The nominal input voltage to the controller is 33.

* This post was edited 01/26/21 10:31pm by pianotuna *

Vintage465

Prunedale CA.

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Posted: 01/26/21 09:12pm Link  |  Quote  |  Print  |  Notify Moderator

I guess the only thing I'd add is to check ALL, that's ALL solar panel foot print size vs watts. I've found that most solar panels from 150w to 200w seem to be within and inch either way of the same size. If I knew more about solar when I got mine(from the dealer!)I'd have 600w of solar right now instead of 450w with the same amount real estate usage on the roof.


V-465
2013 GMC 2500HD Duramax Denali. 2015 CreekSide 20fq w/450 watts solar and 465 amp/hour of batteries. Retiring in 2021, then look-out road, here we come!

1L243

Oregon

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Posted: 01/26/21 09:12pm Link  |  Quote  |  Print  |  Notify Moderator

If I was to keep all my perameters the same ie 10ga wire size and distance from panels to Charge controller 35 feet but change to a MPPT 40 amp charge controller which would allow me to wire the panels in series how would that change my situation?

thanks.

BFL13

Victoria, BC

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Posted: 01/26/21 09:42pm Link  |  Quote  |  Print  |  Notify Moderator

Your total Voc in series would be 5 times 23( see specs for exact Voc) or 115v which would fry a typical controller rated at 100Voc input. Some claim 150v. Read the fine print too. One that says 100 says it is really 90 eg.

When you go over three in series (a "string") some set-ups go to series/parallel to keep the voltage down.

The MPPT's controller to battery wiring is still for 12v, so no change there for wire gauge and distance.

Mostly it is not worth the theoretical gains to go MPPT in series or in parallel with five 100w panels. I have tried all different ways with three 100s between series and parallel with MPPT and parallel with PWM and got pretty much the same amps to the battery.

IMO just go with the easiest way to do it. After the first summer, if you think then it would be worth it, you can switch the wiring around to suit. (So be sure you can get at those wiring connections as mentioned before)

EDIT--even with same amps to the battery, you might get more AH in the day with MPPT due to more in the shoulder hours. BUT--you don't know how many AH you will usually get in a day where and when you camp.

You might well find that you get more AH then you use with the simple PWM set-up, so even though you could get more with an MPPT set-up, that would be just more AH not being used. So IMO do one summer first, then see. For what you have said you will be using, IMO based on what we see, you will be ok.

* This post was edited 01/26/21 09:52pm by BFL13 *

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