Solar panel overkill?

Almot wrote:

BFL13 wrote:
Ok, I define that much solar {10-15 AH} as peanuts and so call that no solar.

This can be anywhere from 5 to 20 minutes extra generator run, depending on SOC. They want to cut down on genny run, so...

BFL13 wrote:
I am just thinking, without knowing anything about the OP except what he has posted, that some caution is in order here. Maybe getting ahead of himself and will regret nailing down a bunch of solar on that RV when he will then get a different RV for retirement anyway

If they plan to sell it within 2 years, I would not install anything. If they don't sell it for at least 5 years, it will be 14+ years old, and then solar on roof either won't matter or will add the value. Engine condition and mileage will become more important then. Also, they mentioned using it for traveling to their work places and parking close to residencies, so messing with a portable system every time may not be practical. I agree that installing it permanent or portable is a personal choice.

If for some reason I did sell the rig I would take all the solar with me and patch the mounting holes. Keep in mind that with the tax deductions I will be paying about 25-30% less for the system (15% self employment tax + 12-15% income tax savings). As far as making one portable - knowing myself like I do if I don't do both now I probably won't add in the future. If I were to plan ahead for the future I already have to have heavier wire and a larger charge controller and don't see the point in worrying about 4-6 extra holes in the roof and an extra hour or so time.
I want to thank everybody for their very helpful feedback. Still have a few questions though.
1. Should I mount these larger panels with 4 or 6 mounting points? Would rather do 4 if the panel will support its own weight and will not tear through the roof. Plan to make them tilt for roof access.
2. I am thinking on using molly bolts or toggle bolts to lessen the chance of pullout from the roof. Also thinking of making brackets out of 1/4" X 2 1/2" aluminum angle cut into opposing L brackets. Is there a reason to use stainless steel bolts mounting to the roof since I am going to cover everything with Dicor? I would use stainless bolts and nuts above the roof mounts however I am a little worried about galvanic corrosion having the stainless touching the aluminum.
Again thanks for all of your help, Jeff.

BFL13 wrote:
Ok, I define that much solar {10-15 AH} as peanuts and so call that no solar.

This can be anywhere from 5 to 20 minutes extra generator run, depending on SOC. They want to cut down on genny run, so...

BFL13 wrote:
I am just thinking, without knowing anything about the OP except what he has posted, that some caution is in order here. Maybe getting ahead of himself and will regret nailing down a bunch of solar on that RV when he will then get a different RV for retirement anyway

If they plan to sell it within 2 years, I would not install anything. If they don't sell it for at least 5 years, it will be 14+ years old, and then solar on roof either won't matter or will add the value. Engine condition and mileage will become more important then. Also, they mentioned using it for traveling to their work places and parking close to residencies, so messing with a portable system every time may not be practical. I agree that installing it permanent or portable is a personal choice.

Almot wrote:

BFL13 wrote:
Overcast you get no solar, no matter if you have twice the panels.

10-15 AH a day from 450W not possible?

Ok, I define that much solar as peanuts and so call that no solar. YMMV.

I am just thinking, without knowing anything about the OP except what he has posted, that some caution is in order here. Maybe getting ahead of himself and will regret nailing down a bunch of solar on that RV when he will then get a different RV for retirement anyway.

I don't know--"just sayin"

BFL13 wrote:
Overcast you get no solar, no matter if you have twice the panels.

10-15 AH a day from 450W not possible?

There is no overkill with solar. Get as much as you can, as long as they don't shade each other and are not shaded - too much - by the A/C unit and other things on the roof. I would not tilt. Climbing the roof every time is not fun, and the chances that you'll be able to park in the right direction are 50/50.

Make sure the controller has enough input voltage limit to handle series connection if you chose to do so. Ecoworthy does not. I would stick to known brands of controllers, I haven't heard of Tracer brand. 30A Rogue is right at the limit for 450W, should be adequate considering that clipping is only important when your batteries demand that much current, and often they don't. With 40-45 controller you will - probably - get a few more amp-hours a day, not much.

Overcast you get no solar, no matter if you have twice the panels.

Mixed sun and cloud days like we often get, you get more AH by having twice the panels for when they get some sun.

One panel that can be pointed at the sun when it is out can have the same sort of benefit. "Depends" whether one tracking will do as well as two not tracking.

Tilted up pointed South is always better whether one or two panels if not tracking.

Although not being in the "PNW" (being in Canada) we do get similar weather. From my experience so far, trying various schemes, we get almost as much with one tracking as two not tracking.

So it might be cost effective, considering the amount of time in those PNW conditions, to make your one panel portable and forget the second panel. That would cover all the bases until you know for sure what the future requirements are.

I have two sixers and 440w, 300w via MPPT, 140w via PWM. You're smart to consider the PNW weather and Latitude, but results will be good across the board. Go with the two panels and you'll well appreciate the less than ideal harvest conditions potential afforded. With a PM I'm happy to provide any non-theoretical specifics.

Best Regards,

3 tons

Go for the two panels. You may have days with just one or two hours sun where you want the max charge rate.

Consider a battery monitor for about $160. Check the SOC, weather app and you've got the information for any gen run time. And easy to move to a future rig.

With 60% SOC you have 230*40%=92AH. 470W/14V=34A ideal and you’ll probably get half. So 17A*5 hrs = 85AH. Almost there but DW want more TV time. There are a lot of variables.

Some days you’ll be OK and others you can run the gen on the cold mornings. Sounds like 2 panels should work.