Community Forums

Orionfe · 03-08-2017, 08:27 PM

Hi All,
I'd like to bring up the good old solar system subject as I am trying to get smart on this prior to purchasing. I'd like to have the 500W capability, but not sure if there is room for 3 panels.
Any particular brands to look at / shy away from
I'd like the ability to power the whole coach off the solar alone if ever necessary

Any / all comments welcome...thanks in advance

Bill

Kiawah · 03-08-2017, 08:39 PM

Go Power! Solar Sizing Guide | Go Power!

To do some initial sizing

billdreamlv · 03-08-2017, 09:56 PM

Stick the money in the best panels you can buy and the at highest wattage. Here is a 270 watt per panel unit for $170.

270 watt Solar Panel Peimar OS270P

And this:

https://www.gogreensolar.com/product...tt-solar-panel

The real estate is sparse on the roof and that is why you should purchase the high wattage panels.

The rest of the stuff just needs to be sized right. I have 1060 watts and it is wonderful. I use a Midnite solar 150 charge controller. Because the panels are flat on the roof, you will lose quite a bit of solar. So, go big. If you look at some of the posts you will read where most want to increase their solar panel wattage. Mount your charge controller where you get plenty of air. It does produces a lot of heat. When I have mine going, I open the door to the inverter bay where the charge controller is mounted.

Here is a link that might help.

http://www.irv2.com/forums/f106/adde...ls-306791.html

Orionfe · 03-08-2017, 10:23 PM

What do you look for in panel quality. Is one better than the other IE mono versus poly. I don't mind paying extra for good quality without getting ripped off.
There is a lot of junk out there.
I hate doing things twice

vsheetz · 03-09-2017, 07:28 AM

Differing ways to design with much based on availability of unshaded roof space. Else lift the panels with a racking system over roof obstructions. I did not want to loft and have a very busy roof mostly down the center. I opted to go with several narrow 100w panels arranged down either side of the roof. 1500w in three strings with #10 wire down from the roof to a combiner box / breaker box / disconnect point near the batteries. The controller is a Midnight Solar Classic 150. A 150a breaker in the battery compartment provides for disconnect there.

I used Renogy brand panels. One of the few narrow 100w panels available. Reasonably priced and can be bought directly or via Amazon.

Old Scout · 03-09-2017, 07:58 AM

As mentioned--you really have to do your homework. For example: one post above shows 270watt panels for $175 [MINIMUM order: 27 panels]--oops! Most panels this size are in the range of $300-400. I am a rank beginner having added 400 watts [4-100 watts Renogy] to 100 watts of OEM panels. Basic rule of thumb--go big or reduce expectations. Basic issue for me is working with what I call a "120v mentality" in a 12v solar world--meaning the "conversion" from 12v solar output to 120v consumption is startling to say the least. If you have a residential fridge, plasma TV, propane heat or hydrohot, and other parasitic draws--then "powering the whole coach" is a major challenge. IMHO opinion: 600-1000 watts is the minimum "investment" and you still have to look at cutting back on your "120v lifestyle."

billdreamlv · 03-09-2017, 04:12 PM

Quote:

Originally Posted by Old Scout

As mentioned--you really have to do your homework. For example: one post above shows 270watt panels for $175 [MINIMUM order: 27 panels]--oops! Most panels this size are in the range of $300-400. I am a rank beginner having added 400 watts [4-100 watts Renogy] to 100 watts of OEM panels. Basic rule of thumb--go big or reduce expectations. Basic issue for me is working with what I call a "120v mentality" in a 12v solar world--meaning the "conversion" from 12v solar output to 120v consumption is startling to say the least. If you have a residential fridge, plasma TV, propane heat or hydrohot, and other parasitic draws--then "powering the whole coach" is a major challenge. IMHO opinion: 600-1000 watts is the minimum "investment" and you still have to look at cutting back on your "120v lifestyle."

Oldscout, I agree with your assessment of the panels. I didn't mean to mislead anyone. It was the option of high wattage panels available in the marketplace as opposed to older panels that are less wattage for the same price. Monocrystoline panels are better than polycrystoline panels as far as effeciency and heat.

roaming · 03-09-2017, 04:38 PM

Excellent info here, especially Bill's point about making sure your controller is well vented. There are a few manufacturers of narrow panels now, we just put 4 Grape Solar 180w panels feeding a Morningstar MPPT-60 on our 2011 40QTH, and there's plenty of room on the roof for more.

When going solar, more is always better, and always upsize everything - your controller(s), your wiring, your batteries. 4 gauge welding wire (flexible) from the combiner box on the roof down to your controller, and at least that from the controller to the battery bank.

We had 10 panels feeding 2 MPPT-60s into 10 house batteries on our 42' Travel Supreme Select, and with a Norcold 12v/propane fridge were able to power the entire coach off-grid for a couple years, except for running A/C units. Our generator hours went up 6 a year from running it once a month for 30 minutes to keep it functional. Since we have a residential fridge now and only 720w we'll be happy to keep the fridge going and some minor other loads.

You can tilt your panels to take the most advantage of the sun based on your latitude, I made our mounts out of 3x3 aluminum angle (4x3 on the new coach), and used some 1" aluminum bar stock to make the tilt bars. I looked at the nice mounts by AM Solar but the price made me cringe. If you're handy, make your own and save a bundle.

J&C

Orionfe · 03-09-2017, 08:46 PM

Thanks for all the great input.
I'm still kinda concerned about build quality.
For example...I found an astroenergy 305W panel for 255.00 ea.
OR I could 300-400.00 for a 100W panel all day long both for mono panels
Somebody is out of whack and not sure who.
I question build quality due to the obvious vibration issues during travel where a house system wont go through that

Orionfe · 03-09-2017, 08:51 PM

Crap, sorry but the astroenergy ones are polycrystalline...sorry for my error and lack of attention to detail

billdreamlv · 03-09-2017, 10:39 PM

Bill, that's precisely my point. The older 100 watt panels cost just as much as the new 305 watt panels that are monocrystalline. If you hunt around you can find more watts for Less money. All you need to do is look for monocrystalline panels and you can find panels that are 3 to 400 watts at a very reasonable price. The solar panels that you find at retail outlets such as Amazon and Home Depot are less wattage and more money. But they do the same thing as the panels that you buy from solar warehouses. Look at it in price per watts and you can get a good deal.

jimbo2013 · 03-10-2017, 04:37 AM

panels are classified in three tiers.

Buy only tier one.

google it

Orionfe · 03-11-2017, 11:46 PM

I wanted to verify some info on this panel issue. I have read a couple of places that 24V (OCV) panels are not compatable and cannot be used on 12V battery systems. Doesn't the MPPT controller step the voltage down to the required (usually 14-14.5 VDC) charge voltage for the batts.
I'm looking at panels that are between 255 and 305W all of which are 24VDC OCV output.

Thanks all

twinboat · 03-12-2017, 01:24 AM

Quote:

Originally Posted by Orionfe

I wanted to verify some info on this panel issue. I have read a couple of places that 24V (OCV) panels are not compatable and cannot be used on 12V battery systems. Doesn't the MPPT controller step the voltage down to the required (usually 14-14.5 VDC) charge voltage for the batts.
I'm looking at panels that are between 255 and 305W all of which are 24VDC OCV output.

Thanks all

You are correct. That's one of the benefits of MPPT controllers. They cut the voltage while increasing the amperage.

I run 3, 36 volt panels, to my MPPT controller, all in series. It takes the 100 volts and converts it to 13.4 to 14.6 charging volts.

Higher voltage panels allow you to keep the wire gauge from the panels to the controller smaller. You still need the heavy wire to the batteries, but that's why you keep the controller close to the batteries.