Solar Options

Topic: Solar Options (Read 798 times) previous topic - next topic

Solar Options

April 16, 2022, 12:09:49 pm

I am researching solar installations. This will be my first jab at this and trying to sort through all the different manufacturers is somewhat mind numbing. So I thought I'd come here for some expert advice. What I've seen so far is rigid or flexible on solar panels. I like the flexible due to no roof penetrations but my mind is open to either. I need to get on the roof and measure the area I have to work with. Brand and amp ratings of charge controllers. I like the idea of having Bluetooth. As far as amp rating I'm clueless.
I have 600 amps of AGM on the house bank and a 3000 watt Xantrex inverter. I'm not really looking to be able to totally run off of solar. Although that would be nice. Just trying to minimize time spent running the generator when off grid. In the brochure for my '08 it listed an option for a solar package. I'm hoping that means a chase for wiring. I'm going to call Foretravel on this. So I'm interested in what's worked for different folks and what you would do over again and what you'd change.
Thanks in Advance,
Robert

Re: Solar Options

Reply #1 – April 16, 2022, 02:15:19 pm

You can learn a lot from previous posts. I definitely would go with standard panels. Go to AM solar and watch the video on installing panels with vHB tape. It ready works on our roofs.

Re: Solar Options

Reply #2 – April 16, 2022, 03:18:43 pm

After Paul Smith, ours is the oldest solar installation on the forum. Flex panels don't have a good reputation. I like the commercial panels with the substantial aluminum edges. We mostly dry camp and are frequently pushing through branches, etc. Most all panels are good. China leads the field here but excellent panels made here, Canada, Germany, etc. Check the height and width of panels and then make a cardboard copy to try on your roof. The latest panels have the most watts for the size. Shorter panels may fit in tight locations. Mono vs poly panes. Not much difference in the real world. We screwed into the roof like most commercial shops do. There are already a couple of hundred screws already in the roof so if sealed properly, a few more are not a problem. Lots of good controllers on the market today. We went with the top controller in 2008. It's still up at the top today. Made in the USA with long warranty and quick turn around if any problems. Amazon.com : MidNite Solar CLASSIC 150 MPPT Charge Controller, 150 Operating... Reviews of controllers at: The 10 Best Solar Charge Controllers (+ How to Choose One) - Solar Smarts See my old installation posts along with material list and sources.

13 plus years later, everything is working as well as when installed with zero problems. Have not used the generator for years except for emergency power for the many PG&E power outages.

Pierce

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Re: Solar Options

Reply #3 – April 16, 2022, 04:15:18 pm

My rig had a solar installation when I bought it. Two panels on the roof, 26"W x 58"L. They are mounted inline on the street side, from the shower skylight dome back. They sit next to the rear AC unit. They had a cheezy controller that failed within a few months of me owning it, and was overcharging the house batteries. I replaced that POS with a Victron MPPT 100/30 controller. It will accept up to 100V, 30amps.

My existing panels were wired in parallel. Their open voltage is about 18V. Wired in parallel, they would put out about 18-19V and 10amps in bulk charging mode. (19V*10A = 190w)

While in Quartzite for the RV show, I had Offthegridrvs rewire the panels with upgraded 6ga wire. They also set them up in series, so now the panels put out about 30V and 6-7 amps while in bulk charging mode (30V*7A=210w). Lower amperage means less heat in the cable. The only downside to wiring in series that I'm aware of is that if one panel is shaded, it's lower output pulls the output from the whole bank down to that level. In parallel, each panel puts out whatever it can and that amount is received by the controller.

This also means that if you have different sized panels, the lowest size/output panel will limit the entire chain if wired in series; however, you can wire two smaller panels in parallel to make more output and wire those in series with larger panels. Lots of options is what I'm getting at.

I'm not sure what the output rating of my panels are, but the most I've seen is about 210w for the pair. Maybe they are 120w panels. Regardless, I think I'm going to have Offthegrirvs remove and replace with 4 180w or so panels of the same size, which should double to triple the output I have now. That should be enough to keep up with what the coach uses sitting static (residential fridge pulls a bit). I think I can move the forward most panel forward to the shower skylight, then put three panels sideways behind the AC unit to get four on the back area.

Re: Solar Options

Reply #4 – April 16, 2022, 05:04:29 pm

Keith,

Looks as if you have lots of room for more panels. Panels are cheap, cheap, cheap and have lots of watts today. If I replaced our old panels with new ones, the potential wattage would go from 1140 to 1440 or more without increasing the number or area of the panels. I wired ours in a series/parallel arrangement so for our 36 volt panels, we have 72 volts coming down to the controller. I could have wired in all series but would have had 144 volts coming down to the controller. Higher voltage can shock easier with a greater chance of injury. Plus, 144 volts would have been quite a bit more on a cold morning, easily exceeding the 150 volt rating of the controller. Solar panel ratings are at 25°C/77°F, so when they get hot, the rating is less and when it's freezing, the wattage/voltage is more.

A lot of people use Victron contollers. Good reviews with the small size a real plus. Cons are small connectors for the wires and no fan. With small connectors, you have to make sure to run the battery wires a very short distance to a bus where the large cable then goes to the batteries. Otherwise, the loss is higher than the 3% for the entire solar wiring that is the industry number to shoot for.

Pierce

Have not had a problem with shading. We shut all electrics down when we go to sleep. After a night of TV, etc, there is still plenty to use the microwave and latte maker in the morning. Bats are full well before noon. We have a 50" TV, LED lighting and run an amp for the sound system when the TV is on. Fridge is aNorcold RV propane/110V.

Tilting panels will raise the efficiency but greatly increase the chance of a long term injury or fatal fall if you go up there. If you have lots of watts, it's overkill anyway.

Re: Solar Options

Reply #5 – April 16, 2022, 05:47:57 pm

I had 150 watts on my 1981 Foretravel and full timed off grid in it for 10 years. Solar was a great investment in 2004 and it's an even better investment today. I have 500 watts on my current coach which I've full timed in for 8 years and would add more panels and amp hours to the battery bank if I was still off grid but I rarely am these days.
I think you want to max out the number of watts you can reasonably put on your roof and get a solar controller that will handle them. You will probably switch out your AGM batteries for lithium at some point and probably the Xantrex 3000 as well. As long as the panels and solar controller are installed to work with what you have, it should be easy to switch batteries and an inverter in the future.
I agree that tilting panels is overkill. I had them on my 1981 Foretravel and mounted my current panels without them.

Re: Solar Options

Reply #6 – April 16, 2022, 06:19:08 pm

Dakota,

Yes, overkill. Plus, tilting so the sun is perpendicular is only good for a brief moment as the earth rotates and the angle changes.

Panel rating is the maximum potential wattage at the standard temperature and exactly perpendicular. Otherwise, it's less. That's why you can never have too many watts up top.

Good to spend a little more for a top controller with plenty of capacity so you don't have to buy a larger model in the future.

Pierce

Re: Solar Options

Reply #7 – April 16, 2022, 06:29:28 pm

The previous owner had bought the system for my coach. It came with 4 270 watt panels
a Magnum Pt !00 controller an a Magnum 2812 inverter. Having solar wasn't one of my
priorities but as it came with the coach I installed them. Now that I have it I am glad I have
it. I ski and I was surprised how well it worked in the winter.

Re: Solar Options

Reply #8 – April 17, 2022, 01:43:42 am

I have 700 Watts on my roof, 2 panels, 350 watts each panel, 1270 x 710 x 30mm, German Panels with 23 % efficiency, $140-00 each, Mono panels,

They are bolted down and 75 MM off the roof in a stainless bracket, Wired in Parallel,
They need air space under the panels to dissipate heat,
I have two 40 Amp Controllers, One for each panel. $57-00 each,
Two 50 amp circuit breakers, One for each controller, Between battery and controllers,
600 amps of AGM's, 3 x 200 amps,
Plus a 75 amp and 900 CCA start battery, Which I can connect to the house bank and solar via a circuit breaker in the battery box,
I am now totally 12 volt thru out my coach, I only free camp,
The AGM's were second hand from an ex govt standby system, Computer back up,
$300-00 each,

The panels came with 20 Amp controllers, But had a melt down soon after installation, Not big enough,
I have the exact same system on my boat as a full time live aboard,
It took 2 hours to put my batterys at 13.4 volts from 12.4 in the morning, 710 amps of lead acid Batterys,
It ran the 90 litre freezer 24/7 and the GPS, anchor lights, Nav lights, cabin lights, Laptop, Etc Etc,

A couple of tips with your solar set up.
Use the heaviest wires possible from panels to batterys,
A 50 amp circuit breaker between Controller and batterys, Instead of a Fuse, Makes it easy to work on the batterys if you need to, and you wont short out your panels,
Run your fridge on gas, As a fridge will flatten you batterys overnight, They are power guzzlers,

Re: Solar Options

Reply #9 – April 17, 2022, 11:55:19 am

Good point about the breakers. While I installed a fusible link at the big bus, I installed breakers between the panels and the controller and also between the controller and main battery bus.

Pierce

Re: Solar Options

Reply #10 – April 17, 2022, 02:33:04 pm

I would say that if you appreciate and value the comments and expertise on this forum , then go with the most popular equipment used on this forum. That way in the future when you have follow up questions or are seeking advise you'll get the maximum input from people. Better to have 30 responses to a question than 3.

Having said that we may switch out our new Magnum 3012 next year for the more commonly used VictronConnect brand charge controller and inverter/charger.
One of those " if I knew then what I know now things".

The Magnum is a great ,quality piece of equipment AND built close to our summer home. But. Not as many user friendly features near as I can tell.

As always DWMYH.

Re: Solar Options

Reply #11 – April 17, 2022, 03:29:37 pm

Any opinions or experience with the Renogy kits?

Amazon.com : Renogy 400 Watts 12 Volts Monocrystalline Solar RV Kit Off-Grid...

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Re: Solar Options

Reply #12 – April 17, 2022, 04:31:11 pm

I have a Renogy Tracer charge controller that's worked flawlessly for 8 years.

Re: Solar Options

Reply #13 – April 17, 2022, 05:16:12 pm

https://www.youtube.com/watch?v=kF_cVEYxj3E
This guy covers most of my questions. He has extensive knowledge and videos .

This is my controller. 60A 100A MPPT Solar Charge Controller Battery Regulator Charger 12V/24V PV...

Re: Solar Options

Reply #14 – April 17, 2022, 05:39:42 pm

Quote from: MarkC – April 17, 2022, 03:29:37 pm

Any opinions or experience with the Renogy kits?

Amazon.com : Renogy 400 Watts 12 Volts Monocrystalline Solar RV Kit Off-Grid...

Thats looks like a good price and has decent specs. I'll have more that that in my 900watt used panel setup . The basic info that I found is to use the MPPT controllers. I bought the largest one that i envision using. Data also seems to indicate that too much controller capacity will also cost a few points of efficiency.

Can we pin this thread to the top someplace . The questions come up often with the same answers I did a search a while ago and struggled to find useful answers.

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Re: Solar Options

Reply #15 – April 17, 2022, 06:59:35 pm

These are the circuit breakers I use, Cheap, Very small and can be put any where.
IP 67, Totally waterproof,
I mainly use them as an On Off switch to work on my systems,
Press the button and the system is off,

Re: Solar Options

Reply #16 – April 17, 2022, 07:04:23 pm

Quote from: MarkC – April 17, 2022, 03:29:37 pm

Any opinions or experience with the Renogy kits?

Easy DIY, system with two or three of these smaller 12 volt panels with rocker mounts with tilt option if nothing else to clean under panels, Victron Bluetooth controller. Plenty of amps for average power consumer if not powering residential fridge.

1- 215 Watt 12 Volt Battery Charger Solar Panel Off Grid RV Boat 215 watt...

Amazon.com: Victron Energy SmartSolar MPPT 100V 30 amp 12/24-Volt Solar...

40mm Rocker Foot Mount Set

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Re: Solar Options

Reply #17 – April 17, 2022, 09:25:57 pm

I thought the video was great. Long term durability is tough to check in any comparison like he did. Lots of good controllers out there without breaking the bank. Inverters are another story. Couple of good videos on YouTube with smoke and fire.

Pierce

Re: Solar Options

Reply #18 – April 18, 2022, 11:13:25 am

Quote from: Mr B3 – April 17, 2022, 06:59:35 pm

These are the circuit breakers I use, Cheap, Very small and can be put any where.
IP 67, Totally waterproof,
I mainly use them as an On Off switch to work on my systems,
Press the button and the system is off,

I looked at similar breakers, but all I found were rated at no more than 48V. With 24V panels in a series/parallel configuration, I can sometimes exceed 90V coming into the controllers. I went with these breakers instead:
https://www.automationdirect.com/adc/shopping/catalog/circuit_protection_-z-_fuses_-z-_disconnects/circuit_breakers_-a-_circuit_protectors/miniature_circuit_breakers_(mcb)/gmcbu-2b-20
They are rated at 125VDC and are inexpensive. A word of warning: I tried some similar breakers from Amazon but they were so cheaply made that the lugs did not tighten enough to hold the wires securely.

Re: Solar Options

Reply #19 – April 18, 2022, 11:19:27 am

Quote from: dbennett9 – April 18, 2022, 11:13:25 am

I looked at similar breakers, but all I found were rated at no more than 48V. With 24V panels in a series/parallel configuration, I can sometimes exceed 90V coming into the controllers. I went with these breakers instead:
https://www.automationdirect.com/adc/shopping/catalog/circuit_protection_-z-_fuses_-z-_disconnects/circuit_breakers_-a-_circuit_protectors/miniature_circuit_breakers_(mcb)/gmcbu-2b-20
They are rated at 125VDC and are inexpensive. A word of warning: I tried some similar breakers from Amazon but they were so cheaply made that the lugs did not tighten enough to hold the wires securely.

Those ones are too big, I started off wanting mine for Battery leads, Which they do work on them very well,
Mine came off Ebay.com

Mine are 48 Volts and 150 Amps, and 50 amps, More than capable of any power the Solar panels will put out,
My panels are 350 Watts each, 12 volt system,

48 Volts and 300 amps are the bigger ones,

Re: Solar Options

Reply #20 – April 18, 2022, 11:54:23 am

Quote from: Res777 – April 16, 2022, 12:09:49 pm

What I've seen so far is rigid or flexible on solar panels. I like the flexible due to no roof penetrations but my mind is open to either. I need to get on the roof and measure the area I have to work with. Brand and amp ratings of charge controllers. I like the idea of having Bluetooth. As far as amp rating I'm clueless.

I considered flexible panels, but if they are mounted directly to the roof there is no air gap for heat dissipation. Mounting rigid panels without roof penetration is quite doable. I made mounts similar to those sold by AM Solar and attached them with VHB tape. So far so good, and AM Solar claims they have never lost a panel they installed with tape. I have read some recommendations that you can use a controller rated quite a bit lower than the rated output of your panels. For example, I have 1600 watts of solar, and I have seen recommendations of 80 to 100 A controllers for that wattage. However, that would mean that if you ever get close to the rated panel output you would not be able to use the full power generated. I have not used mine in optimal summer conditions yet and have already seen 1200 watts, so I wanted to be prepared. I went with two Victron 60A controllers.

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