DIY solar installation

[Jim McGarvie]

Can anyone point me to a good website to learn the basics? I have been through most of the AM Solar site (https://amsolar.com/diy-rv-solar-instructions/) and it is very helpful, but I still have questions.

Some of you may be able to answer one vehicle-specific question I have about routing the cables from the panels to the controller. I plan to install the controller in the rearmost curbside compartment where the inverter is, and immediately behind the battery compartment. The refrigerator is in a slide so using that vent is not an option. I seem to remember reading accounts of running cables (both solar and rear view camera) down through the rear cap, and that sounds appealing to me, but now I can't find those articles.

I have looked up from the engine compartment and from below the chassis, and it appears there is a bulkhead the entire width of the rear cap. It isn't clear to me where would be a good place to go through that bulkhead.

Thanks for any help and advice.

Jim

[Guest Cruzbill]

I don't know how to run the cables on your coach, but I would suggest using big cable from your roof mounted junction box to the solar controller, like #4, to limit voltage drop. You can check for voltage drop for your un by using an on-line calculator:

 

https://rimstar.org/renewnrg/solar_voltage_drop_table_calculator_wire_sizing_for_dc.htm

[Jim McGarvie]

1 hour ago, Cruzbill said:

I don't know how to run the cables on your coach, but I would suggest using big cable from your roof mounted junction box to the solar controller, like #4, to limit voltage drop. You can check for voltage drop for your un by using an on-line calculator:

 

https://rimstar.org/renewnrg/solar_voltage_drop_table_calculator_wire_sizing_for_dc.htm

Thanks, Bill, I think that's good advice. I think #4 is about what I'll want. And thanks for the link, that's a good resource.

[TomV48]

I helped on one install, Thor gasser, that went down through the top of the right rear cap and down to a low point of the rear bay, which in his case is an outdoor kitchen,  forward to the next bay where batteries are and bolted the 60 amp charge controller to upper part of the bay. Then short run to batteries below it.  So far, so good and his went on six or so months age with no problem yet.  He's camped next to me at the beach this week and his 8 100 watt panels and six GC2 batteries seem to be supporting his coach and Whirlpool res frig pretty well; overcast mornings and all.

BTW, 4 ga seems a bit hefty.  Run your panels at least pairs in series to a junction and it would take a big bunch of solar to need 4 ga down from the junction box. I have three pairs of 100 watt panels, to a 6 ga welding wire ( Windy Nation through Amazon  ) and only justify that big wire "in case" I decide to add 2 or 4 more panels later.

 

[hitechpete]

9 hours ago, Jim McGarvie said:

Can anyone point me to a good website to learn the basics? I have been through most of the AM Solar site (https://amsolar.com/diy-rv-solar-instructions/) and it is very helpful, but I still have questions.

Some of you may be able to answer one vehicle-specific question I have about routing the cables from the panels to the controller. I plan to install the controller in the rearmost curbside compartment where the inverter is, and immediately behind the battery compartment. The refrigerator is in a slide so using that vent is not an option. I seem to remember reading accounts of running cables (both solar and rear view camera) down through the rear cap, and that sounds appealing to me, but now I can't find those articles.

I have looked up from the engine compartment and from below the chassis, and it appears there is a bulkhead the entire width of the rear cap. It isn't clear to me where would be a good place to go through that bulkhead.

Thanks for any help and advice.

Jim

I would take a look at Will Prowse on YouTube, he does a several videos on solar power for beginners upwards.

[Jim McGarvie]

4 hours ago, TomV48 said:

BTW, 4 ga seems a bit hefty.  Run your panels at least pairs in series to a junction and it would take a big bunch of solar to need 4 ga down from the junction box. I have three pairs of 100 watt panels, to a 6 ga welding wire ( Windy Nation through Amazon  ) and only justify that big wire "in case" I decide to add 2 or 4 more panels later.

 

Thanks, Tom. I haven't yet figured out the series/parallel thing, so haven't figured how many amps I'll be dealing with. At first blush I assumed series would be better, to minimize wire size, but then learned that apparently panels in series are more impacted by shadows.

And thanks too for the tip on the welding wire.

Jim

3 hours ago, hitechpete said:

I would take a look at Will Prowse on YouTube, he does a several videos on solar power for beginners upwards.

Thanks, Peter, I will check it out.

Jim

[wamcneil]

13 hours ago, Jim McGarvie said:

Can anyone point me to a good website to learn the basics? I have been through most of the AM Solar site (https://amsolar.com/diy-rv-solar-instructions/) and it is very helpful, but I still have questions.

Thanks for any help and advice.

Jim

Sounds like you already have a good handle on the basics, but rvwithtito.com has a good beginner guide and some videos walking through his setup and explaining the decisions that drove each part of his system. 
He gets really detailed; shows his rooftop junction box and talks about roof penetration. I copied his junction box and DIN rail terminal block. And I’m jealous of his symarine battery monitor...

Personally, I ran big wires down from the junction box to the controller and then combined the panels in series (2 strings of 3 panels each). That way if I later decide that shading is a problem, I can rewire the junction box and run the panels in parallel without  causing much hardship.

Cheers

Walter

[Jim McGarvie]

31 minutes ago, wamcneil said:

Sounds like you already have a good handle on the basics, but rvwithtito.com has a good beginner guide and some videos walking through his setup and explaining the decisions that drove each part of his system.

Looks like a good resource, Walter. Thanks.

 

[Guest Tim503]

The space around the vent pipe has some room. You could unscrew it and see if it is viable but most likely would need to remove a closet inside panel which is not hard or use fish wire down to the black gray tanks. I would not worry about changing from the #10 if that is what comes off the panels. You're only talking about 12' if the wire gets warm you can upgrade it later. I run 3 60 cell panels which are 3.5' x 5.5' in a series. Together they are 10' by 5.5' and puts out 90 volts but 8 amps. I run them 20' on the #10 wire and just put them in at the solar controller. It puts out 500 watts on a sunny afternoon and cost $100 used $300 total. I would keep the controller in the house so you can monitor it unless it has a way to take the panel off. Of course from the panel to the batteries you would want #6 or #4 for a 12 volt output. Basically use the largest size the controller accepts. I use the Midnight Solar and very happy with it. You're most likely trying to fit panels around all the stuff on the roof so it will be a whole different process. Good luck. I also changed over to a 24volt system and power the house 12 volt on a IOTA 30 amp converter. I thought I would need a separate 12 volt battery for that but this is working good. My water pump would get a low voltage and would not turn off. So far I'm very happy with the constant 12 volt power not being affected by battery up and down voltage. Anyone using a residential fridge should consider that with all the other 120 volt systems, putting house lights on it is just like any appliance.

Edited August 8, 2020 by Tim503

[W7BE_Bob]

I've run wires from the roof in 3 places.  1. Cell antenna in PS back corner down through a cabinet to amp under the bed and forward - see below. 2. Sat dish midships down into a cabinet above the TV.  3. Solar panel 10 ga near #2 all the way down to the solar controller in  the basement.

I setup #1 to run the coax through the A/C ducting to mid ships ie I had a string routed to pull the coax. But needed slightly longer coax. So instead the cell antenna coax reaches the amp under the bed and coax runs forward DS in the plumbing and  wiring channel midships  to the internal antenna. I've also run AC wiring in that channel back to midships. 

Do more research, stop thinking AM solar (mostly small parallel panels rightf) and understand series series/parallel. Tim503 gave good information except for changing warm wires - absolutely not - use a wiring calculator and get it right the first time. 

Do you have closets/cabinets to run  the wiress vertically? Do you have a rear camera  that you can remove and see in the cap? I'd drill up into the cap from the engine room and run the wires down from the roof. You should be able to get a 1/8" fiberglas wire puller top to bottom and pull the wires.

Panel prices are low. This month there was a add for 300W panels for $100. MPPT controllers are expensive. I made a scaled diagram of my roof and paper rectangles for various sized panels to determine how to go. Also looked at $/W and W/sq ft. 12V parallel panels were loosers. A 12V panel system with PWM was the same cost as serial with MPPT.

 

[W7BE_Bob]

My solar somewhat like Tim503. 3x250W serial panels. 62' total UV wire which includes the panel pigtails. The wires run straight  down midships behind pulled cabinet interior sides to the basement. No visible wiring. The controller MS MPPT 60 is in the basement next to the inverter. Small cable back up to the remote. 2 small sets of wires to the DS rear batteries for battery tempeature and remote voltage sense. Controller DC 4 ga wires to the inverter 4/O wires to the batteries 21' away (42' of 4/O). Wiring loss panels to battery is 1.5% - very low.

Serial is more shade tolerant than parallel due to the bypass diodes. Most posters don't understand this and there is lot of misinformation on this and other aspects of solar. I have a lot of solar information posted on RV net including graphs form the controller showing how bypass diodes work. Go to rv.net, click advanced search and in Message Author enter CA Traveler with caps and blank. Maybe enter solar for keyword. There are some recent posts. Then repeat this but change Date Posted to Archive. You should find a lot of information. If you decide on parallel or serial/parallel there are lots of posts on this and equipment. Be cautious  as posts reflect what we know or read  and are not always correct. 

To jump start - my solar install: https://www.rv.net/forum/index.cfm/fuseaction/thread/tid/28119528.cfm 

 

BTW If you plow through the above solar  install you'll find that my roof is basically not attached to  to the ceiling cross frames. I had no problems with the initial install and drove some distance. Later I added some additonal 4'+ aluminum bracing in case I ever got into very high winds. And like a lot of things you'll discover misinformation on wind and raised panels. Never mind that while not the norm various rigs have raised panels.

The extra bracing due to the marginal roof design may have saved the day last summer. On  I8 we heard a LOUD bank. DW yellled your solar panels blew off! I looked in the rear mirror and saw the 20' awing with roller sailing across I8. DW saw one arm extending out 10' and yelled It's the awning. There was some history with my CareLess awning and it hasn't been  replaced. 

[Jim McGarvie]

Wow, Bob, thanks for taking the time to write such detailed, informative replies! I've had to read each of your two messages two or three times to try to absorb most of it. I'll try to organize my responses below:

Regarding routing of the wires from the panels to the controller, I'm pretty sure the rear cap is my best bet. It leads almost directly to the rear curbside basement compartment where the controller will be located. And as a side benefit, if the connection on the roof leaks it won't hurt anything.

And yes, I will use an ampacity chart to determine the proper wire gauge.

Thank you for the information regarding serial versus parallel. I was concerned about the shading issue, but unaware of the diodes. I certainly see the advantage of serial wiring with regard to wire size. Now all I need to do is find panels with the diodes.

Speaking of choosing panels, I am still torn between traditional glass panels and the new flexible panels. My son has installed Renogy flexible panels on three RVs, and is quite happy with them so far. Granted, they have not been in service very long. I'm aware of the bad reputation flexible panels have had, but maybe the newer ones are OK? Renogy has a 25-year performance warranty on theirs, which I think is comparable to traditional, rigid panels.

Sorry to hear about your awning; hope that works out.

Jim

 

[Jim McGarvie]

Thanks largely to what I have learned on this forum, I am getting better educated on the subject of DIY solar installation. I have planned my installation for the most part, but am still undecided on a provider/source. I was originally leaning toward Renogy flexible panels but have pretty much decided against flexible panels, and now having second thoughts about Renogy as a company.

Any suggestions?

Thanks.

Jim

[Ivan K]

I am using 200+ watt panels from a company selling on eBay. This was my 4th panel. They come with warranty and a test chart. Once a while he sells some that tested well over 200w and that's what I get. They are 12v, perfect for my serial setup. The company is High-tech Solar, I think in Michigan, no complaints.

[Jim McGarvie]

3 minutes ago, Ivan K said:

I am using 200+ watt panels from a company selling on eBay. This was my 4th panel. They come with warranty and a test chart. Once a while he sells some that tested well over 200w and that's what I get. They are 12v, perfect for my serial setup. The company is High-tech Solar, I think in Michigan, no complaints.

 

Thanks Ivan.

[wamcneil]

3 hours ago, Ivan K said:

I am using 200+ watt panels from a company selling on eBay. This was my 4th panel. They come with warranty and a test chart. Once a while he sells some that tested well over 200w and that's what I get. They are 12v, perfect for my serial setup. The company is High-tech Solar, I think in Michigan, no complaints.

I've got a couple of those also, and some 180w Grape Solar from Home Depot. 

I like the shape and size of the 180-200 panels. They fit nicely between the ACs and the edge of the roof.

Cheers

Walter

Edited August 11, 2020 by wamcneil

[amphi_sc]

On 8/11/2020 at 8:49 AM, Ivan K said:

I am using 200+ watt panels from a company selling on eBay. This was my 4th panel. They come with warranty and a test chart. Once a while he sells some that tested well over 200w and that's what I get. They are 12v, perfect for my serial setup. The company is High-tech Solar, I think in Michigan, no complaints.

I also have used these panels from this particular eBay seller and have been a very satisfied customer.  I have both the 4x9 and 6x6 cell arrangements to fit on my roof the way I wanted. I would buy his panels again if I had capacity and real estate.

[Jim McGarvie]

Can either of you send the link to this seller's eBay site? I have searched for high-tech solar and for 200+25% watt and nothing comes up.

Thanks.

 

[Ivan K]

Try this, I have contacted him through eBay when I wanted one of the better ones and he let me know when it was posted  if there wasn't one listed already..

https://www.ebay.com/str/Hightec-Solar-Inc?_trksid=p2047675.l2563

[Jim McGarvie]

3 minutes ago, Ivan K said:

Try this, I have contacted him through eBay when I wanted one of the better ones and he let me know when it was posted  if there wasn't one listed already..

https://www.ebay.com/str/Hightec-Solar-Inc?_trksid=p2047675.l2563

That worked. Thanks.

[Guest Tim503]

Let me put this here one more time. Your best deal is to buy used panels on craigslist or where ever. Get the 30 volt panels. They are made for 24 volt systems but with a MPPT controller it doesn't matter anymore. If you can fit a 3.5 x 5.5' or 6.5' panels on the roof (that is a 60 cell or 72 cell) it is the best value at $100 each. Even if they are 5 years old but work I would buy them. Put them in a series of 3 which is about 90 volts at 8-9 amps which is a good conversion into a 12 volt battery or better go to 24 volt battery to run you inverter. Use an IOTA 120 volt to 12 volt converter 30 amp to run your house lights and fan, water pump motors they also have a 55 amp converter puts out 13.5 volts and they work good and are cheap. Check Don Rowe.

[Guest Tim503]

Let me put this here one more time. Your best deal is to buy used panels on craigslist or where ever. Get the 30 volt panels. They are made for 24 volt systems but with a MPPT controller it doesn't matter anymore. If you can fit a 3.5 x 5.5' or 6.5' panels on the roof (that is a 60 cell or 72 cell) it is the best value at $100 each. Even if they are 5 years old but work I would buy them. Put them in a series of 3 which is about 90 volts at 8-9 amps which is a good conversion into a 12 volt battery or better go to 24 volt battery to run you inverter. Use an IOTA 120 volt to 12 volt converter 30 amp to run your house lights and fan, water pump motors they also have a 55 amp converter puts out 13.5 volts and they work good and are cheap. Check Don Rowe.

One thing I haven't heard mention and that is the panels should not be sealed to the roof. They need air around them and operate better if not to hot. You best scenario is a cold clear bright day for maximum electricity conversion. The other benefit of keeping them spaced above your roof is the motorhome stays cooler. You might want to think about installing them over each AC unit, that way the AC will stay cooler and operate more efficiently but it would look weird and be an engineering chore. What ever you do, keep them an inch or two above the roof. I installed mine on 2x4s.Douglas Fir.  Three units are 10' which is two boards or two 10' angle irons. There is a heavy duty angle iron for shelving units you could look into. I believe it is 1.5 x 3" slotted. Then you have a 3 panel unit. You can add more units and securing this unit is easier than securing each panel and each hole into the roof. Secure the unit with 4 tie downs or secure each panel with 4 tie downs per panel.

[jreich888]

On 8/12/2020 at 1:16 PM, Ivan K said:

Try this, I have contacted him through eBay when I wanted one of the better ones and he let me know when it was posted  if there wasn't one listed already..

https://www.ebay.com/str/Hightec-Solar-Inc?_trksid=p2047675.l2563

I've bought Hightech panels from Continuous Resources in Utah, and they are cheaper than this ebay "direct" ($185 for a 200W panel).  And CR had good support; one of the pieces I bought (a controller display) from them was broken, they got a replacement to me very quickly.

https://www.continuousresources.com/collections/solar-panels-and-hardware/products/200w-36-cell-12v-nominal-solar-panel-5-busbar

[Ivan K]

30 minutes ago, jreich888 said:

I've bought Hightech panels from Continuous Resources in Utah, and they are cheaper than this ebay "direct" ($185 for a 200W panel).  And CR had good support; one of the pieces I bought (a controller display) from them was broken, they got a replacement to me very quickly.

https://www.continuousresources.com/collections/solar-panels-and-hardware/products/200w-36-cell-12v-nominal-solar-panel-5-busbar

Notice that the ones I bought tested a little higher than 200W, this is why I got them for few extra $ to hopefully get the most from our limited space. Otherwise the price is the same as your source for regular 200W panels, same thing. 

[Jim McGarvie]

15 hours ago, Tim503 said:

Let me put this here one more time. Your best deal is to buy used panels on craigslist or where ever. Get the 30 volt panels. They are made for 24 volt systems but with a MPPT controller it doesn't matter anymore. If you can fit a 3.5 x 5.5' or 6.5' panels on the roof (that is a 60 cell or 72 cell) it is the best value at $100 each. Even if they are 5 years old but work I would buy them. Put them in a series of 3 which is about 90 volts at 8-9 amps which is a good conversion into a 12 volt battery or better go to 24 volt battery to run you inverter. Use an IOTA 120 volt to 12 volt converter 30 amp to run your house lights and fan, water pump motors they also have a 55 amp converter puts out 13.5 volts and they work good and are cheap. Check Don Rowe.

One thing I haven't heard mention and that is the panels should not be sealed to the roof. They need air around them and operate better if not to hot. You best scenario is a cold clear bright day for maximum electricity conversion. The other benefit of keeping them spaced above your roof is the motorhome stays cooler. You might want to think about installing them over each AC unit, that way the AC will stay cooler and operate more efficiently but it would look weird and be an engineering chore. What ever you do, keep them an inch or two above the roof. I installed mine on 2x4s.Douglas Fir.  Three units are 10' which is two boards or two 10' angle irons. There is a heavy duty angle iron for shelving units you could look into. I believe it is 1.5 x 3" slotted. Then you have a 3 panel unit. You can add more units and securing this unit is easier than securing each panel and each hole into the roof. Secure the unit with 4 tie downs or secure each panel with 4 tie downs per panel.

Thanks for the input, Tim. Unfortunately I don't have the acreage on our motorhome roof for panels that wide. And I definitely will elevate the panels above the roof.

Jim

1 hour ago, jreich888 said:

I've bought Hightech panels from Continuous Resources in Utah, and they are cheaper than this ebay "direct" ($185 for a 200W panel).  And CR had good support; one of the pieces I bought (a controller display) from them was broken, they got a replacement to me very quickly.

https://www.continuousresources.com/collections/solar-panels-and-hardware/products/200w-36-cell-12v-nominal-solar-panel-5-busbar

Thanks for that link, Jason. That is the best deal I have seen so far for U.S.-made panels.

Jim