Project complete: 500w solar install, plus 2000w inverter
(This is on one of my 2015 Thor Majestic 28a RVs)
I wanted to put this together in the hopes that some would find it helpful (...I know I've learned so much from these forums!).
Total cost:
- For the 500w solar:
$225 for the system, and another ~$150 in additional items
~$375 total
- For the 2000w inverter:
$240 for the inverter, and another $100 for cables, outlets, etc
~$340
Total time: ~20 hours
I finally had some free time to tackle this project...adding 500w of solar and a 2000w inverter. Happy to report that things seem to be working well. Here's what I did...
First, I wanted to start with a "clean canvas" (aka: roof). I had notice my Dicor caulking around my front/rear and also around the vents looked like it was starting to crack. I happened to have several gallons of Dicor roof sealant (step 1 and 2) from a previous RV I never got around to sealing, so I thought I'd start by resealing the roof. Here is a link to that project:
https://www.rv.net/forum/index.cfm/fuseaction/thread/tid/30201452.cfm
With a clean canvas, it was time to start...
Background: My initial plan was to add 200-250w of solar on the roof, just to provide some modest boondocking capability. My RV has two 100AH Lead Acid (deep cycle) batteries (will be adding a 3rd battery soon). I also have a 4000w generator, but I hate running it while camping (โฆkills the peacefulness of the great outdoors). It is never my intention though to have a serious (large) battery bank and "live off the grid" for extended periods of time. I happened to be visiting Phoenix Arizona late last year and I had stumbled across SanTan Solar (www.SanTanSolar.com) (located in Gilbert, Az 10 minutes away) who sells used residential solar panels and all the components to make an RV solar setup. I had planned on buying a 250w system from them which included one 250w panel, an MPPT charge controller, fuse and a breaker, mounting hardware, and all the wiring (for $165). Seemed like a great price. Well, when I arrived I was surprised to see they were having a sale on their 250w panels and they were just $35 each(!). These are only 10 year old panels and I tested each of them. Soooo, I decided to bump my solar system up to 500w "just because". I was out the door with a complete 500w system with all the components for just $225 (two 250w panels required a bigger MPPT controller and one extra inline 15a fuse).
Here is a before picture of my roof:
On top of the AC is a disabled solar trickle charger that I will remove.
Advanced tip: Before I got started, I tested the entire system on the ground. Layed the two panels on the ground, connected the charge controller to the batteries, then connected the panels to the charge controller. Yepโฆeverything seemed to work. I even did a test where I drained my batteries by ~80AH over night to see if the solar setup would properly do its thing. The test showed me that everything worked as planned. (I certainly didnโt want to attach some panels to the roof with tape and holes/screws, etc only to find out that the system wasnโt working). If you are doing a solar install, I would suggest you do the same.
I then started by mounting the two panels near the front of the RV. I wanted to make sure I had a pathway to walk between them. I also wanted them to be as far as reasonable from the AC to reduce any possible shading impact. My plan was to use five Z-bracketsโฆ.Two on each side and one on the lead edge (front). I wanted to do everything possible to avoid these tearing off the roof while driving down the freeway at 65mph into a strong headwind. I used 3M VHB Tape between the bracket and the panel and between the bracket and the roof surface. For those who havenโt used 3M VHB tape beforeโฆ.it is STRONG. Since my roof is EPDM, I also bolted the brackets to the panel frame and bolted the brackets to the roof surface. Even though the VHB tape is strong, I would never trust it completely on its own (especially on an EPDM roof).
When I drilled the pilot holes for the brackets into the roof, I was a little surprised by how thin the plywood is. I can easily walk on my roof and it feels quite solid, so I thought it would be at least ยผโ plywood, but honestly I think it is less. When I screwed the panels to the roof itself, I felt โokayโ about the strength, but not great. I always try to think safety first, and I usually decide to overkill it rather than risk it. So, now the panels were VHB taped and screwed to the roof and I didnโt want to even attempt to take them off (โฆwhich I guess is a good sign that they were actually on there pretty good in the first place). So I bought some simple โLโ brackets from Home Depot and I added 2 more brackets on the front leading edge and one on the rear edge. So in total, each panel has 8 brackets (16 screws total holding them down). Those panels seem like they are not going anywhere now!
I will probably hit them with another layer of Dicor and trim off those lengthy bolts.
Advanced tip for applying Dicor: After the panels were securely fastened to the roof (and once I retested the system to make sure it was properly working) it was time to use Dicor self leveling sealer/caulking. For a moment I wondered, โHow am I going to apply this Dicor BEHIND the Z-brackets (underneath the panel). There is only about 1 inch of clearance between the roof and the panel framing. Then I came up with an ideaโฆ I bought a couple feet of plastic tubing (Like this: https://tinyurl.com/tubing4dicor) and a small hose clamp. Then I cut off a ~1 foot piece and fastened it to the end of the Dicor tube. Because this tubing comes wound up, it naturally has a curved bend to it. A one foot piece gave approximately a 180 degree bend. This made it simple for me to apply a healthy amount of Dicor BEHIND the bracket exactly where I wanted/needed to. ๐
I wanted to keep all the wires very neat and tidy. So I used zip tie mounts in several places and zip ties. To keep the wires tidy underneath the panel itself (and not flapping around), hereโs what I did:
I made sure I left a little bit of wire โslackโ where the connections were made joining the two panels just in case I need to replace a fuse or possibly add another panel in the future (unlikely). Here is what the panels look like installed:
(I later Dicorโed over the wire on the right coming from the panels down the right side of that picture).
When I put solar onto my other RV I plan on hitting this wire with another round of Dicor.
Because I am fairly certain I will never add more solar panels to this roof, I went with 10AWG wire. It is large enough to handle the ~16 max amps these panels could generate. Iโve got a ~40โ run to my solar charge controller, but 10AWG wire can do that with about a 3.5% drop in voltage. RememberโฆI only really needed 200-250w, so I didnโt need to worry about this relatively minor drop. I ran the wires down my refrigerator vent which was pretty convenient. During the stretch where the wire is running behind the refrigerator, I put it in electrical conduit and fixed it in place away from any hot components of the refrigerator cooling unit. From there, the wires went through the floor and popped out underneath the RV where I could route the wires (in flex conduit, wrapped in electrical tape) forward and to the driverโs side of the RV underneath the dinette seat. Zip-tied the wiring securely along the way. Under the driver side dinetteโฆthatโs where I put the solar charge controller and my 2000w inverter.
Side note: If you havenโt done this before, I highly recommend you grab 10-20 strong zip ties and you crawl all around underneath your RV. You will likely find PLENTY of wires you can secure better running all over underneath your RV.
From my 2000w inverter, I ran a parallel set (two positive/two negative) of 2/0 cables (~8โ long) to my battery connections (Iโll be adding a 3rd coach battery in the next couple of weeks). This should handle the large potential current draw from my batteries under the possible heavy load of the inverter. My inverter is mounted right next to my solar charge controller. From my solar charge controller, I have a ~2โ 6AWG wire (thickest that will fit in the solar charge controller) going to my inverter Pos/Neg posts (hence my batteries) with a resettable fuse in between (in case I want to disable the solar at any point while doing other work on the RV, etc). This makes my voltage drop between my solar controller and batteries pretty much negligible.
From my inverter, I created three 120v outlets (two near the dinette, and one all the way back in the bedroom). For the rear bedroom outlet, I used 14/2 outdoor Romex and put it in flexible conduit and routed it mostly underneath the RV fastening it with plenty of other wires running under there. Here is a picture of the outlet added at the dinette.
Here is my Aili battery monitor I installed previously. It now shows me that my 500w of solar constantly keeps my batteries at 100% :C If you donโt have a battery monitor, you should get one. It is the easiest way to know at all times what is happening with your batteries/solar/charging/etc. Very handy, and this one only costs ~$45.
For the places where I was going to be routing several wires (primarily under/through my dinetteโฆSolar wires from the panels, 2 sets of thick cables from my inverter to the batteries, one wire in conduit to the rear bedroom outlet from inverter) I had to drill a sizable hole through the floor and out the bottom of the RV. I found that if I use a 1 5/8โ drill bit it makes a nice size hole and then I use one of these 1-1/2 in. x 6 in. White Plastic Flanged Strainer Sink Drain Tailpiece Extension Tubes (https://www.homedepot.com/p/Everbilt-1-1-2-in-x-6-in-White-Plastic-Flanged-Strainer-Sink-Drain-Tailpiece-Extension-Tube-C9800/205154040) cut so that it sticks out about an inch out the bottom of the RV. I could glue this in place and it provides for a smooth exit out of the bottom of the RV (instead of rubbing on the metal undercoating that was drilled through. Once all the wires were done and the system was complete, I stuffed some steel wool inside this tubing so that it was about halfway between the floor and the bottom of the RV, and then I filled the rest (top and bottom) with some sealant foam (like this: https://www.homedepot.com/p/Loctite-TITE-FOAM-Window-and-Door-12-Fl-oz-Insulating-Spray-Foam-Sealant-2260115/302135916?ITC=AUC-62427-23-12140). This sealing (and steel wool) should make it rodent proof and air-tight.
Here is a fairly complete list of components:
- Two 250w residential panels (https://store.santansolar.com/product/santan-solar-t-series-250w/)
- Two 15amp inline MC4 fuses (Amazon.com: Renogy 15A Male and Female Connector Waterproof in-Line Fuse Holder w/Fuse, Black: Garden & Outdoor)
- One Y-branch MC4 parallel wire connector
- 40โ of 10AWG wire with MC4 connector ends
- Two 6โx16โ screens from Home Depot to re-cover the refrigerator screen that I cut to gain access to drop the wires without having to pull the refrigerator (Gibraltar Building Products 14 in. x 6 in. Galvanized Steel 2-Way Reversible Vent-TW146-1/8 - The Home Depot)
- 5โ of electrical conduit to run behind the refrigerator to keep the wires away from the hot components of the cooling unit of the refrigerator
- Zip tie mounts and zip ties to keep the wires tidy along the way (https://www.amazon.com/gp/product/B07M69LTLJ/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1)
- 20โ of 2/0 cables to cut and double up and run two pairs from inverter to batteries (https://www.amazon.com/gp/product/B07FZWBKNZ/ref=ppx_yo_dt_b_asin_title_o07_s00?ie=UTF8&psc=1)
- Bag of copper lug connectors for making custom length cables (https://www.amazon.com/gp/product/B08R6TX3XM/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1)
- Crimper tool for making custom length cables (https://www.amazon.com/gp/product/B07V6V7XZC/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1)
- 5 tubes of Dicor self-leveling sealer
- 1โ plastic tubing and a small hose clamp (to apply Dicor BEHIND the Z-brackets)
- Two 1-1/2 in. x 6 in. White Plastic Flanged Strainer Sink Drain Tailpiece Extension Tubes
- Steel wool and foam sealant (to seal up any openings made in the bottom of the RV)
- Romex, 3 junction boxes and outlet receptacles and cover plates.
- Plenty of electrical tape
- 30 amp MPPT solar controller (https://store.santansolar.com/product/epever-3210-30a-mppt-solar-charge-controller/)
- 2000w Pure Sine Wave Inverter
- Two 40amp resettable fusesโฆone between solar panels and the controller, and one between the solar controller and the batteries. These are located right next to the solar controller so I can effectively enable/disable the solar anytime I need (https://www.amazon.com/gp/product/B07KF2PV6V/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1 )
- Misc: Screws, washers, nuts, bolts
I didnโt really keep track of how many hours this project took me. Probably ~20 hours, which included lots of trips back and forth to Home Depot for misc items. I had fun (mostly) doing it, and learned a lot. The good news is that Iโm putting another 400w solar system on my nearly identical Majestic 28a. While I was performing this current 500w install, I bought double the supplies/parts knowing that I have another one to do. I suspect Iโll be able to install the next solar system on my other RV in probably half the time now that I know all the tricks (and have all the components on hand). This was my first solar project and Iโm very happy with the results. Canโt wait to head off-grid somewhere soon!
Happy Camping all!
Chris
(This is on one of my 2015 Thor Majestic 28a RVs)
I wanted to put this together in the hopes that some would find it helpful (...I know I've learned so much from these forums!).
Total cost:
- For the 500w solar:
$225 for the system, and another ~$150 in additional items
~$375 total
- For the 2000w inverter:
$240 for the inverter, and another $100 for cables, outlets, etc
~$340
Total time: ~20 hours
I finally had some free time to tackle this project...adding 500w of solar and a 2000w inverter. Happy to report that things seem to be working well. Here's what I did...
First, I wanted to start with a "clean canvas" (aka: roof). I had notice my Dicor caulking around my front/rear and also around the vents looked like it was starting to crack. I happened to have several gallons of Dicor roof sealant (step 1 and 2) from a previous RV I never got around to sealing, so I thought I'd start by resealing the roof. Here is a link to that project:
https://www.rv.net/forum/index.cfm/fuseaction/thread/tid/30201452.cfm
With a clean canvas, it was time to start...
Background: My initial plan was to add 200-250w of solar on the roof, just to provide some modest boondocking capability. My RV has two 100AH Lead Acid (deep cycle) batteries (will be adding a 3rd battery soon). I also have a 4000w generator, but I hate running it while camping (โฆkills the peacefulness of the great outdoors). It is never my intention though to have a serious (large) battery bank and "live off the grid" for extended periods of time. I happened to be visiting Phoenix Arizona late last year and I had stumbled across SanTan Solar (www.SanTanSolar.com) (located in Gilbert, Az 10 minutes away) who sells used residential solar panels and all the components to make an RV solar setup. I had planned on buying a 250w system from them which included one 250w panel, an MPPT charge controller, fuse and a breaker, mounting hardware, and all the wiring (for $165). Seemed like a great price. Well, when I arrived I was surprised to see they were having a sale on their 250w panels and they were just $35 each(!). These are only 10 year old panels and I tested each of them. Soooo, I decided to bump my solar system up to 500w "just because". I was out the door with a complete 500w system with all the components for just $225 (two 250w panels required a bigger MPPT controller and one extra inline 15a fuse).
Here is a before picture of my roof:
On top of the AC is a disabled solar trickle charger that I will remove.
Advanced tip: Before I got started, I tested the entire system on the ground. Layed the two panels on the ground, connected the charge controller to the batteries, then connected the panels to the charge controller. Yepโฆeverything seemed to work. I even did a test where I drained my batteries by ~80AH over night to see if the solar setup would properly do its thing. The test showed me that everything worked as planned. (I certainly didnโt want to attach some panels to the roof with tape and holes/screws, etc only to find out that the system wasnโt working). If you are doing a solar install, I would suggest you do the same.
I then started by mounting the two panels near the front of the RV. I wanted to make sure I had a pathway to walk between them. I also wanted them to be as far as reasonable from the AC to reduce any possible shading impact. My plan was to use five Z-bracketsโฆ.Two on each side and one on the lead edge (front). I wanted to do everything possible to avoid these tearing off the roof while driving down the freeway at 65mph into a strong headwind. I used 3M VHB Tape between the bracket and the panel and between the bracket and the roof surface. For those who havenโt used 3M VHB tape beforeโฆ.it is STRONG. Since my roof is EPDM, I also bolted the brackets to the panel frame and bolted the brackets to the roof surface. Even though the VHB tape is strong, I would never trust it completely on its own (especially on an EPDM roof).
When I drilled the pilot holes for the brackets into the roof, I was a little surprised by how thin the plywood is. I can easily walk on my roof and it feels quite solid, so I thought it would be at least ยผโ plywood, but honestly I think it is less. When I screwed the panels to the roof itself, I felt โokayโ about the strength, but not great. I always try to think safety first, and I usually decide to overkill it rather than risk it. So, now the panels were VHB taped and screwed to the roof and I didnโt want to even attempt to take them off (โฆwhich I guess is a good sign that they were actually on there pretty good in the first place). So I bought some simple โLโ brackets from Home Depot and I added 2 more brackets on the front leading edge and one on the rear edge. So in total, each panel has 8 brackets (16 screws total holding them down). Those panels seem like they are not going anywhere now!
I will probably hit them with another layer of Dicor and trim off those lengthy bolts.
Advanced tip for applying Dicor: After the panels were securely fastened to the roof (and once I retested the system to make sure it was properly working) it was time to use Dicor self leveling sealer/caulking. For a moment I wondered, โHow am I going to apply this Dicor BEHIND the Z-brackets (underneath the panel). There is only about 1 inch of clearance between the roof and the panel framing. Then I came up with an ideaโฆ I bought a couple feet of plastic tubing (Like this: https://tinyurl.com/tubing4dicor) and a small hose clamp. Then I cut off a ~1 foot piece and fastened it to the end of the Dicor tube. Because this tubing comes wound up, it naturally has a curved bend to it. A one foot piece gave approximately a 180 degree bend. This made it simple for me to apply a healthy amount of Dicor BEHIND the bracket exactly where I wanted/needed to. ๐
I wanted to keep all the wires very neat and tidy. So I used zip tie mounts in several places and zip ties. To keep the wires tidy underneath the panel itself (and not flapping around), hereโs what I did:
I made sure I left a little bit of wire โslackโ where the connections were made joining the two panels just in case I need to replace a fuse or possibly add another panel in the future (unlikely). Here is what the panels look like installed:
(I later Dicorโed over the wire on the right coming from the panels down the right side of that picture).
When I put solar onto my other RV I plan on hitting this wire with another round of Dicor.
Because I am fairly certain I will never add more solar panels to this roof, I went with 10AWG wire. It is large enough to handle the ~16 max amps these panels could generate. Iโve got a ~40โ run to my solar charge controller, but 10AWG wire can do that with about a 3.5% drop in voltage. RememberโฆI only really needed 200-250w, so I didnโt need to worry about this relatively minor drop. I ran the wires down my refrigerator vent which was pretty convenient. During the stretch where the wire is running behind the refrigerator, I put it in electrical conduit and fixed it in place away from any hot components of the refrigerator cooling unit. From there, the wires went through the floor and popped out underneath the RV where I could route the wires (in flex conduit, wrapped in electrical tape) forward and to the driverโs side of the RV underneath the dinette seat. Zip-tied the wiring securely along the way. Under the driver side dinetteโฆthatโs where I put the solar charge controller and my 2000w inverter.
Side note: If you havenโt done this before, I highly recommend you grab 10-20 strong zip ties and you crawl all around underneath your RV. You will likely find PLENTY of wires you can secure better running all over underneath your RV.
From my 2000w inverter, I ran a parallel set (two positive/two negative) of 2/0 cables (~8โ long) to my battery connections (Iโll be adding a 3rd coach battery in the next couple of weeks). This should handle the large potential current draw from my batteries under the possible heavy load of the inverter. My inverter is mounted right next to my solar charge controller. From my solar charge controller, I have a ~2โ 6AWG wire (thickest that will fit in the solar charge controller) going to my inverter Pos/Neg posts (hence my batteries) with a resettable fuse in between (in case I want to disable the solar at any point while doing other work on the RV, etc). This makes my voltage drop between my solar controller and batteries pretty much negligible.
From my inverter, I created three 120v outlets (two near the dinette, and one all the way back in the bedroom). For the rear bedroom outlet, I used 14/2 outdoor Romex and put it in flexible conduit and routed it mostly underneath the RV fastening it with plenty of other wires running under there. Here is a picture of the outlet added at the dinette.
Here is my Aili battery monitor I installed previously. It now shows me that my 500w of solar constantly keeps my batteries at 100% :C If you donโt have a battery monitor, you should get one. It is the easiest way to know at all times what is happening with your batteries/solar/charging/etc. Very handy, and this one only costs ~$45.
For the places where I was going to be routing several wires (primarily under/through my dinetteโฆSolar wires from the panels, 2 sets of thick cables from my inverter to the batteries, one wire in conduit to the rear bedroom outlet from inverter) I had to drill a sizable hole through the floor and out the bottom of the RV. I found that if I use a 1 5/8โ drill bit it makes a nice size hole and then I use one of these 1-1/2 in. x 6 in. White Plastic Flanged Strainer Sink Drain Tailpiece Extension Tubes (https://www.homedepot.com/p/Everbilt-1-1-2-in-x-6-in-White-Plastic-Flanged-Strainer-Sink-Drain-Tailpiece-Extension-Tube-C9800/205154040) cut so that it sticks out about an inch out the bottom of the RV. I could glue this in place and it provides for a smooth exit out of the bottom of the RV (instead of rubbing on the metal undercoating that was drilled through. Once all the wires were done and the system was complete, I stuffed some steel wool inside this tubing so that it was about halfway between the floor and the bottom of the RV, and then I filled the rest (top and bottom) with some sealant foam (like this: https://www.homedepot.com/p/Loctite-TITE-FOAM-Window-and-Door-12-Fl-oz-Insulating-Spray-Foam-Sealant-2260115/302135916?ITC=AUC-62427-23-12140). This sealing (and steel wool) should make it rodent proof and air-tight.
Here is a fairly complete list of components:
- Two 250w residential panels (https://store.santansolar.com/product/santan-solar-t-series-250w/)
- Two 15amp inline MC4 fuses (Amazon.com: Renogy 15A Male and Female Connector Waterproof in-Line Fuse Holder w/Fuse, Black: Garden & Outdoor)
- One Y-branch MC4 parallel wire connector
- 40โ of 10AWG wire with MC4 connector ends
- Two 6โx16โ screens from Home Depot to re-cover the refrigerator screen that I cut to gain access to drop the wires without having to pull the refrigerator (Gibraltar Building Products 14 in. x 6 in. Galvanized Steel 2-Way Reversible Vent-TW146-1/8 - The Home Depot)
- 5โ of electrical conduit to run behind the refrigerator to keep the wires away from the hot components of the cooling unit of the refrigerator
- Zip tie mounts and zip ties to keep the wires tidy along the way (https://www.amazon.com/gp/product/B07M69LTLJ/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1)
- 20โ of 2/0 cables to cut and double up and run two pairs from inverter to batteries (https://www.amazon.com/gp/product/B07FZWBKNZ/ref=ppx_yo_dt_b_asin_title_o07_s00?ie=UTF8&psc=1)
- Bag of copper lug connectors for making custom length cables (https://www.amazon.com/gp/product/B08R6TX3XM/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1)
- Crimper tool for making custom length cables (https://www.amazon.com/gp/product/B07V6V7XZC/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1)
- 5 tubes of Dicor self-leveling sealer
- 1โ plastic tubing and a small hose clamp (to apply Dicor BEHIND the Z-brackets)
- Two 1-1/2 in. x 6 in. White Plastic Flanged Strainer Sink Drain Tailpiece Extension Tubes
- Steel wool and foam sealant (to seal up any openings made in the bottom of the RV)
- Romex, 3 junction boxes and outlet receptacles and cover plates.
- Plenty of electrical tape
- 30 amp MPPT solar controller (https://store.santansolar.com/product/epever-3210-30a-mppt-solar-charge-controller/)
- 2000w Pure Sine Wave Inverter
- Two 40amp resettable fusesโฆone between solar panels and the controller, and one between the solar controller and the batteries. These are located right next to the solar controller so I can effectively enable/disable the solar anytime I need (https://www.amazon.com/gp/product/B07KF2PV6V/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1 )
- Misc: Screws, washers, nuts, bolts
I didnโt really keep track of how many hours this project took me. Probably ~20 hours, which included lots of trips back and forth to Home Depot for misc items. I had fun (mostly) doing it, and learned a lot. The good news is that Iโm putting another 400w solar system on my nearly identical Majestic 28a. While I was performing this current 500w install, I bought double the supplies/parts knowing that I have another one to do. I suspect Iโll be able to install the next solar system on my other RV in probably half the time now that I know all the tricks (and have all the components on hand). This was my first solar project and Iโm very happy with the results. Canโt wait to head off-grid somewhere soon!
Happy Camping all!
Chris
1.5yr Update, Test:
I haven't had to do a single thing to my solar or batteries (except check occasionally for water level on the lead acid batteries). The batteries are kept charged and when boondocking I've never even gotten below 50% on my 200AH battery bank.
Just for fun, and out of curiosity, I decided to do a charge test with my solar/batteries. Yesterday evening I ran a small 120v heater through my inverter to discharge my batteries down to 35% (65AH remaining out of 200AH). I disconnected my solar panels (via convenient breaker) and I let the batteries sit overnight. Today at noon I went to my RV and turned on my solar to see what sort of amps I could get flowing into my batteries. There were two reasons I wanted to do this. First, I wanted to see what the maximum solar amps I would get out of my flat mounted panels flowing into my batteries, and secondly I wanted to check the impact of having DIRTY solar panels (I haven't cleaned them ever...only time they get clean is when it rains).
Here was my test...
Conditions: August 12th, 12:45pm in the afternoon. Bay Area, CA. Sunny, cloudless, 80 degrees. Sun high in the sky but definitely NOT directly overhead. Flat roof mounted panels (two 250w residential panels). Battery at 35% SOC (65% discharged). 30amp MPPT solar charge controller.
This is how dirty they both were:
Here is an image of the dirty vs clean panels:
Before cleaning panels:
25v from panel (measured via solar charge controller)
12.0amp from panel(measured via solar charge controller)
23.6 amp into batteries (measured by Aili battery monitor)
Battery voltage via Aili monitor: 12.7v
After 1 panel clean:
25v from panel (measured via solar charge controller)
13.3amp from panel (measured via solar charge controller)
25.2 amp into batteries (measured by Aili battery monitor)
Battery voltage via Aili monitor: 12.7v
After both panels clean:
26v from panel (measured via solar charge controller)
13.9amp from panel (measured via solar charge controller)
27.3 amp into batteries (measured by Aili battery monitor)
Battery voltage via Aili monitor: 12.7v
Conclusions:
- 27.3 amps out of a 500w solar system seems quite reasonable to me. Thoughts?
- The difference between clean panels and dirty panels was 3.7amps (15.7% improvement).
- My EPEVER 3210 30A MPPT Solar Charge Controller seems to be doing a good job converting extra voltage from the panels into current to the batteries without much loss.
One Question: Is it reasonable to be getting 25-26v from my solar panels? Here is the spec sheet:
Maximum Power: 250w
Open circuit Voltage: 37.6v
Voltage at Pmax: 30.3v
Short Circuit Current: 8.85a
Current at Pmax: 8.27a
Regarding Voltage as seen at my solar charge controller:
The wire run from my panels to my solar charge controller is about 35' and is 10AWG wire. Using an online voltage drop calculator with 35', 10AWG, 30v, and 16amps, it says my voltage drop should be 1.3v (4.4% loss, which seems fine to me). Do you think I am not seeing closer to 28v at my solar charge controller because the sun is not directly overhead? Just curious.
As mentioned in my original post, I only really needed/wanted 200w of solar but ended up putting up 500w (because it was so inexpensive with used panels). I'm not trying to squeeze more charging out of my system as it is overkill for my needs already. I just find it fun to tinker around with it. Solar is fun and addictive!
Happy Camping!
Chris
I haven't had to do a single thing to my solar or batteries (except check occasionally for water level on the lead acid batteries). The batteries are kept charged and when boondocking I've never even gotten below 50% on my 200AH battery bank.
Just for fun, and out of curiosity, I decided to do a charge test with my solar/batteries. Yesterday evening I ran a small 120v heater through my inverter to discharge my batteries down to 35% (65AH remaining out of 200AH). I disconnected my solar panels (via convenient breaker) and I let the batteries sit overnight. Today at noon I went to my RV and turned on my solar to see what sort of amps I could get flowing into my batteries. There were two reasons I wanted to do this. First, I wanted to see what the maximum solar amps I would get out of my flat mounted panels flowing into my batteries, and secondly I wanted to check the impact of having DIRTY solar panels (I haven't cleaned them ever...only time they get clean is when it rains).
Here was my test...
Conditions: August 12th, 12:45pm in the afternoon. Bay Area, CA. Sunny, cloudless, 80 degrees. Sun high in the sky but definitely NOT directly overhead. Flat roof mounted panels (two 250w residential panels). Battery at 35% SOC (65% discharged). 30amp MPPT solar charge controller.
This is how dirty they both were:
Here is an image of the dirty vs clean panels:
Before cleaning panels:
25v from panel (measured via solar charge controller)
12.0amp from panel(measured via solar charge controller)
23.6 amp into batteries (measured by Aili battery monitor)
Battery voltage via Aili monitor: 12.7v
After 1 panel clean:
25v from panel (measured via solar charge controller)
13.3amp from panel (measured via solar charge controller)
25.2 amp into batteries (measured by Aili battery monitor)
Battery voltage via Aili monitor: 12.7v
After both panels clean:
26v from panel (measured via solar charge controller)
13.9amp from panel (measured via solar charge controller)
27.3 amp into batteries (measured by Aili battery monitor)
Battery voltage via Aili monitor: 12.7v
Conclusions:
- 27.3 amps out of a 500w solar system seems quite reasonable to me. Thoughts?
- The difference between clean panels and dirty panels was 3.7amps (15.7% improvement).
- My EPEVER 3210 30A MPPT Solar Charge Controller seems to be doing a good job converting extra voltage from the panels into current to the batteries without much loss.
One Question: Is it reasonable to be getting 25-26v from my solar panels? Here is the spec sheet:
Maximum Power: 250w
Open circuit Voltage: 37.6v
Voltage at Pmax: 30.3v
Short Circuit Current: 8.85a
Current at Pmax: 8.27a
Regarding Voltage as seen at my solar charge controller:
The wire run from my panels to my solar charge controller is about 35' and is 10AWG wire. Using an online voltage drop calculator with 35', 10AWG, 30v, and 16amps, it says my voltage drop should be 1.3v (4.4% loss, which seems fine to me). Do you think I am not seeing closer to 28v at my solar charge controller because the sun is not directly overhead? Just curious.
As mentioned in my original post, I only really needed/wanted 200w of solar but ended up putting up 500w (because it was so inexpensive with used panels). I'm not trying to squeeze more charging out of my system as it is overkill for my needs already. I just find it fun to tinker around with it. Solar is fun and addictive!
Happy Camping!
Chris
John&Joey wrote:
What was the logic for running so much wire on top of the roof vs plunging inside?
Has mostly to do with ease of installation (....and/or the fear of the unknown!). I don't really know much about how the roof and walls of the RV are designed and what space is in between and how easy/hard it is to route wires "invisibly" in the walls/ceiling. Because I knew I could do it, I routed the wires from the panel and shot them down the refrigerator vent.
And then punched through the bottom of the RV and routed underneath the RV (easy access) over to the driver side dinette.
~10' run on the roof....~10' drop from roof down to the underside of the RV...~15' run from underneath the refrigerator to the driver side dinette...and then about 4' punching back up into the RV under the dinette to the solar charge controller.
According to my calculations, I'm looking at a max of ~3.5% voltage drop (if the panels were at max output of 16 amps). 500w becomes 482.5w. Negligible.
-Chris
