Part 3 – Results, lessons learned and component list with pricing
I had to work the next day, but when I tested the system the following weekend, I saw a max of 26.2A going into batteries that were just 3% drained by heating a cup of water in the microwave for a few minutes.
Interestingly, this current is a little under what my brother’s solar calculator ( http://where-rv-now.com/Notes/Solar/#Calculator ) comes up with as the theoretical maximum for my panels on the date they were measured. I think that means the system is working pretty well.
If we assume that the calculator is accurate ( now that we have a number that seems to match ) this means that my panels will, on an appropriately sunny day, put out my goal of 100Ah or better until mid November in any latitude I’m likely to visit at that time. Actually, if I’m that far North at that point in the year, I’ll be looking for shore power for a heater.
As for the lessons learned, well, I didn’t cover this much in the planning post, but I had originally seen the 3024iL listed as a 40A controller, which it kind of is under certain conditions. So, I had originally planned on purchasing four 160 Watt panels ( rated at 9.6A Short Circuit each ) for 640 watts, rather than the 540 I ended up with.
However, once I got the controller in hand and read the manual, I discovered that the 40A rating is only the OUTPUT side of the MPPT controller, and only when the input side is using 12V panels going to a 12V system. Under all circumstances, the input side is limited to 30A.
The controller can take 24V input, but then maximum power is limited to 400W.
This meant that I couldn’t use the four 160’s I had originally planned, either in series or in parallel. So I cut back to three 160W panels and added a 60 Watt to round my output to the controller maximum wattage at 12V of 540W.
The lesson: If you’re doing the planning and install yourself and you don’t have extensive experience with this stuff, you need to hit the internet, download the MANUAL ( not just the spec sheet ) and READ IT. Particularly if you’re operating anywhere near the limits of the equipment.
The good news is that I did eventually read it before I ordered my panels and so the results I got are still within my original goals, even if they’re 100W down on my first plan.
Issue 2: The installation required something like a dozen trips to the hardware store for little fiddly bits that I didn’t realize I needed until I actually tried to assemble the whole deal. 2 tubes more sealant than I had figured, stainless hardware, butt connectors, more cable lugs after I crimped two of them poorly, that sort of thing.
The lesson: unless you live RIGHT NEXT TO hardware store and an auto parts store ( a good place for high power battery connectors and stuff ) get extras of almost anything that you need multiples of, can be thought of as “supplies” and isn’t very expensive. $30 worth of that kind of stuff before I started would have saved me a weekend of putting the installation off because I didn’t have everything and $20 in gas running to the hardware store in the middle of the job.
Issue 3: The job took way longer than it sounds like in my description. Just running the wiring around on the underside of the RV took most of a week of after work labor crawling around by myself under the RV. After that it was most of two days assembling the panels and getting everything installed on the roof, since there were complications with the roof vent installation that I didn’t cover here.
The Lesson: Guess how long it’ll take and double it.
The complete parts list and costs:
|Three 160W panel kits||$1,080.00||AM Solar|
|Roof Combiner box||$72.00||AM Solar|
|35′ 4/2 cable||$175.00||AM Solar|
|10′ 10/2 cable||$25.00||AM Solar|
|3 cable seal||$9.00||AM Solar|
|4 4AWG lugs||$4.00||AM Solar|
|Four tubes sealant||$30.00||Amazon|
|10 tinned copper lugs||$10.00||Amazon|
|3M VHB tape 3/4″||$20.00||Amazon|
|Renogy Z brackets||$13.00||Amazon|
|50A circuit breaker||$29.00||Amazon|
|High current switch||$24.00||Amazon|
|Plumbing vent kit||$6.00||Amazon|
|60W solar panel||$105.00||Amazon|
|3024iL and temp sensor||$275.00||WeGo Solar|
|Cable ties||$6.00||Home Depot|
|Nylon cable holder||$2.00||Home Depot|
|Stainless bolts||$6.00||Home Depot|
|Silicon sealant||$4.00||Home Depot|
|Expanding foam||$6.00||Home Depot|
|5A fuse holder||$2.00||NAPA auto|
|15′ 16/2 wire||$10.00||NAPA auto|
|Crimp connectors||$4.00||NAPA auto|
|Self Tapping Screws||$2.00||Home Depot|
Note: The Solar Panel kit from AM solar included the panel, mounts, 15’ of 10/2 wire, cable ties and cable tie mounts, VHB tape.
AMSolar was very helpful, answering a bunch of questions or confirming the decisions I had made. They also helped to make sure I got all of the specialty pieces I would need in one order. I would definitely order from them again.
Amazon is tough to beat for cheap prices and fast, cheap shipping, but you get almost zero support, so it can be tough to put together a package without any missing bits. Still, if you had the right installation, you could put together a 400W MPPT system from Amazon for about half what I paid for my 540W one, though you’d have to make some compromises.
In Conclusion: Over the course of a few months of planning and ordering, followed by a couple weekends of messing about on and under the RV, I successfully installed a high quality 540 MPPT solar system on my RV for just under $2000. I’m pretty happy with that.
Thanks for reading. Feel free to email with questions: airmon at gmail dot com.
Note – Pictures of many of the components and the installation are at https://plus.google.com/photos/101533552838802518081/albums/6002206624346422593?authkey=CNKhpNigsd_DpgE
Three 160W panel kits $1080.00 AM Solar
Roof Combiner box $72.00 AM Solar
35′ 4/2 cable $175.00 AM Solar
10′ 10/2 cable $25.00 AM Solar
3 cable seal $9.00 AM Solar
4 4AWG lugs $4.00 AM Solar
Shipping $58.00 AM Solar
Four tubes sealant $30.00 Amazon
10 tinned copper lugs $10.00 Amazon
3M VHB tape 3/4″ $20.00 Amazon
Renogy Z brackets $13.00 Amazon
50A circuit breaker $29.00 Amazon
High current switch $24.00 Amazon
Plumbing vent kit $6.00 Amazon
60W solar panel $105.00 Amazon
3024iL and temp sensor $275.00 WeGo Solar
Cable ties $6.00 Home Depot
Nylon cable holder $2.00 Home Depot
Stainless bolts $6.00 Home Depot
Silicon sealant $4.00 Home Depot
Expanding foam $6.00 Home Depot
5A fuse holder $2.00 NAPA auto
15′ 16/2 wire $10.00 NAPA auto
Crimp connectors $4.00 NAPA auto
Self Tapping Screws $2.00 Home Depot