Time will tell soon...

 

Below is a schematic drawing of our system showing the components and how they are interconnected. I arrived at this design after much research, many iterations and hours of online discussion.

 

The heart of any solar system is the batteries. I originally designed my system with 8 Battle Born 100A LiFePO4 batteries. One of my online mentors suggested that I consider using Victron batteries instead. The choice to use two Victron Batteries to provide the same capacity saved a little bit of battery weight and reduced a lot of component complexity and weight (disconnect switches, cables, etc.) These batteries aren't small or light - they weigh 125lbs each - but they take up a lot less space in my passthrough storage than 8 Battle Born batteries would have taken. As you can see from the picture below, they ship with very protective packaging. The batteries include an internal Battery Management System (BMS), have the ability to monitor individual battery/cell status via Bluetooth using the Victron Connect app on my phone and integrate with the Victron controllers to ensure optimum charging efficiency.

 

 

With a project like this, you can expect to receive a lot of boxes. Not all of these are solar parts, but most are. One lesson I learned is to open every box immediately and verify that it contains exactly what it is supposed to. I had several surprises where my solar supplier didn't pack everything they said was in a box. I didn't find out until weeks after the boxes arrived because I "wasn't ready" to use the content when the boxes came. At that point, I had to argue with the supplier about where the mistake was made and wait for the missing parts to be shipped causing delays in my project.

 

 

The first box I hung on the wall was the Victron Autotransformer. This takes the AC outputs from my two Multiplus inverter/controllers and creates a 50A output for my rig. The Autotransformer works with the Multiplus units to balance the load appropriately for the two circuits in my rig.

 

 

After the Autotransformer, I hung the mounting brackets for the Multiplus units. After I had wrestled them onto the wall, I realized I did not leave the recommended cooling clearance between devices and had to take them down and move the brackets. Oops.

 

 

Make sure you inventory absolutely everything, multiple times as you work on the project. It was at this point that I realized I had only ordered two of the three Victron Lynx distributor bus segments needed for my project and was also short some fuses. Oops. Another delay.

 

 

The wiring for the 50A AC circuits in the rig is 6/3+ground. Don't let anyone fool you, 6/3 cable is a pain in the a** to work with.

 

 

This is what the Victron Lynx bus and shunt look like with fuses before cables are attached. Note that each components bolts onto the component to its left. This made it relatively easy to add the third bus segment when it arrived. Unfortunately, the first segment I mounted to the wall was the rightmost segment. Obviously it had to come back off when I realized how they link so I could start assembling from the left.

 

 

I chose to make my own battery cables. With a 24V system, I was able to use 2/0 cable, which is easier to work with than the 4/0 I would have needed for a 12V system. It is important to keep all of the cables as close to the same length as possible. I used red and black heat shrink tubing to differentiate my +/- cables rather than buying different color cable.

 

 

Having a good quality cable cutter made for nice clean cable ends with minimal effort. My dad always suggested it was best to use the proper tool for the job at hand. Here's a (non-affiliate) link to this cutter:
https://craftsmancapitol.com/products/craftsmancapitol-premium-ratchet-cable-wire-cutter-wire-cutting-hand-tool 

 

 

The result, a nice clean cut cable end, ready to crimp!

 

This 5 US ton hydraulic crimper worked great for my 2/0 cables. You might need a beefier crimper if you have to use 4/0 cables (non-affiliate):

https://www.amazon.com/gp/product/B00HJXHX1K/

 

 

 

Make sure you have a decent heat source for shrink wrapping...

 

 

If you're doing any MC4 connectors, you'll need a crimper for that. I suggest this one (non-affiliate):

https://www.amazon.com/gp/product/B07C2N6CKM/

 

 

More to come...

-- Edited by karoleks on Tuesday 8th of September 2020 09:46:51 AM

This might be the most impressive post on this subject I've ever seen. I would like to offer some thoughts to help others with their decisions. A friend of mine, who is a solar fan, once told me that it costs a lot of money to camp for free ... Your post proves that point.


When we ordered our trailer, we made a conscious decision to not order an onboard generator, for several reasons, including:

1) They need to be "exercised" regularly, regardless if you need them for electricity, this is wasteful of gas. We "exercise" our generator whenever we move to run the AC units on the road ... keeps us from arriving and having a hot camper to deal with.

2) They're expensive to buy and, over the life of our camper, could use a significant amount of gas. No argument about the use of fuel.

3) Most campgrounds restrict the hours during which generators can be run. Those hours are usually the same as when your solar panels go away because the sun has set or not yet risen. Why would you use a generator in a campground?

4) I would rather have a lighter fossil fuel footprint than that afforded by the generator. This is not to discount your opinion ... it is a noble thought, but the manufacturing of solar panels and batteries use a LOT of natural resources. The whole "green" thing is a "something for nothing" shell game and the making of and the disposal of all the things that are needed to make "free" electricity is probably carbon neutral to a generator. Can't prove it, but that's my opinion. In our sticks and bricks we had a 10 KW solar system which really lowered our electric bill (we had net billing) ... but if you do the math, without all the federal and state subsidies we were just pre buying electricity. The break even was about 20 years, which interestingly is about the life span of solar panels.

All that said ... your system is very impressive and I am impressed with the quality and quantity of your post ... outstanding job.

Agree with Ron, a very thorough post. 

Ron, was your 10kW system grid tied with no battery backup?

If not then yeah I can see the 20 year timeframe and therefore harder to justify the expense.
For an RV however, if you take the cost of being in a FHU site at $40ish per night vs free boondocking with solar...
your payback time decreases dramatically the more you boondock.

The killer is the batteries, improperly used shortens their life and they are not cheap to replace either. Regular
LA, AGM or LFP. LFP has high upfront cost but lasts the longest but even they can be finicky.
Anecdotally, LFP does not like to be charged to 100% nor drained completely though you can do both,
but it will shorten its service life, same for AGMs or LA but the parameters will be different.
IN either case batteries get murdered by misuse. Cha Ching! Therein is the real expense of RV solar systems over time.
Panels are cheap now, in 20 years battery tech will lower the cost there too but for now, for many they are budget busters.

Steve, your system is certainly elaborate and likely far more that we intend for our planned application, we will follow along with interest.

Brian

-- Edited by BiggarView on Thursday 10th of September 2020 07:01:36 AM