We spent last week attending the Xscapers Annual Bash 2020, which turned out to be a great experience where we met a lot of great people and learned a lot of new things. One of the constant discussions I found myself getting into regarded solar, and more specifically the places that you can go once you are no longer tied to the power grid.
There are a lot of people we talked to who installed solar and stopped staying at parks altogether – dropping their annual camping fees close to or entirely to zero. I don’t see that happening for us, but can easily envision solar supplementing power we pull from the grid, and serving as a means to stay in places that we otherwise would be unable to.
Since starting our full-time journey on Oct 20, we’ve spent $2,932.48 in camping fees. That works out to $31.87 a night, or $956.24 per month and around $11,500 projected for the first year. If we break up our year between dispersed (free/low-cost) camping, lower cost state park camping (since we no longer require 50A service), and private FHU sites (with reduced electrical bills), we will eventually break even on cost savings. Whether that happens in one, two, or three years depends on how our camping habits change, but if we reduce our nightly spend by half, it’ll pay itself off in around two years – less time than we’re currently planning on being out here.
Our cheapest month was November, which was $350/mo+electric, but our electric bill turned out to be $300.38. We made liberal use of electric heat in New Mexico, expecting the electric bill to come in much closer to the $100 deposit we put down when we first arrived. It was a little bit of sticker shock, but we paid the bill and went on our way. After talking to people at the bash, that seems fairly normal. I can only imagine summer in Texas or Arizona.
Regarding costs, I’m not looking at solar purely as a way to save money. That is one of the major perks of having it, but not necessarily the largest driving factor. We took to the road for freedom, and there are a lot of restrictions for us when we require full hookups wherever we go. We want to be prepared and ready for anything, and aside from the limitations we have for Internet (required for work) and the sheer size of our rig, want to eliminate all restrictions possible.
Solar can run the gammut from a couple collapsable panels that directly fill 12v batteries that can only supply power to the 12v side of your rig, to residential style deployments that give you an enormous amount of flexibility going down the road. As per the norm, we never start small, and pulled the trigger on the latter today.
A 40′ rig has a lot of avenues for power consumption, the largest (non-HVAC related) being our residential refrigerator. We made a big deal of swapping over to a residential unit from the factory RV fridge, and have absolutely no regrets. Massive (comparable) power consumption aside, the residential fridge is one of the best upgrades we’ve made. We initially installed a 1000w Xantrex MSW inverter to power the fridge, which kept depleting the group 27 battery we used and going into fault mode, so we recently upgraded to an AIMS 3000w inverter and 4x6V GC2 batteries for a much larger amount of energy storage before heading to Lake Havasu for the week. The inverter is only installed on a single circuit, capable of powering our refrigerator, TV (which we didn’t power on), HTPC (which we didn’t power on), router, and coffee pot (used for <5min/day) and we were depleting the batteries enough on a daily basis to require the generator to run around four or five hours to charge them. If we were powering the entire rig, we would have been in trouble. All said and done, we ran through over 40 gallons of propane last week with two cylinders that only hold around seven each. Most of that was for the generator, while a little was for the furnace and cooking.
Mid-week, I bought and installed a Victron meter to measure power consumption and found we were using around 2.2KwH per day. The EnergyStar label on our fridge estimates 613KwH per year, which works out to be around 1.7KwH per day, plus any inefficiencies we have in the DC-AC inversion process, and the minimal lights/other items that we had on. The DC system was powering our water pump, furnace fan for probably a few hours a night, just a few LED lights for a few hours per day, and cell chargers. I did use the AC system to keep my laptop charged up.
With that baseline number of around 2.2KwH, I could start engineering a system with some broad assumptions for the rest of our utilization. That also means it was time to set some goals. I assembled a pretty lofty wishlist:
- Whole RV power – no unpowered circuits, no unpowered outlets, microwave, washer/dryer, A/C and heat all included in the system
- Enough reserve capacity to run at least a day without sun
- Supplement the shore power with battery power so that we can comfortably camp on 15A, 20A, 30A, or 50A electrical hookups (current configuration of the rig requires 50A to achieve bullet #1)
- Charge batteries as quickly as possible from the generator – ideally an hour or two from empty to full
- Don’t add a ton of weight
We were fortunate enough to be near a couple nice neighbors at the really who both had Victron setups, and after seeing those the decision to go with Victron was easy. They seem to be the most popular brand for the more sophisticated solar deployments, and I’ll elaborate why in future posts. Among other things, they provide an amazing insight and monitoring pane for all of your Victron equipment so that you know exactly what the state of your entire system is.
Bullets #1and #3 are addressed by the Victron MultiPlus units for most RVs. The most basic/common setup is a 12V Victron 3Kw inverter powering one leg of your 50A service, and rearranging your breaker panel so that the loads you want to run off solar are all on that leg. I did not want to do that. If that isn’t your thing, you can add a second MultiPlus on the other leg and each MultiPlus will provide power to basically half of your breaker panel. I decided to start with this and put together a basic plan that a lot of RVers go with – dual MultiPlus units, a handful of 12V LiFePO4 batteries, and some panels on the roof. I called Victron with these plans and they sent me to Arizona Wind and Sun, where an engineer reviewed my plans and shared some other options with me.
After probably seven different iterations and several days of collaboration, we decided to ditch the 12V system most people go with and step up to a 48V system. That moves us from the MultiPlus to the Quattro line of inverters. So instead of the standard MultiPlus units, I’m adding two Quattro 48/3000/35-50 units which are responsible for inverting DC to AC, as well as charging the batteries. With a 48V system you gain a lot of efficiency over a 12V system, can access LiFePO4 batteries at a lower cost per KwH due to the system using the same batteries you’d find in more commercially viable residential/commercial systems, and can use smaller conductors because you are dealing with less current. The 48V adds some complication to an RV because you still need 12V to power many components, so we’re opting to keep two GC2s for the 12V system and keep them topped up with 70A power through a pair of 48V DC to 12V DC 35A converters. And since we’re charging the 48V system off the inverters, and the 12V system off the 48V, we can return the converters we’ve posted about recently.
Where most deployments use the two inverters to each power half of the breaker panel, we aren’t fully achieving the goal of bullet #1 yet. If the load exceeds 2.4kW on one leg while relying on inverter power, then the inverter shuts down due to overload. This seems to be pretty rare in actual usage based on my discussions with people, but you can (mostly) solve the issue by using an AutoTransformer between the two inverters and the panel so that the load for the whole panel is load balanced between the two inverters. That means that we would theoretically be able to pull the combined 4.8kW of inverter capacity on one leg of the 50A service, which is getting pretty close to a realistic shore power experience without stepping up to insanely powerful inverters. The only limitation to the AutoTransformer in this setup is that the difference between the current draw on the two legs can only be 32A (around 3240w) – a limit I don’t see how we could possibly hit.
Moving to the 48V system made bullets #2, #4, and #5 more accessible. Since we can use residential/commercial batteries, we have a lot more choice than the 12V units that are designed to fit in standard automotive battery boxes. We ultimately chose to go with a set of three Simpliphi 3.8KwH 48V batteries in parallel. They are rated for 10,000 cycles at 80% DoD and come with a ten year warranty – twice the cycle count of the leading RV LiFePO4 brands and twenty times the cycle count of a deep cycle lead-acid battery. A quick break down of costs that made the 48V system make sense:
|Battery||kWh @ 100% DoD||kwH @ Rec DoD||Cycle Life||Weight||Weight per kWh @ Rec DoD||Cost (MSRP)||Cost Per Wh @ Rec DoD||Cost Per Wh over 1,000 Cycles|
|Battleborn 12V 100AH||1.20||0.96||5000||31lbs||32.29lbs||$949||$0.99||$0.19|
|GC2 6V 220AH||1.32||0.66||500||64lbs||96.97lbs||$150||$0.22||$0.44|
|Simpliphi 48V 75AH||3.80||3.04||10000||78lbs||25.65lbs||$2690||$0.88||$0.09|
The Weight per kWh @ Rec DoD shows us the physical density of the battery. Since we’re in a moving vehicle where weight matters, the lowest number is best. The Simpliphi wins by more than 6lbs per kWh. It would take 896lbs of GC2s or 294lbs of Battleborns to provide the same capacity as 234lbs of Simpliphi.
The Cost per Wh @ over 1,000 Cycles shows us the actual long-term cost of ownership of the battery. While the other batteries are far less expensive in the short term, the long term costs due to the shorter lifespans of the batteries are far more. This is a huge selling point that Battleborn uses to push their batteries over the GC2s, but the Simpliphi could use the same argument against Battleborn since it has twice the lifespan. They’re not really in the same market/class, though and wouldn’t make sense for a lot of RV deployments. We’re not using existing battery bays, so we were able to use these.
One of the guys I talked to at the bash had just invested $16,000 into a custom 1200AH (14.4kWh) 12V battery bank. That works out to $1.11/kWh. Three of these batteries retail for $8070, about half the price, but offer 11.4kWh or $0.71/kWh. That works out to be almost 44% cheaper per kWh.
Circling back to the initial topic in this section, the ideal DoD for three of these batteries (80%) yields 9.12kWh of capacity. Knowing that running next to nothing, and the power-hungry refrigerator, draws 2.2kWh, means that we have 6.92kWh of power remaining for a 24h period without any sun, shore power, or generator. I have to make some major guesses regarding the rest of our utilization, but that should give us ample buffer unless we’re running the AC or heaters for an extended period of time. A/C is still a losing proposition since our two AC units combined draw around 2.75kWh, meaning the run time for both would be 2-3 hours before depleting the batteries. We’ll have to stick to the cooler climates in the summer.
Moving on to the charging aspect, we can charge the batteries with shore power, solar, or generator. The Quattro units are actually very powerful chargers that charge the batteries at 4.03kWh combined. To fill a completely dead bank of three batteries, we would need to run our generator for a little under three hours. Two and a quarter if at 80% DoD. In order to maximize the charging from the generator we need another AutoTransformer between the generator and the two inverters, but the cost is worth it to minimize the generator run time – which is loud, inconvenient and costly due to propane usage.
Regarding solar, we are lucky to have a large unobstructed roof that can house several full-size residential panels. We’re going to go with six highly efficient 325w REC N-PEAK panels in two strings for a total of 1950w of solar. We’ll be using a SmartSolar 150/35 MPPT for each string. A quick solar calculator (plugging in Quartzsite, AZ) says we’ll probably range from 4.78kWh/day in January to 8.18kWh/day in June. It’s a moderately sized solar setup that should replenish our consumption on low-key, moderate temperature days.
And finally, we’re down to shore power. Looking back at my list, one of my goals was to be able to supplement shore power with the setup so that we can connect to lower-amperage shore sources. In the default configuration, these inverters will pass through shore power when connected and just keep the batteries topped off. You can flip this around and only use shore power to keep the batteries charged. This has several key uses:
- We can plug into 15A household circuits and have all the amenities of full 50A service, as long as we have sufficient energy stored in the batteries and/or are collecting sufficient solar. This opens up driveway camping at relatives and friends for us, as well as low-cost sites we would otherwise ignore.
- The same goes for 30A electrical service available at almost all older parks. Even a lot of fairly modern parks still only have 30A hookups and we’ve passed on lots of state parks because of this limitation. This opens them back up to us.
- Even when we have 50A service, if we’re paying our own electric bill, it can keep us from having a $300 bill like we did in New Mexico
We’re pretty excited about the possibilities this will open up for us. Here at the Grand Canyon we’re staying in Trailer Village which offers full hookups and great location, but also cramped sites and mediocre views. They have dispersed camping free of charge just a few miles a way, with amazing views, large sites, but no hookups.
Electric isn’t our only hookup issue, unfortunately, but I’m addressing the others in the same fell swoop. Right before we left to start this adventure, we discovered a water pump leak and replaced our nice water pump with a budget special that Amazon could get us overnight. It’s time to put a decent pump back in.
Our tank gauges offer poor resolution (dummy lights) and malfunction often despite our attempts to keep them clean. I’m going to install the TankEdge iSeries monitoring system which uses external sensors (outside the tanks, so they can’t foul up) and provides high resolution (percentages) so we should know exactly where our tanks are. It’s surprisingly inexpensive and we should have looked at this ages ago. We know we can go at least a week with conservative showering and no laundry, and have been using that knowledge to make educated guesses when not at full-hookup parks. Actually, this has led us to seek out exclusively full-hookup parks for quite a while, even before going full-time.
And finally, we’re still using the factory gate valves which have been problematic from day one. I pulled all the valves out and replaced the seals in them before we hit the road, but would like to replace them altogether. The upstairs black tank actuation cable recently broke and I was able to rig together a fix, but it no longer seats properly and I had to add a supplementary gate at the exit to catch the leak. The galley tank handle is in an odd location that requires you to reach under the slide to access it, while all the other handles are neatly contained in the water works area. Valterra makes electronically actuated valves that are much higher quality than the cable actuated valves that came with the RV, and would address both issues, so I’m going to swap those in.
So we’re addressing electric, freshwater, tank monitoring, and tank draining in the next few weeks. It’s going to be a lot of work but should change the way we travel. We’ll be able to add lower cost and zero cost sites to our repertoire and make up some of the cost, while accessing more desirable and remote sites that were previously off limits. Probably meeting up with other Xscapers at many of them, as they seem to do.