2012 Update: This post was written based off our last RV – a 17′ Oliver Travel Trailer that was designed for being off grid. After 3 years of full time travel in the Oliver, in June 2011 we moved into a 35′ vintage bus to create something more versatile. We are in the process of designing an off-grid able, high-tech, home & office on wheels that is run off entirely electric and diesel (ie. no propane). We are experimenting with Lithium Ion batteries, and our bank is sized to run our air conditioner. We’ll soon add a solar array to the roof. And we are well on our way to our Propane Free Goal. If you’d like to follow along – please use the RSS subscribe feature over there —->.
It seems like every week we get an email or two asking us for more details about our solar RV travel trailer setup, what components we use, what things we run off of solar, and how well being solar powered is working for us overall.
We get so many questions that it seems like a good idea to try and answer them all in one place. So here goes:
What are the specs?
Our solar electrical system consists of:
- 2x AM100 100-watt Solar Panels – These two panels are bolted together on the top of our roof, giving us 200 watts of sun harvesting capability. Our roof mount is technically capable of being tilted, but since we don’t have a ladder to easily reach our roof to make adjustments we have kept our panels perpetually flat – sacrificing some efficiency for a lot of convenience.
- 2x Lifeline GPL-4C 6V AGM Batteries – These two “golf cart” style batteries provide us with 220 amp hours of overall battery storage capacity. AGM-style batteries cost more, but allow for faster and more efficient charging, and they do not require any maintenance.
- Blue Sky 2512iX Solar Boost Charge Controller – A fabulous MPPT-capable charge controller. For more details why we selected this controller, read our solar charge controller options post.
- Blue Sky IPN-ProRemote Battery Monitor – A real battery battery monitor that tracks amps in/out (and not just the battery voltage) is essential to efficiently using solar power. To learn more, check out our RV battery monitoring post.
- Xantrex Freedom 458 Inverter / Charger – The inverter / charger we selected can provide up to 2000 watts of AC power from our batteries when we need it, and when we are plugged in to shore power or our generator the 100 amp charging circuit can rapidly top off our depleted batteries much quicker and more efficiently than any trickle charger.
Did you install the system yourselves?
Chris did the entire solar conversion on his old 16′ Tab trailer himself, and we had been planning to do the work gutting the electrical on our next trailer to bring it up to our standards. But the great folks at Oliver Travel Trailer were willing to work with us to customize our new trailer exactly how we wanted it, so Chris researched and worked out the specifications on our solar system for our Oliver, right down to the gauge wiring.
The Oliver crew then procured, fabricated and installed our system (we were onsite for some of the installation and assisted) as part of our custom build. They even went so far as to make some modifications to their overall trailer design to accommodate our desires for maximum solar space on the roof, such as moving the A/C and vent fan back further to make more space for the panels.
Oliver now offers the system Chris designed as a standard package, and they have sold several units with the “technomadia package” using the same components as ours.
(And no, we don’t get kickbacks…)
What would you do differently?
Overall we have been extremely happy with most of the components we selected.
If we were building the system from scratch we would once again investigate every new possibility for more solar panel wattage and battery capacity, and the one major change we would make would be going with a sine-wave inverter / charger rather than the modified-sine-wave Freedom 458.
(Our 24″ monitor makes a faint whine when plugged into modifed-sine-wave power, even when it is turned off…)
What all can you run off the solar?
We can run all of the following off our solar power:
- Ceiling Vent Fan
- 12v small oscillating fan
- 2x Macbook Pro 15″ Laptops
- 1 Mac Mini (our trailer’s media and backup server), plus attached external drives
- Cradle Point ctr350 Router (converts our Sprint aircard to wifi)
- iPhone and camera battery chargers
- 24″ Dell Ultrasharp Monitor (via the inverter)
- Electric jacks/levels
- Water pump
- Furnace fan
- Cellphone booster system
- Small single serve smoothie blender (via the inverter)
We have optimized our systems so that nearly everything can run directly off of 12v power, allowing us to mostly avoid needing to turn on the inverter. The only things which we are unable to run directly off of 12v is our 24″ LCD monitor, and our small blender. The inverter has a bit of a power overhead just being on, so we minimize our reliance on it as much as possible.
Now.. we don’t run all these things all the time, mind you.
What don’t you run off solar?
Our refrigerator can run off 12v power, but it’s incredibly inefficient in this mode and it would quickly drain our batteries even on the sunniest of solar-producing days. Propane refrigerators like ours cool by producing heat, so it is most efficient burning propane when we’re off-grid, or 110v when we are plugged in.
It is also essentially impossible to power an air conditioner off of a solar system – the demands of even a small 1000-1500W air conditioner would require a huge expanse of solar panels, and massive banks of batteries to provide for even a few hours of air conditioning per day.
When we’re off-grid and really need it, we have a small 2000 watt Honda EU2000 generator converted to run off propane that will run our air conditioner. Our furnace (aside from the fan) and hot water heater are also propane powered.
We left the microwave/toaster oven option off our unit, though technically our inverter would be large enough to power it. But even though we could, running a microwave for even 15 minutes a day would impact our battery life, and honestly, it’s not our style of cooking anyway. We greatly appreciate the extra pantry space that decision afforded us.
How have you optimized your systems to run off solar?
All our our lights are converted to LED. This is a fairly easy switch to make, and we used LED Wholesalers to find replacement bulbs for our existing fixtures. We spent about $200 to switch all our bulbs out – pricier than standard bulbs, but so worth it for the power savings. We can turn all our lights on, and combined they use less power than a single halogen bulb previously did.
We have 12v MacBook power supplies from MikeGyver and HyperMac for our MacbookPros, that allow us to run our laptops without the power overhead of the inverter needing to be on. And we use a 12v power supply from Carnetix for our Mac Mini.
How long can you depend on solar power only?
Summer? Winter? Shade? Clouds?
We designed our system with a goal of enabling a full day of computing (8-12 hrs) for both of our Macbook Pros, plus using the lights, vent fan, and occasional water pump use.
With moderate use of our technology, we can easily go several days on end without even thinking about power much. During the summer with daily full sun, we have lasted as long as 12 days completely off grid without needing to top off with our generator – and we probably could have lasted much longer.
More typically, we tend to go 3-6 days at a time without much concern, providing we’re not in the shade or there aren’t overly overcast days.
If we are trying to make our batteries last, it is important to pay close attention to our batteries and how quickly we are draining or charging them. We ran a series of tests on every individual electrical item we own in various states of usage to know exactly how much power everything draws, so we can optimize our usage as needed
Our BlueSky battery monitor is absolutely essential here – it gives us a real time indications of our power usage, which keeps us very in tune with our system.
When we are trying to maximize our efficiency and off-grid stamina, we do need to be conservative with our power usage. We keep our power consumption to a minimum, and reward ourselves at night with a movie on the ‘big screen’ if we’ve ended the day with a good power score. Our goal is to always keep the batteries at above 50% capacity to ensure their health. Generally we can charge the batteries around 20% in a good day of moderate use and sunshine, so anytime we start creeping below 80% at night we know we are likely to soon need an alternate source of energy to top us back off.
Are you off-grid all the time?
We stay in a wide variety of places – and we have our solar system to increase our options, not to depend on it completely. Our ability to run completely off solar is dependent upon the weather and access to a clear sunny sky. In the winter, with shorter days, we tend to need to be plugged in more. If we’re parked at a friend’s house in partial shade or at a shady campground, we’ll also usually need a little help power wise.
And if we encounter a string of heavy overcast days, we can’t rely strictly on solar either.
As our batteries also charge off our tow vehicle’s alternator as we drive (and yes, the solar panels continue to top off the batteries as we drive too), our transition days tend to be unplugged – as we have plenty of power to keep us computing overnight. Even if we have no sun at all, a full battery charge can keep us going at least two days without needing topping off. And when in major transitions, such as from Washington DC to San Francisco last summer, we can go a couple months without ever plugging in. Days on the road tend to provide lots of sunlight for the panels, as well as plenty of hours charging off the trucks alternator.
It’s really difficult to give an estimate of how much time we spend plugged in versus not, just because there really is no ‘typical’ in our lives. For example, we may choose to stay in a major city – such as San Francisco last year – for a couple months, where it makes more sense to get a monthly RV space with power included.
But even when we are plugged in, we sip power. The last time we had metered electricity, we used about $20 worth of electricity a month – and that was not being conservative with our usage at all.
Do you consider your solar system adequate enough?
We wouldn’t want any less than our current battery capacity and panel size, and while more of both would be nice, it is not essential.
A good rule of thumb is to target 100 watts of solar and 100 amp hours of battery per person, minimum.
After almost a full two years of relying on our current system, our solar endurance has certainly never been much of a limiting factor, and having solar has given us quite a bit of flexibility. We certainly couldn’t imagine living without it.
We are looking at potential future upgrades in our battery capacity, as that is more of a limiting factor or us than anything else. If we had larger batteries we could bank more of the energy we collect to get through overcast days. We’ve also pondered adding more solar panels on top of our Tundra’s camper shell, and perhaps an additional battery bank in the truck bed, now that we have more flat surface to play around with.
But given that we don’t really feel we’re lacking, these upgrades are not a high priority.
Once you’ve had solar, traveling without feels limiting and uncivilized.