It’s been quite a while since we installed solar panels on the roof, but we haven’t yet talked about what those panels are connected to. When we were trying to figure out how much solar we could get, we were also simultaneously trying to figure out the whole battery situation: how much power we need, how much of a battery bank is possible based on how much solar input we can get, what kind of batteries we wanted, and how much space the batteries would consume.
When we completed the solar, way back when, we left some wires dangling from under the headliner, ready to be plugged into whatever charge controller and battery we chose. The actual amount of power and batteries we get is limited by how quickly they can be recharged by the amount of solar that we managed to fit onto the roof in addition to the cargo boxes.
There is one thing that is always true when considering your solar and battery capacity: you can never have too much power. Instead of limiting yourself to a certain total wattage input, or certain total amp-hour (AH) capacity, just plan to buy the maximum amount of solar you can realistically fit on your roof (or ground deploy) and battery capacity to match, typically 1 amp-hour per watt (more watts per amp-hour will charge faster). Space will always be the limiting factor. If you end up having more power than you typically use, no problem, your batteries will last longer as they will have shallower discharge cycles. But if you end up having not enough power, your batteries will need replacing sooner and you’ll have to start strategically planning your power usage.
There are other options for charging, of course, but nothing will be as maintenance free, reliable, and as quiet as solar panels. Generators are noisy and require maintenance like oil changes, not to mention you are burning money (gas) every time you use it. Windmills would only be usable in non-stealth locations and require setup and must be taken down in high winds. Charging batteries from the vehicle alternator while driving is practical for urban vandwelling if you drive a lot, but there are potential problems here as well, like not having a long enough commute to charge them. And since urban vandwelling allows you live very close to your place of employment, which saves fuel and commute time, the batteries won’t charge much.
Since the solar we were able to fit on our roof equated to 270W (216W usable, assuming 80% efficiency), a battery bank of 200AH would couple nicely. Make no mistake, 200AH is not a large battery bank (in size or capacity). Now, consider that for the longest battery life, they should never be brought below 50% charge. We don’t have a whole lot that requires power (yet), so for the time being, 100AH of usable capacity is okay.
Space is at a premium in a small van, and it’s not just the batteries themselves that will consume it; charge controllers and inverters can be quite large depending on their respective abilities. Our past two truck campers, while not large dwellings, still had more space than our van for housing multiple batteries, charge controller (both solar and shore), inverter, multiple outlets, and all the wiring and fuses which make up a complete power system. The best solution for us was to select an all-in-one unit to cut down on the clutter.
We decided to get a Yeti 1250 from Goal Zero. I won’t get into all the details of the Yeti, but in addition to the space saving design, we chose this because of the expandability and serviceability. It is possible to connect additional external batteries to the unit as well as easily replace the internal battery when it starts to die. The Yet 1250 itself only has a 100AH AGM battery, so we did add an additional 100AH AGM external battery.
Sure, I know, you were probably taken aback when you first saw the price tag of this beast, and so were we. But considering the cost of acquiring all the individual pieces (especially when including MPPT and Pure Sine Wave features), it’s not too bad. Plus, we found it on sale for a few hundred cheaper, and two free Escape 30 folding solar panels, AND free shipping.
So far it has been working really well for us coupled with the solar panels on the roof. We have yet to deploy the two folding panels for extra charging (since we’re normally in the city, camping on the streets), but it’s nice to know we have a backup.
There’s only a couple things that I’d like to see improved, if they were to update it. First, a higher capacity charge controller (solar and shore). Currently, it has a maximum input of 240 watts, which I think is okay, but would much rather see a 400-500 watt input. The shore charging solution is just a power brick, much like a laptop would have, which is limited to 78 watts and is extremely (s)low. Second, support for lithium-ion batteries. For this, it would need a much more robust battery management system, which would drive up cost, but there would be a huge weight savings as well as capacity gain. Lastly, I would like it to have a real “fuel gauge”. It currently just shows capacity by measuring voltage, and it’s a really bad implementation at that. It only shows 20% increments without even displaying the actual voltage. A true battery monitor, much like the well known TriMetric, would be far and away better, but it would also drive up cost. If it had all those improvements though, I’d have no problem paying a higher cost.
I suppose there is one last detractor to this unit. If any of the electronics in it fail, there’s most likely no way to repair or replace them. It probably means buying a whole new unit… Here’s to hoping that the durability and longevity of our Yeti 1250 will not disappoint!
For the last six months or so, 200AH of capacity and ~250 watts of solar has been more than enough to power everything we could throw at it (excluding an electric space heater). However, we’re currently looking into possibly connecting this to our vehicle charging system (alternator). If/when we do that, we’ll most likely try to stuff two more AGM batteries under the hood of the van, replacing the single (small) starting battery currently there. If successful, we’d then have ~400AH of capacity and an additional charging method. And at that point, our limited solar input would have trouble recharging 200AH (50% depth of discharge) per day if we used that much power frequently, and, as said before, space for more solar panels is an issue.