Power Systems for Off-Grid Vacation Cabins: Page 5 of 5

Intermediate

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In an off-grid, part-time cabin, battery bank sizing and care are often more important than PV array size.
This off-grid cabin has solar water heating collectors and solar-electric modules.
This tiny house, occupied part-time, requires only a couple of PV modules to meet its electricity needs. A solar water collector provides domestic water heating.
This compact, modified sine wave, off-grid-only inverter is offered in 600 W and 1,500 W versions. It has a built-in 120 VAC charger for charging the battery bank from any AC source, such as a generator.
This multimode inverter can receive grid power and send out PV power, and can also operate in off-grid mode.
Nickel-iron batteries are an “old” technology that offers superior longevity, but also has efficiency and financial costs.
High-performance lithium-ion batteries are light and small, but require sophisticated charge management and are expensive.
Saltwater batteries are quite new to the scene but the industry is hopeful about their efficacy.
AGS units usually work fine—it’s other, less reliable parts of the system (like the generator and fuel supply) that cause many pros to discourage using them.
Though often less than desirable because of the noise and pollution it generates, a backup generator for battery charging during times of little sun can be a necessary addition.
The author’s family cabin, at 8,200 feet of elevation in the northern Colorado mountains, uses a small PV array to keep full-time loads running and batteries well-charged, even when it’s vacant.
Most inverter manufacturers and third-party companies offer remote system monitoring, but you’ll need always-on internet access at your cabin.

Unfortunately, there are a lot of “ifs” in the process, especially when no humans are available to intervene when (not if) things go wrong. My informal survey of remote, off-grid system installers here in the remote Colorado mountains match my own experiences: All of the various AGS systems from different inverter/charger manufacturers and third parties work equally well—it’s the generators themselves that are cantankerous. Dead starting batteries due to multiple failed starts can be caused by a generator that’s low on fuel, or low on coolant, or has low or dirty crankcase oil; by an owner who accidentally messes up the inverter AGS settings while trying to reprogram; if AGS settings are lost when the owner shuts down system for regular maintenance; a generator buried in snow, that overheats due to lack of ventilation; a wasp nest in the generator electronics box that shorts AGS circuitry...the list goes on. I prefer to keep things simple by reducing cabin loads to zero (or as close to zero as possible) when the property is vacant—and avoid AGS systems entirely.

Remote System Monitoring

If your vacation cabin location has internet service, installing remote monitoring equipment is often simple and inexpensive, requiring only a router that uses only a few watts and, possibly, an outdoor antenna. Most inverter and charge-controller manufacturers include data ports on their equipment that can talk directly to the internet via Wi-Fi, and third-party companies also provide this service. In most cases, you don’t need your own website to view your system data live from anywhere in the world—it appears on the company website after you log in. These services usually are free initially; after a year or two, a small yearly fee is charged.

If your only internet connection is broadband satellite, it gets more complicated, as the satellite dish and modem can draw from 50 to 100 W when turned on. For most systems, that draw is usually too large to leave on unattended for weeks or months at a time. Ham radio can also be used to remotely send data about the status of your home temperatures, power system, and battery bank SOC while using very little energy, as can satellite short-burst data transmitters. The sky’s the limit on remote system monitoring, if it fits your budget.

Plan Carefully, Then Go Remote!

Keeping a vacation cabin power system alive and well during extended absences is not difficult—it just requires pre-planning, careful component selection and using a thorough checklist before you button up. One last piece of advice: don’t forget to turn off the lights before you leave!

Comments (2)

Tonatopia's picture

I am currently in the USA from Australia. Back home, I use Victron Energy products.

Where can I get product from USA of Victron Energy for offgrid systems?

Michael Welch's picture
Hi there. You should be able to get similar products from any local renewable energy dealer. Or you can try the folks at Backwoods Solar.
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