An Off-Grid Education: Page 3 of 3

Intermediate

Inside this Article

The Bowkers' garden and home.
Using local materials can reduce a home’s embodied energy. Wood flooring was locally sourced, and even the plywood for sheathing and subflooring came from mills only a couple of hours away.
The wood heater is fueled only until late morning, when the sun-tempered house then starts gaining heat from the winter sun through the southern windows.
A Danby refrigerator (no freezer) joins a host of energy-efficient appliances.
Though traditional country style, the home’s design takes advantage of some passive solar heating.
The PV array grew incrementally. Here, Jerry gardens beneath the pole mount prior to the most recent addition of modules.
A propane wall heater provides backup heating when solar gain is minimal and the wood heater is not in operation.
A SunDanzer DC freezer in the utility room provides efficient food storage.
A Whirlpool Duet horizontal-axis washer and propane-fired dryer make efficient work of laundry with less load on the batteries.
A Bosch propane on-demand water heater serves the home.
The OutBack VFX3524 inverter and balance-of-system components.
The eight Deka L-16s provide 740 Ah at 24 VDC.
System designer Kurt Nelson (left) with Sally and Jerry under the array.

Maintenance & Operation

The Bowkers have learned to maintain and troubleshoot their system, which makes it easier on Kurt, the solar electrician. “I do routine maintenance for the batteries, array, and generator,” says Jerry. “Once a month, I check the batteries’ electrolyte levels. Usually they don’t need a distilled water top-off, but when we’re using the generator a lot, I check them more than once a month.  We live in the snow belt, and when there is any snow cover on the arrays in the morning, I sweep them off—unless it is still snowing. The generator gets normal engine maintenance of regular oil changes. We adjust the array’s tilt angle seasonally, around the equinoxes.”

The home’s appliances are propane and electric, and include a Whirlpool Duet washer and propane-heated dryer. A kitchen range, a Bosch on-demand water heater, and an Empire wall heater also run on propane. With the most recent expansion of the PV array,  they also added a  diversion load of a tempering tank preheating their water to the on-demand heater. 

The refrigerator is a Danby electric model, without a freezer compartment. A high-efficiency SunDanzer DC freezer lives in the utility room. The Bowkers do not have a dishwasher or a microwave, but use a coffee maker, hair dryer, TV, laptop computer, printer, DC ceiling fans, and lots of electrical tools, such as table saws, drills, and sanders for house projects.

Wood is the primary heat source, with a centrally located wood heater. A propane wall heater provides backup when the house is unoccupied (and because homeowners’ insurance required it). Access to trees and Jerry’s love of making firewood allows him to “pay the heating bill” and maintain their woods at the same time.

The PV system’s modest size and seasonal sunshine mean that Sally and Jerry have to be acutely aware of their electricity consumption. “We check our battery state of charge several times a day, and don’t let it get below 70% before using the generator to recharge. We also check the weather reports to see when sunshine is forecast. Being aware of the system becomes an interesting part of our day,” says Sally.

If company is coming after dark, the porch lights go on about two minutes before they’re expected and then are off until the guests are leaving. Laundry and vacuuming are sunny-day activities. Like many off-gridders, when the sun shines, the couple finds ways to use the energy. “If I feel I must do a load of laundry or vacuum on a cloudy day and the batteries are quite high (above 85%), I will sneak in a load or do a quick vacuum run over the rug. It feels like that—sneaking. But we are very pleased with our system, and with how matter-of-factly it works for us.”

Lessons

Sally and Jerry love having renewable electricity, and believe that RE needs to become the common form of household energy. “We’re still amazed that it comes directly from the sun right above our house,” says Sally.

Their system has been reliable, but their installer Kurt checks in with them periodically. Sometimes their feedback means something more to him. Then he comes and adjusts, or makes recommendations. “Our experience in off-grid living,” says Jerry, “has made us feel strongly that off-grid solar is a viable option for non-technical people, if they have assistance available.”

Comments (6)

Bill Loesch_2's picture

Sally & Jerry,
Congrats on the successful adaptation of your RE system to your lifestyle (and vise versa). Would you care to share your philosophy with the microwave and using a separate freezer and fridge? Thanks, Bill

RMichael Curran's picture

Very nice house and RE system.

I'm wondering how their MX60 charge controller is holding up, what with 2100 watts of PV for a 24V battery system. Normally (I thought, anyway) for a 24V system the MX60 can't use more than about 1500 watts of PV (24V x 60A = 1440W). I'm asking because I have an MX60 and am currently considering adding PV but was going to go the added CC route, since I'm already near my MX60's max power input for my 24V system.

Thanks, great article.

Fred Golden's picture

If I where to upgrade my solar today, I would not spend $500 on a MPPT controller. The 40 amp Schneider controller at SunElec.com (a long time advertiser here) is only about $125. 250-300 watt panels can be bought for less than $200 now. So I would spend more on panels, not the controller. Another slightly risky thought would be to have two panels with just a on-off switch. 10 extra amps going into the battery anytime the sun shines. It might slightly overcharge your battery if you don't have afternoon loads, the main controller has shut off. But if the battery is not getting full every day, or you have a constant 5 amp average load, you will not have a problem, (with late afternoon overcharging) as long as you shut off the extra panel in summer or while on vacation.

Yes I have a SB 50 MPPT controller in my motorhome 415 watt solar system. That system cost $3000 in the 90's, and could be replaced for about $800 today.

Todd Cory_2's picture
Todd Cory_2 (not verified)

the (now discontinued) mx60 can be set for 70 amps, which means it will process around 72 amps before "de-optimizing" the mppt tracking at this limit. 72 amps X 52 volts = 3.7 kW. mine has processed this amount of power for over 10 years with no problems (on a 24 volt system, this would be 72 X 26 = 1.8 kW).

RMichael Curran's picture

Not to beat a dead horse but the system in the article is 24volts with 2100 watts of PV. Although the MX60 WILL run up to 70A output, seems like frequent operation at the MX60's max rating would shorten its life. Thus my original question.

I guess perhaps the short answer is, if there had been any problems this article would have read differently.

Todd Cory_2's picture
Todd Cory_2 (not verified)

the mx60 will off track the mppt to protect itself. in addition it will shut down if "too hot" (fan failure). outback would not have designed a charge controller designed to fail when operated within the allowable software parameters. these things are very robust!

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