Do you have any experience with propane refrigerators? If so, what model small refrigerator do you recommend for a small cabin that will be used year-round?
Thanks so much,
Tex
Tex,
We have included propane refrigerators and freezers on many solar off-grid homes, but since most are based on heating a gas to cause the cooling cycle, I would not use them in an application where the home is not occupied for many parts of the year like a typical weekend cabin. After the first few years there are some maintenance issues that you need to take care of to keep them operating properly, and they do use a lot of propane.
We have switched to the 12/24 VDC small 50 liter refrigerator or the larger 8 cu.ft. top load freezer by SunDanzer that operate from solar charged battery. They require very little solar power to operate due to their very heavy wall insulation, and do not use a flame like the propane units. I think if properly installed they are a much safer and offer a longer life solution, although they are more expensive.
Good luck,
Jeff Yago
Jeff,
Thank you for your quick reply
If you do not mind another question, I am wondering what brand of 50 liter refrigerator would you recommend? And, pardon my ignorance, but what does the “V” in VDC mean? Does it mean voltage?
You can see I am at the beginning of the learning curve relative to using solar energy/alternative energy sources to achieve energy independence for a small cabin.
Thanks,
Tex
Tex,
SunFrost and SunDanzer both make really great super-efficient DC refrigerators and freezers. All SunFrost models are stand-up designs, and all SunDanzer models are top load. You may like the stand up version better, but they are pricey.
I have worked with both for almost 15 years and each has their advantages. Up until this year, the SunDanzer units were in the 8 cu.ft. range which is fairly large. This spring they came out with a 50 liter unit which I found to be perfect for a week-end cabin type application due to the small size and very small battery usage. However, it’s a top load and must be ordered either as a freezer or a refrigerator, but not both.
When we say “VDC” we mean “volts DC”.
Click Here for ome other useful solar terms
Hope that helps.
I have a situation not completely unlike Blake McKinney’s cabin (issue 83) in that I am planning an off grid cabin that will only be used once in awhile — in northern Wisconsin! Was considering solar hot water (closed glycol system) that might be able to be integrated into a radiant infloor (also with glycol) system to keep the house/plumbing from freezing when no one there. Do you think this is reasonable? Electric to run the pump would be from PV modules/battery bank. Would you still recommend a propane wall heater as backup?
We would use a high efficiency wood stove to heat home when occupied.
Our solar exposure is considerably better than the McKinney place.
Also, do you know of any remote monitoring system for house temperature, etc that could use cell phone signal to communicate info back to us at our main residence 90 miles away? :)
Finally, is it generally recommended to NOT let your propane generator automatically switch on to recharge the batteries when no one is around?
Thanks a bunch,
Mark
Mark,
That’s a lot of questions!
I would not recommend trying to heat a home with an active solar system for long periods of the winter when nobody is home. There are too many little things that can turn into big things when nobody is there to correct. For example, a big snow can cover the solar array for days if nobody is there to clear them off. A pump could fail, or the system could leak. Even a small leak of a sealed antifreeze system will cause makeup water to enter and could cause the now antifreeze in the loop to freeze.
I would deal with this in one of two ways. Either design a passive solar home that has enough thermal mass to keep from freezing at night, or design all the plumbing to slope to 2 or 3 low points where you can completely drain all the piping before you leave. Blankets and sheets on beds and clothing in closets will become “musty” under these conditions so I would strip the beds and remove anything that could be damaged from the cold and/or dampness.
I would not leave a generator on automatic start if I was going to be gone longer than a weekend as a simple control glitch or battery problem could cause the generator to run until it ran the tank dry.
There are now all kinds of remote Internet and wireless phone based controls to allow monitoring of remote homes and businesses. We have inverters that will send an email to the installer if there is a problem, and there are Internet based cameras that will send you live video of inside your home if the alarm is activated or there is a water leak.
I suggest that you keep it simple. If the pipes are dry and you remove anything that can be damaged from the cold, why spend all that money to heat someplace you will not be for months at a time.
I’m considering buying a backup generator. I have street LNG to the house. I assume since it always has pressure, as long as suppliers don’t shut it off, I’d be ok. But if there were a period of extreme social disruption, suppliers may do just that, in which case the unit would be useless. I could go with a liquid fuel unit, but don’t really want to store fuel. What’s your opinion on the disruption problem? The 1st on-line sizing calculator I found says I need a 17.5 kW generator.
Thanks,
Rob Wagner
Rob:
I was a boy-scout, so I always believe in their motto – “Be prepared”. Having said that, I do not know how big your house is, but a 17.5 kW generator is REALLY big for a home, unless it is all electric with 2 or more heat pumps. We have found a generator in the 8 kW range will handle everything in a typical home except air conditioning or electric heating. This size unit will easily power all lights, kitchen appliances, big screen TV and audio equipment, freezer, micro-wave oven, and well pump. It will also power your furnace fan if you have gas heat, but will be on the edge if you also try to power a heat pump or AC unit. Going up to a 12 kW generator will usually power all of the above, plus one fair sized heat pump or air conditioner.
I have many clients with homes having 4 or more heat pumps or AC units due to the large size of their home. I always tell them to decide what parts of the house they really need during an extended emergency and only heat or cool those spaces. This will not only reduce the size generator needed, but also the fuel since most generators use almost the same fuel at half loaded as full, so a over-sized generator only lightly loaded will usually use more fuel than a generator sized better to match the load.
As far as emergencies go, usually natural gas from the local utility is more reliable and available during storm related power outages, but there are times during line breaks or peak loads in the winter when line pressures drop. Any generator designed for natural gas can be easily converted over to run on propane. The Kohler line which I favor has a manifold block that has 2 pipe plugs, which are moved from one port to another to change over from propane to natural gas. It would be fairly easy to make a piping arrangement to allow a quick disconnect from the city line to a line from a underground propane tank, but I would make sure you are using a piping connection that must be first disconnected from one supply before connecting to the other or you could have a very dangerous situation if high pressure propane gas passed into the lower pressure city gas line.
If this is a real concern why not just keep the generator connected to a underground 500 or 1000 gal propane tank? Propane fuel does not go stale like gasoline, and you generator will always be ready as long as you run it every few weeks to keep it lubricated and battery charged.
I have a fireplace in my basement and wood like to augment my propane/hydronic heating system with a wood stove fireplace insert similar to your setup. My question is about the water jacket that you use. Is it off the shelf product? Custom? Can you provide insight into the set-up that you did not detail. Your expertise would be appreciated!
Thom Pecoraro
Stephentown, NY
Thom:
This is another great example of class action lawsuits forcing great products off the market.
Throughout the 1970’s energy crisis there were several nationally sold fireplace inserts and fireplace grates that heated water. This made it easy to pipe all the wood heat to hydronic baseboard heaters in other parts of the house, or to a hot water coil in the ductwork and heat the return air being ducted to the other rooms without operating the electric strip heaters or gas burners. I purchased several of these “Hydro-Heaters” for other projects, including the one I now have in our solar home. I had it the new unit boxed up and put in storage for almost 15 years, then installed it in 1992, and it has worked perfectly for the past 16 years.
There also was a firm in northern California I visited in the late 1990’s that was making a great wood-fired hot water heater for remote home-sites. It looked like a standard gas hot water heater, but the bottom half was a fire-box and the flue went up the center. You built a small wood fire and waited about 30 minutes, then you had enough hot water for several showers and dish-washing. They made a “tank-less” version that was just a fire-box surrounded by a water jacket, and you pumped the heated water to a larger storage tank or hot tub. I also purchased one of each and am still keeping them for future since this firm is now out of business and to my knowledge was the last company still making these in the US.
What happened was most state and federal agencies viewed these products the same as a steam boiler since they can explode if not properly installed. For example, all of the models that were sold in the 1970’s always came with a temperature relief valve and a pressure relief valve. If you have a large fire going and the water pump stopped pumping when the power went out, without any water flow the water jacket would quickly turn all water still left in the heater to steam. I have witnessed several times when this happened and all the only thing you saw was some some steam safely venting to a floor drain or outside. However, if the relief valves were not properly installed, the pressure could reach a level that would rupture the steel jacket or under extreme cases even explode. There were not only cases of tank ruptures due to missing relief valves, but even a few cases where a relief valve was piped to the outside and a small drip through the valve due to a weak spring would run down the pipe and freeze during winter weather. After several days the relief valve’s discharge pipe would totally plug up with ice, then if the pressure increased due to a power outage stopping the pump there was no place for the pressure to vent.
I know that there are millions of these wood fired hot water heaters and hydronic fireplace grates being sold in third world countries every year, and I think the California manufacturer moved his operation to Mexico years ago, but I am not aware of anyone making a hydronic fireplace insert that is legal today. If any reader out there can provide this information we all would be grateful, but I think the cost to get these UL listed and the cost for liability insurance for any manufacturer makes this impossible today.
If you really want to heat your home with wood using a hydronic system, I suggest installing one of the many outdoor packaged units you see advertised in Backwoods Home, and in an article I provided on this subject. Since these outdoor units use a non-pressurized water jacket system to pipe hot water to heat the home, they are safe and easy to install.
My weekend cottage is powerless at moment, but running the lines to attach it to ‘the grid’ is estimated to cost $16,000 ! I am approx. 300 yards away from nearest power box. So instead of doing grid tie solar, I am now contemplating off grid solar and looking at generators for backup.
Sounds like diesel is the way to go for reliability and low maintenance, which is my biggest goal. I am willing to pay a little more for this.
My question is, what do you think of running Biodiesel in most modern diesel generators? Is this feasible? Is this for summer time only? (I live in northern Wisconsin, and wonder if Biodiesel mixes would freeze!).
I’m trying to be as ‘earth friendly’ as possible.
Thanks!
Mark
Mark:
Being totally off-grid is not as easy as you think unless you have lots of solar modules and batteries, and really limit the use or quantity of larger appliances. Having said that, depending on your solar exposure and location, the more solar you have the less generator run time so fuel type may not be a big issue.
Some diesel engine manufacturers will void their warranty if you use bio-diesel, although this is changing as manufacturers get more experience with bio and the quality of the fuel processing improves. However, not only bio-diesel, but regular diesel fuels can be a real problem during the winter unless you use crank case heaters, fuel pre-heaters, and other heating devices to prevent the fuel from turning into gel. If you think solar is expensive just to run a few appliances and lights in an off-grid home, wait and see what it will cost you in batteries and solar modules just to power a crank case heater on a diesel generator all winter !
This is why many backup generators are propane. The fuel does not go stale, it does not freeze, and you don’t have to worry about it turning into a semi-solid in the fuel lines. A fill up once a year to a 500 gallon underground tank should not only give you many months of backup power, but can also be used in a gas stove since you will not be able to have an electric stove in an off-grid home.
We own a home which is “off grid”. Rather than use a wood burning stove, I want to install propane and get a propane range. Problem is, we don’t want the pilot light burning all the time, and the existing spark igniters are all electric! The easy solution is to light a match every time I want to light a burner, but I’m wondering if there isn’t a way to modify (or build) a non-electric spark igniter that sparks when I turn the burner on (or that is powered by a couple of AA batteries). Got any ideas?
Jessica Laube
Jessica:
The answer depends on the brand and model of your stove. Most very basic stoves with no electronic displays or timers, will have a spark ignition system that uses little or no electricity except for the brief period the valve triggers the spark. However, we designed an off-grid solar-powered home several years ago that based on our calculations would only need the generator to run about 3 hours once a week. After completion, the generator had to run several hours every day to avoid a drained battery each night. We said this was not possible, and returned to the site with full metering equipment.
After checking every circuit, we discovered their General Electric propane gas stove used more electricity than the entire house! Since GE loves electricity, they designed their gas stove with a “glow plate” down next to the oven burner which glows cherry red the ENTIRE time the oven is operating! Needless to say, we sent this stove back and had the homeowner purchase a non-electric model.
I would not try and modify your gas stove. Check to see how much electric ignition and controls draw when off, and then when energizing the spark ignition. If this is too much, then dis-connect and light with a match. This way there is no pilot light wasting gas.
I recently stumbled onto your website. It is very helpful! You have great articles, and therefore, seemed like a person I could send my energy “situation” to for advice. Here it is:
My wife and I live in a large (4500 sq ft), 3-story house in northern Maryland. Our two energy sources are electricity and propane gas for heating. The main shape of the house is square. But from that body it has two “wings”. The first wing is a 2-car garage, with a room above it. The other wing is a large bathroom and walk-in closet.
In the summer the trees that surround the house aid in keeping the entire house relatively cool in the summer. I recently added ceiling fans to the first floor (study and living room), the second floor (3 bedrooms and a movie room) and the third level (the roof was designed with trusses, allowing an arts and craft room). The fans keep the air flowing –and the house cool enough–where air conditioning is not necessary except for days where it is 100š or higher.
The problem is heating the house in the colder months (primarily late November through early March). I have a 1000 gallon propane tank and can go through 250 -300 gallons of propane a month during this time. At roughly $2 a gallon, this amounts to $500 – $600 a month.
Beyond the wings of the house, which are very cold in the winter, the other challenge is that the central part of the house (the 20′ x 20′ living room) has 20′ cathedral ceilings. To cut our heating costs, my wife and I are considering a wood stove for this room, We are also considering buying a tankless instant propane hot water heater.
I’m looking into solar hot water system, but it doesn’t appear to be a viable option, especially given the cost to install it, and the low return on heated water in the winter when we would really need it.
Any further suggestions on cutting down on my heating bills?
Thank you in advance.
Stephan
Phoenix, MD
Stephan:
You have a very large home and it costs more money heat and cool than a small home, no matter what you do. Your cooling costs are low because the high ceilings allow space for the hotter air to rise, and most likely lots of cracks around windows or open windows to provide good ventilation. I have visited many very high end large homes that the owners just could not afford to heat. Most put up barriers and sealed off all but the main rooms they lived in during the winter. They even had plastic sheeting at all doorways inside you had to push aside to go from one room to another. I could not live like this and feel very strongly that if you cannot afford to heat the home you have, maybe its time to move.
It sounds like you need to either get a wood stove for your large living room, or maybe one of those outside wood boilers that can heat your entire house, assuming you are able to keep it loaded with wood all winter. Just for the record, solar is out of the question for your situation due to the very high cost and high energy demand.
I am currently building a house, and read your article on generators used with a battery/inverter system to provide off grid power. This intrigued me.
My question is whether or not it is better to get an LP powered generator, versus a diesel because of the price of fuel. The price difference in my area is almost $2.00 per G. I realize that diesel motors usually have greater longevity than other types, but Guardian has introduced an 1800 rpm liquid cooled 18KW generator, and I’m wondering if that might not be more cost effective.
I would also appreciate any info you could provide that would allow my builder to do the install correctly for a future battery /inverter system.
Thank you.
Sincerely,
Mike Jamison
Mike:
My selection of generator type has to do with how often it will be running each week, month, or year. For example, if I want a generator for backup power for a home on the grid that only suffers a power outage for a few hours or days each year, I would select a propane generator as the fuel (propane) does not go stale or get old, so it can sit in the tank for years until needed. Of course you should run the generator every few weeks to keep everything lubricated and operational.
If I was designing an off-grid solar home and the solar system was large enough that the generator would only be needed to run a few hours each week, I would also select the propane fueled generator for the same reason.
If I was designing an off-grid system that needed a generator to run many hours each week I would select the diesel generator as the fuel costs will be lower and would also allow making my own bio-diesel if needed. Since this generator would go through a fuel tank much faster than an occasional use generator, there is less chance that the diesel fuel would go old. Of course you can add additives to the diesel to make it store better, but most of these additives are expensive and another thing to take care of.
If the home’s location is not accessible for filling the propane tank with a propane delivery service truck, you may have to select the diesel, as it will be easier to deliver the diesel fuel in 5 gallon hand-carried fuel cans.
As you see, all designs are have trade-offs and there is not always a perfect answer.
