Trailer mounted systems?

Re: Trailer mounted systems?

As you have asked the question--You are looking at a 5-10 kWatt genset that will burn a minimum of 0.5 to 1 gallon of fuel per hour.

There are two major design issues with electrical power... The peak wattage which defines the minimum size of the genset, AC inverter, etc. The deep well pump may be a 1-1.5 HP electric motor, and the 4.8 kWatt electric water heater are two killers here.

And then there is the average power per day (Watt*Hours or kWH per day) that you need to supply. That is, more or less, your fuel supply and size of the battery bank (voltage and Amp*Hour capacity). For your cabin, other than the well pump, you do not have much energy needs per day. For your home, the water heater, refrigerator+freezer and such are the primary power usage--But computer systems can also be very significant loads too.

And then there are solar panels... You need a relatively large number of panels to supply relatively large amounts of electrical energy. The sun only supplies power 4-6 hours per day--So you need a large battery bank to charge during the day, and then supply power when the sun is down.

When it comes down to money... Off grid power usually costs in the range of $1 to $2+ per kWH (solar, generator, etc.). That is about 10x the amount you would pay your local utility (in the $0.10 to $0.30 per kWH for most people in the US).

For a generator--Paying 10x the cost for a few days of emergency backup power--Is not going to kill you. However, if you are looking at weeks to months of power usage (major storm damage, off grid home/cabin), the costs to support a "standard North American Home" of ~1,000 kWH per month would be around $10,000 per month power bill.

Generators are (relatively) cheap--So you pay a few thousand dollars for the genset, and pay for fuel as you use it (and if not natural gas, but gasoline/diesel/propane, when you buy fuel for storage). And fuel is the killer (both storage, most fuel goes bad in storage--Propane being the exception, and natural gas from the utility is always "fresh"--assuming you have/keep natural gas during storms).

For solar electric power--You pay a much of the costs for the parts and installation (i.e., pay 5-10 years of electrical bills "up front"), and maintenance--Batteries last 3-5-8 years or so, and electronics last ~10+ years plus the occasional failure. Solar power rarely makes sense as a pure emergency backup power system except for relatively small systems (~1kWH per day or ~100 kWH per month would be my suggested "maximum" backup/part time system design goal for a pure backup system). But that would require you to be "happy" with 1/100'th of the amount of energy you probably use in your home during normal times (no electric hot water, no refrigerator, no freezer, no well pump, etc.).

So--The first step for most of us is to "know your loads", then lots of conservation, and finally, looking at generator+fuel for short term outages (less than ~2 weeks). And possibly at solar+batteries for longer term outages (months) and cabin usage.

Other than a generator+fuel on a trailer--Portable solar is difficult to justify. Batteries are heavy and solar panels are large--Plus you need a good structure for the solar array--You don't want to solar panels to get broken during travel or blown off the trailer during travel/by wind storms.

Comparing a typical north American home of 1,000 kWH per month electrical usage or ~33 kWH per day:

• 0.33 WH per day (330 WH per day) == Lights, cell phone charger, small water pump, a little laptop use
• 1 kWH (1,000 WH) per day == Lights+Radio+LED TV+Laptop+Cell phone charging+small Water pump (assuming you are very careful power power usage)
• 3.3 kWH per day == Add a fulls size energy star refrigerator + well pump (may need new "solar friendly" pump in well) + clothes washer
• 10 kW per day == Add some electrical cooking (microwave, toaster oven, central heat, etc.)--A very efficient home and "near normal" electrical life
• 33 kWH per day == Normal north American home (electric water heater, some A/C)
• 100 kWH per day == Air conditioning for Florida/Texas, irrigation water, etc.

So--Start with your loads and needs... And conservation. Then decide if your emergency power needs are more towards a full time off grid home, or more like short term camping.

-Bill