Why Is Conserving Energy Important? Efficiency First Saves Renewable Energy System Costs

A gentleman from Florida, let's call him Bob, contacted us recently with the following scenario:

I am looking for a solar powered energy plug and use system such as the 80 watt solar energy system with a battery and inverter all built into one.

My objective is to find an easy to use system with sufficient power to run a refrigerator for a few hours, and other smaller appliances, fans, etc., as needed. I live in Florida, lots of sunshine but hurricane season is here now and I need an additional power source for emergencies.  Something easy to set up and use, no tools required to install, portable.

I am not adverse to assembling components but it needs to be portable, not designed to be attached to anything.

I replied and asked Bob to give me specifics on what he wanted to operate, all at one time to determine his peak watts requirement, and also how many hours per day for each device.  I also recommended that he look at highly energy efficient alternatives to conventional appliances, etc. before designing a system.

He replied with the following:

Hi Ron,

I looked over what I am trying to power and came up with the following:

Small refrigerator 1.5 amps at 115 volts (1.5 x 115 = 172.5 watts)

Large fans, two of them at .6 amps each at 115 volts (2 x .6 x 115 = 138 watts)

Small fans, two of them at 0.33 amps each at 115 volts (2 x .33 x 115 = 75.9 watts)

Doubt all 4 fans & refrigerator would be running at the same time. With this in mind, I looked at the 80-watt-solar-600-powerpack (and figured I would add an additional Sears battery.)

Every site I reviewed for the Duracell 600 had mixed comments but I found mixed comments on every other battery connected to a solar panel.  Koolatron coolers also have mixed reviews plus do not make ice and do not automatically shut off (no thermostat). I see used small refrigerators for $25-$75 dollars advertised in the paper and Craig's List.

Given my low power requirements, what would you suggest as a configuration?

Low Power Requirements?  Not. 

The first important thing that is helpful to understand is that the average American has no idea how much energy we use every day, and therefore we have no good idea about why conserving energy is important.  A small refrigerator and some fans doesn't seem like much, but when you look at comparing the energy we take for granted in the most energy consuming society per capita in the world, energy generated from highly concentrated nonrenewable sources made from dinosaurs such as coal, or gasoline, or diesel or natural gas or propane versus renewable sources like sun, wind or moving water, the reality of our wasteful energy consumption becomes too obvious.  We are energy hogs compared to the rest of the world.

Here was my reply:

Hello, Bob,

I put my Honeywell 115 VAC 14 inch 3 speed reciprocating fan that we have here in the office on my Kill-A-Watt meter.

The fan uses 48 watts at high speed, 43 at medium speed, 38 at low speed.

I also put I put my dorm sized fridge made in China running on 115 VAC on the same meter and it reads 116-117 watts.

So, figuring that the fridge will run 50% of the time when the air conditioning is off during a hurricane and recovery period, and that two fans will run 12 hours each, the watt-hours per day =

116.5 x 12 =  1398 watt-hours

48 x 12 x 2 = 1152 watt-hours

Total watt-hours 115 VAC = 2,550 watt-hours

AC total connected watts peak = 116.5 + 96 = 212.5 watts

Using this example, a cheap 300-500 watt inverter will handle the load.  You can buy them at Wally World or Tractor Supply or Radio Shack for less than $100.

Looking at the energy requirements for a solar panel system, 2,550 watt-hours / .85 inverter efficiency = 3,000 watts = 250 amp-hours of 12 volt battery per day.  Your 80 watt battery on your proposed energy pack will run for about 30 minutes. Sun Xtender has a 258 amp-hour 12 volt absorbent glass mat fully sealed valve regulated deep draw lead acid battery that is maintenance free and can be safely used in an enclosed room, cost a little over $500 plus freight.

250 amp-hours per day translates into 1435 watts of 12 volt panels, cost roughly $3400.  Plus the supports for the panels, a charge controller, combiner and breaker boxes, cables and wire, etc.  So, you are looking at a system cost of around $5,000.


Investment Versus Expense?

If you bought a SunDanzer solar refrigerator costing $1,000 plus shipping (using 150 watt hours per day) and 2 each NexTek ceiling fans with speed controllers the pair costing $662 plus shipping (using 6 watts per hour per fan) then your watt hour requirements would be:

150 total watt-hours per day for the fridge + 144 watt-hours for the two fans = less than 300 watt-hours per day = 25 amp hours per day = a 104 amp hour AGM battery (which is 4 x oversized in this scenario) costing $258 plus shipping, which you could recharge with one 205 watt panel costing $500, a charge controller costing less than $100, a combiner box costing $150 and you would have power to spare or 3-4 days of autonomy (consecutive days of cloudy weather).

So, about $5000 to run conventional appliances or about $2,200 for a brand new fridge and brand new fans and more than enough energy to run them for 3-4-5 days in a row of cloudy weather.

This is why I said during our first conversation, go for efficiency to conserve energy first, then do your renewable energy system design.


The Energy Conserving Decision?

Bob emailed me back and said thanks, but he had no idea renewable energy was so expensive, so he is going to go purchase a 4000 watt plus gasoline powered generator and a cheap used refrigerator from Craig's List.  This is the typical American way.

During the last good storm we had here in Franklin County, Tennessee, the northwest part of the county where www.nealcreekfarm.com is located was without power most of the evening and night and into the following morning.  When we came into town and into the office the next morning, our next door business neighbor asked me "Hey, Ron, how long was the power off at your house last night?"  I said, Glenn, I did not know the power was off last night, I am off the grid, remember?

I did not have to listen to a noisy stinky generator running all night or go fetch gasoline in the middle of the night.  I could hear the distant departing thunder, and then the toads and crickets and grey tree frogs, a couple of barred owls and Neal Creek splashing down the rocky ledges toward the Elk River as I went to sleep.

I have already made the decision regarding why conserving energy is important and the value of efficiency and investment in my renewable energy system.  Maybe Bob will, too, but it likely won't be this year.

How about you?  Are you ready to start kickin' amps with renewable energy?  Are you ready to begin securing your energy future today?


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