Accomplishing an Apple-to-Apple
Comparison in the Apple-to-Orange World of PSGs
When
choosing any piece of equipment, many variables come into play. When that piece of equipment is a generator
or power supply system, the variables may include intended use, size, output
power, noise, energy source, and endurance.
Rather than buying a generator then determining what it will run, defining
the equipment’s application first (its purpose and how you plan to use it) can
be helpful in defining those variables, simplifying the choices, and making the
most of your investment.
|
Wide range of solar products |
- Want
to run air conditioning or a food truck grill?
Better off with grid or fossil fuel as energy source.
- Want
to run an electric water heater or halogen lighting? Try solar thermal or again, gas or grid.
- Is the
goal to run your house? You’ll need a
full residential installation, hopefully with batteries. Check your monthly utility bill - the average
US household consumes over 24kW per day.
- Need
“portable” kW or MW arrays? They make
trailer- and container-sized units.
- Want
to carry it into the woods? Don’t plan
on powering much.
But if
you just want a reasonable amount of power, e.g. to offset grid usage and be
available during power outages, to sustainably run your well pump, or to have
power where there is none, keep reading.
(And by “reasonable”, I mean capable of running home appliances and
tools, even several at once, not just charging a phone or keeping a light on.) Generators in this arena will be compared
below.
If you
are new to or unclear on basic electricity concepts, such as W = V x a, and
their associated numbers, please see the Electricity
Refresher link. An inverter must be
rated for 1800W continuous or greater (120V x 15A = 1800W) to ensure it can
power anything a standard household receptacle could power. A 2013 SolSolutions article, “What
to Look For In Solar Generators”, infers that an inverter with a rating
larger than battery storage capacity is an injustice to the customer. I beg to differ. You do not need to use full inverter output,
dumping the entire battery’s stored energy in less than an hour like you would
by running an air conditioner, but it means the system is capable if
needed. Realistic examples: A well pump
may require 20amps to start, but only 4 amps after and only minutes every hour
– but you can’t run it if you can’t start it.
Two 10amp tools could each run 6 min/hour (e.g. air compressor one
cycle/hour and 600+ cuts by table saw) for a full day’s work at a construction
site. Those tools could not run
simultaneously with a 1500W inverter. The same is true for say a refrigerator,
microwave, fan, and light.
As for
storage, the article accurately states “usable watt-hours” as being 2/3 battery
capacity since battery life is extended by only using the top 50-66%. And if the system is designed correctly,
batteries can easily handle surge loads without degradation. Of course, recharging when possible and at
the correct rate (about 10% total storage per hour) will do the most toward
extending battery life. In the product
examples below, you will notice two models offer solar input of about 5%
battery capacity which means you better not use up what you’ve stored or it
will take forever to recover via solar.
Another offers charging at almost 20% which is not good for an AGM battery.
Other
options, characteristics, specifications, preferences, cautions to consider in
the planning stages:
- What are your portability
requirements or weight limitations? Hand-carried,
wheeled unit, use from pickup truck, semi-permanent location, …? Greater storage = greater weight. (Lithium-Ion is lighter, but 3-4 times the
cost.)
- Do you want energy
generation options other than solar, such as wind, kinetic (bicycle), water,
grid, …?
- If solar, distance desired
between unit and panels (some are combined/inseparable). Cabled panels are often preferred since where
the sun is shining may not be the same place as where power is required. Seems silly to ask, but you would be surprised at the answers … If
planning for solar, do you have good, direct sunshine?
- What is the voltage of the
equipment to be powered? (110V/60Hz, 220V/50Hz, 240V/60Hz, or 12VDC)
- Is 12VDC output also available and
at what amp limit?
- Modified sine wave inverters
are most common, least expensive, and work perfectly for most equipment.
- Preference in country of
manufacture - Chinese or American?
- Electricity should always be
treated with respect. A plug and play
system in a steel enclosure providing no access to the “pointy end” (potentially
dangerous parts like battery, wiring) is safer compared to a kit, a
non-steel/plastic enclosure, or a batteries-sold-separately unit.
- The magic “sustainable”
number (how many Watts you may use daily) is 75% of useable storage, based on reasonable
sunshine daily.
As an engineer, I am reticent to
mix units, but I am going to blend apples and oranges into an oran-apple
smoothie by ADDING an inverter rating factor, sustainable storage capacity, solar
input, bonus points, and even gasoline, all in some semblance of “Watts”, to rate
each standard system vs cost. Think of
it as a point system for specifications and investment. Data is taken from current product websites. And here is a similar, interesting comparison table,
although the data is over a year old.
Please also note, there are dozens of other similar products that could
be in this comparison, but they would likely follow these trends.
Various Portable Generator Models and Basic Specifications
(least to most expensive, left to right)
|
Wagan Power
Cube, $1099
|
MySolar
Backup, $1797
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GoalZero Yeti1250, $1800
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Xantrex/
MSB PowerHub,
$3997
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JASPak300, $4299
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SUNRNR, $4350
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Honda3000, $2330 + 600 gallons gas
= $4580
|
Sol-Solutions
SolMan,
$4995
|
Inverter*,
W cont (surge~2x)
|
1500
|
1800
|
1200
|
1440
|
1100
|
3500
|
2800
|
1500
|
Battery Storage, Whr
|
660
|
720
|
1200
|
2400
|
1800
|
2940
|
**
|
3600
|
Useable Storage = 2/3 total (calculated)
|
440
|
480
|
800
|
1600
|
1200
|
2000
|
**
|
2400
|
Sustainable Storage Available = 3/4
useable (calculated)
|
330
|
360
|
600
|
1200
|
900
|
1500
|
1500**
|
1800
|
Solar Input, W
|
80
|
90
|
60
|
300
|
300
|
280
|
**
|
140
|
Bonus Points:
High-load inverter?
Other than solar?
Expandable
system?
Pure sine or 240V option?
Made in USA?
|
--
--
--
--
--
|
--
--
--
--
200
|
--
--
--
200
--
|
--
--
--
--
--
|
--
--
200
200
200
|
200*
200
200
200
200
|
200*
<-200>
--
--
--
|
--
--
--
200
200
|
Total “Watts”
|
410
|
650
|
860
|
1500
|
1800
|
2780
|
1500**
|
2340
|
Total “Watts” divided by Cost
|
0.37
|
0.36
|
0.48
|
0.38
|
0.42
|
0.64
|
0.33**
|
0.47
|
Grey = not included in total
Green = higher total “Watts”-to-cost ratio; best value
proposition, at least if the specifications meet your bottom line needs in
the first place. (A 1200W inverter
most likely cannot power an 1100W microwave, much less run anything else at
the same time.)
Yellow = see * and ** notes to right
Red = not so much.
|
* I would like to have used these inverter
output numbers since one stands out, but in the spirit of apples and oranges,
I decided to deny full credit inverter capability points and just give bonus
points for being able to run two 10-amp appliances/tools simultaneously
(inverter >2400W).
** A comparable gas generator was included for
fair comparison to Traditional Territory. With no gas, thus no power output, its
Total Watts/Cost is 0. Let’s call the
following a cran-apple comparison to allow the Honda to compete. Six hundred gallons of gas at $3.75/gal
makes its cost roughly equal to the three highest-price models and able to
output 1500W daily for almost five years.
|
One
spec that stands out in the table above is that the gas generator is the only
comparable system to even approach SUNRNR’s inverter output capability. There is a reason for that … it is tricky to
ask a lead acid AGM battery to give up that amount of power, at
least safely. SUNRNR solved that issue
in its proprietary design and its proven and patented system. Also note the bonus points for accepting
alternative renewable energy sources such as a wind turbine. (The Honda lost points for being
carbon-based.)
Here is the comparison in a visual format:
Knowing
your requirements and expectations is the key to investing in the right portable
solar generator for your home or business. Once you have identified your
applications, take the time to compare product specifications and value to help
you choose the most appropriate PSG for your needs.
Comments
welcome. Also, I’d be very interested in
seeing a Consumer Reports analysis of PSG products. Please let
them know if you are interested, too.