Portable Solar Generator (PSG) Differences

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	GoalZero Yeti1250, $1800	Xantrex/ MSB PowerHub, $3997	JASPak300, $4299	SUNRNR, $4350	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.

3 Small Personal Changes, Immediate Positive Impact on EPA's 30% Carbon Pollution Reduction by 2030 Proposal

photo credit: epa.gov

Whether talking about food, water, electricity, consumer goods, or anything else, it is never a bad idea to understand where things come from, why they cost what they do, their availability, their unintended consequences, and their future impacts.  Americans, for the most part, have been blessed with exceptional access to these and other "commodities", even sometimes taking them for granted or becoming disgruntled if temporarily unavailable. Gratefully, public awareness of these concepts of cause-and-effect, need-or-want, and "what-if?" and the related reasons for making these choices seems to be on the rise.

Examples (and possible motivators):
- concerted efforts to buy locally-grown food (mistreatment of animals, growth hormones, local economy, reduced transportation),
- choosing American-made over price (quality differences, anti-overseas sweatshops, support US manufacturing),
- recycling (awareness of waste, pollution, consumption),
- increased self-reliance, self-responsibility (numerous reasons!)

These choices and changes usually take thought and effort.  Once I decided to stop supporting the use of plastic grocery bags, aka "New Jersey tumbleweeds" (petroleum-product, landfill burden, animal hazard), until it became habit I can't tell you how many times I'd get just inside the grocery store before realizing I had to go back to my car for my reusable bags.  If each of us could change a few tiny things like this ... even just three in the next month, we'd cumulatively make great changes.  And each future change becomes easier.  We make these changes for our own personal beliefs or reasons, but the results can have global ramifications.

It would be great if our utility companies would support us all with the next small change.  If they would give each household a P3 Kill-A-Watt-EZ Energy Usage Meter (or offer at reduced rate), American families could have fun with increasing their knowledge of energy in general and consumption/conservation in particular.  Such a neat little inexpensive device with so much potential impact - see what it takes to make a pot of coffee, how big an inverter is needed to run your microwave, how much stored power your fridge would require during power outage, or how you could do laundry purely by solar.

Let's apply the source/cost awareness above to energy and the EPA's proposed ruling last month seeking a 30% reduction in carbon-dioxide emissions by 2030 from existing power plants based on emission levels from 2005.  Yes, 30% is a large number, possibly inflated to leave room for compromise, but no matter where you stand on global warming, you most likely agree that pollution in any form and consumption of finite resources is not a good thing for mankind.  If we could each cut our electricity consumption by 5-10% through decreased consumption, increased efficiency, usage awareness, or conservation, we would be handing these power plants a 5-10% head-start or more on this requirement.

One place to learn about other easy changes you can make to make a difference is at energy.gov's energysaver website.  Another way, and with immediate impact, is to consider supplemental renewables like portable solar generators.  PSGs come in various sizes, but any comparable to SUNRNR specifications can sustainably provide at least 5% of an average American home's energy usage (given some sun and/or wind:)  They have the added benefit of being available for power outages or for use at non-grid locations.  PSG uses are similar to those of gas generators.  Both provide power independent of the grid, which is beneficial to this power plant proposal, but one still pollutes, robbing Peter to pay Paul using lumps of coal.  And no one in their right mind would want to run a gas generator continuously and sustainably like they could a PSG, to do their part toward requiring less electricity from power plants.

SUNRNR "Spring into Preparedness" Sweepstakes Winners Revealed

Sherry T. of Colorado shows off her prize pack

Winners in a recent sweepstakes sponsored by SUNRNR of Virginia, Inc., a Harrisonburg, Virginia-based solar generator manufacturer were announced just in time to help with preparation for the 2014 Atlantic Hurricane Season. Aimed at raising public awareness about the many ways solar can facilitate improved preparedness and sustainability, entries were accomplished by answering three quizzes of increasing difficulty and covering topics ranging from the impact of power outages to energy storage to what kinds of machinery/devices portable solar can accommodate. The three winners, from Florida, Colorado, and North Carolina, received prize packs that included an energy monitor and emergency supply kit.

"Every item is very thoughtfully included to help my family be prepared for the unexpected," said Sherry T. upon receiving her package. " I plan on carrying it on the back of our ATV when we go into the High Rockies this Summer."

She added, "I want to say "Thank You"  also for the energy usage monitor and LED lights. My Husband and I will use these to better understand and improve on our energy usage."  

“Making sure individual citizens are educated and prepared to respond appropriately to emergencies and natural disasters is critically important to the overall ability of communities to react and recover with less stress and loss of life. The sweepstakes served a dual purpose of raising awareness and assisting three people/families in being ready,” said SUNRNR principal Jenny French.

Joe D. of North Carolina checking out the emergency kit

The promotion was part of SUNRNR’s ongoing commitment to educate consumers about energy issues, consumption and conservation as well as championing the relationship of renewables to preparedness and sustainability. To date, the combined potential power produced by SUNRNR units sold is equivalent to 100,000 gallons of fossil fuel consumed by comparable gas generators – a potential carbon footprint reduction of 900 tons of CO2 from emissions and another 250-ton reduction from non-grid-generated power.

With applications worldwide, SUNRNR is exploring export, particularly to developing countries and at deep discounts in support of relief efforts during catastrophic disasters. International sales of SUNRNR products were the focus of a recent James Madison University capstone project. SUNRNR was also nominated last month for the Shenandoah Valley Technology Council's Center for Innovative Technology Application Award.

More information about SUNRNR can be found at www.sunrnr.com or by contacting Jenny French at jennyf@sunrnr.com, or Scott French at scottf@sunrnr.com, 540.271.3403.

Fun Facts About Solar Energy

Happy Easter, everyone! We hope you are hunting for eggs and having a huge, delicious dinner. We don’t have much time to talk today, but we wanted to share this fun infographic for anyone who is thinking about solar energy. We love infographics – they are a quick and interesting way to scan for information and get the facts. Check it out, and let us know what you think!