A Rating System For The Purchase Of A Solar Power System For Your Home Or Place Of Business

How Does The Solar Power System That You're Purchasing Rate ?

Does the solar power system that you're considering for your home or place of business score well on the SPIMNEW^TM test ? If it does not, then you may want to reconsider your purchasing decision.

SPIMNEW^TM is an acronym for an evaluation that was developed for an unbiased method of simplifying the process of choosing the best investment when selecting a grid tie solar power system. Although developed originally for use as a tool in solar power system design optimization, the version included here has
been modified for consumer use.

The acronym may sound a bit silly, but believe me the criteria listed here makes for one very powerful evaluation tool when it comes to making a decision as to which products are best for use in residential and commercial grid tie systems. An easy way to remember the SPIMNEW^TM acronym is to remember the following phrase: "Solar Power, I'm New" as in I'm new at solar power.

SPIMNEW^TM represents the following evaluation criteria :
 

Strength And Size Of The solar panel manufacturer.

PTC Rating of the solar panels.

Inverter Efficiency rating.

Acquisition Cost of the entire system.

Mounting System type and grade.

Negative Tolerance Rating of the solar panels.

Efficiency Rating of the solar panels.

Warranty Duration of the solar panels.

The above criteria was selected because we feel that they have the greatest impact on a customer's return on investment, protection of investment and overall system performance. In general a high SPIMNEW^TM  score has a direct correlation to the overall level of customer satisfaction for the duration of system ownership.

After more than a year of researching the sales techniques that were being used by many in-home solar sales representatives it was determined that almost universally, most sales representatives primarily focus only on one or two of criteria listed above. For example a sales representative might focus on their solar panel's high efficiency but fail to mention the solar panel's poorer negative tolerance rating and higher per watt cost. Or a different sales representative might focus the customer's attention on their product's excellent negative tolerance rating but neglect to mention the solar panel's poor efficiency rating or lesser warranty.

In many post sales interviews, as would be expected, the technique of emphasizing one or two positive aspects and avoiding the many more negative aspects of a products specifications was found to be commonplace. Unfortunately the vast number of consumers simply do not possess the technical knowledge needed to make an informed buying decision and must rely solely on the salesperson's recommendations. This fact is especially detrimental to the consumer when the salesperson's commission is tied directly to the profit margin of the sale.

Using the SPIMNEW^TM criteria when shopping for a solar systems eliminates the guess work and removes the risk of being influenced by a salesperson who is using biased recommendations. The products that are used in any solar power system will either meet these consumer beneficial standards or they will not.

After comparing more that a hundred solar power system quotes, we have determined that purchasing a solar power system with the maximum SPIMNEW^TM score of 90 can save you thousands, even tens of thousands of dollars on your solar system, depending on the size of the system that you purchase. You can also expect that the system that you purchase will provide very high performance and reliability and a very high likelihood that the manufacturer of your system's solar panels will remain in business should you need to file a warranty claim in the distant future. Gathering the information that is necessary for completing the SPIMNEW^TM evaluation and tallying up the score should not take more than 30 minutes of your time and practically all of the answers to the following questions can easily be found on the Internet.

The following defines the selection criteria:

S - What is the STRENGTH and size of the manufacturer of the solar panels in the system that are under consideration ? Pick up any magazine, newspaper, or look on line and you're bound to find some reference to the "Green Revolution". Look a little closer and you'll probably find a wealth of information concerning solar power. Needless to say whenever any new industry gets this much press, it's bound to attract manufacturers and dealers by the boatload.

We've been selling solar power products for over eleven years and the one thing that is for sure is that competition is beneficial for the industry. Competition has brought us a lot of good things like, lower pricing, higher quality products and much more public awareness. On the flip side of the coin though, this awareness has also brought the scam artists, the crooks, the fly-by- nights, the get rich quick schemes and at the very least, hundreds of new companies with good intentions that have little to no previous experience in the solar industry.

Unfortunately its going to take a lot more than good intentions to succeed in this fast growing, extremely competitive multi-billion dollar industry. We've already seen dozens of well established companies simply vanish off of the face of the Earth taking their warranties and replacement products with them. Just in the last year, over one hundred new solar manufacturers have opened in China alone. Many of these companies were manufacturing toys and household goods one day and solar panels the next.

And as the competition strengthens most of these companies too will disappear taking there warranties with them. Don't get us wrong, some of the largest, most reputable solar companies that produce the finest solar panels in the world are located in China. But at the same time there are companies that number in the hundreds from several third world countries that are literally producing garbage that is now hitting U.S. shores. 

This is why we highly recommend that consumers do a little research about the company behind the brand of solar panels that are being offered by any dealer. The simplest method for gathering the following answers is to visit the solar panel manufacturer's website.

1. Does the manufacturer have a name that you readily recognize as a large company with a reasonably long history ?

If the solar panel manufacturer has a name that you readily recognize as a large company with a reasonably long history then give the solar panels a score of 3 points.

If you do not recognize the name, then the solar panel gets 0 points

2. Is the manufacturer a "pure play" company or are they diversified ? In other words does the company only manufacturer solar panels or do they manufacture other non solar related products. ?

If the solar panel manufacturer is a diversified company then give the solar panel a score of 2 points.

If the solar panel manufacturer is a "pure play" company then give the solar panel a score of 1 point.

3. Is the manufacturer publicly traded on a large stock exchange, such as the NYSE ?

If the solar panel manufacturer is a publicly traded company then give the solar panel a score of 5 points.

If the solar panel manufacturer is not a publicly traded company then give the solar panel a score of 2 points.

4. Does the company have more than 500 employees or less than 500 employees ?

If the solar panel manufacturer does have more than 500 employees then give the solar panel a score of 5 points.

If the solar panel manufacturer has 300 to 499 employees then give the solar panel a score of 3 points.

If the solar panel manufacturer has 100 to 299 employees then give the solar panel a score of 2 points.

If the solar panel manufacturer has less than 100 employees then give the solar panel a score of 1 points.

5. Do you feel absolutely confident that if the manufacturer had a catastrophic design flaw that they could survive a recall of the defective products that have been manufactured to date ?

The answer to this question is more a matter of your "gut feeling" about the strength of the company rather than a known fact.

If you feel that the manufacturer is large enough to survive a major product recall then give the solar panel a score of 5 points.

If you feel that the manufacturer is not large enough to survive a major product recall then give the solar panel a score of 0 points.

P - What is the PER WATT PTC rating of the solar panels that are under consideration ? In an effort to create a level playing field, the state of California as well as many other states require that all solar panel manufacturers submit their product's operating specifications. These specifications are compared to real world performance ratings that have been determined by an independent laboratory called PVUsa before they are approved for the state's program. PVUsa uses more stringent conditions than the manufacturer uses and assigns a PTC rating or (PVUSA Test Conditions rating) The difference between PTC and STC is as follows:

1. PTC are 1,000 Watts per square meter solar irradiance, 20 degrees C air temperature, and wind speed of 1 meter per second at 10 meters above ground level.

2. STC are 1,000 Watts per square meter solar irradiance, 25 degrees C cell temperature, air mass equal to 1.5, and ASTM G173-03 standard spectrum.

So a solar panel that has a STC or (Standard Test Conditions rating) of 170 Watts might have a PTC rating of 149 watts. The PTC rating along with the efficiency rating of the inverter is what the state uses to determine the amount of the cash rebate. So the higher the PTC rating that a solar panel has, the higher the cash rebate that goes into your pocket. Needless to say not all solar panels are created equal.

When shopping for a system, you will rarely see two systems that use solar panels with exactly the same wattage ratings. For example, one system might use (20) 175 watt panels and have a total DC Watt rating of 3,500 watts and another system might use 170 watt panels and have total DC watt rating of 3,400 watts. So how do you compare each system's true PTC rated performance and the amount of rebate per watt when two different wattage rated panels are used.

Simply visit the California Energy Commission's website at http://www.gosolarcalifornia.ca.gov/equipment/pvmodule.php and look up each individual panel's PTC rating. For example the 170 Watt panel might have a PTC rating of 152.5 Watts and the 175 Watt panel might have a PTC rating of 154.9 Watts. Simply take the 170 Watt panel's PTC rating of 152.5 and divide it by 170 watts and you'll get a ratio of .897. Next do the same for the 175 Watt panel. 154.9 divided by 175 Watts gives you a ratio of .885. Obviously the higher the number, the higher the per watt PTC rating.

If the solar panel that you're considering has a per watt PTC rating of .900 or higher then give the solar panels a score of 10 points.

If the solar panel offers a per watt PTC rating of .890 to .899, then give the solar panel a score of 8 points.

If the solar panel offers a per watt PTC rating of .880 to .889, then give the solar panel a score of 6 points.

If the solar panel offers a per watt PTC rating of .870 to .879, then give the solar panel a score of 4 points.

If the solar panel offers a per watt PTC rating of .860 to .869, then give the solar panel a score of 2 points.

If the solar panel offers a per watt PTC rating of less than .860, then give the solar panel a score of 0 points.

I - What is the CEC weighted efficiency rating of the INVERTER that is included in the solar power system under consideration ? You can purchase solar panels with the highest per watt PTC rating and literally choke off that performance potential by choosing an inverter with a low CEC weighted efficiency rating. In fact not only can you negatively impact your solar system's performance but can also decrease the amount of your cash rebate by choosing an inverter with a lower efficiency rating. To determine the efficiency rating of the inverter that you're considering for your solar system, simply visit the California Energy Commission's website at http://www.gosolarcalifornia.ca.gov/equipment/inverter.php and look up the inverter's CEC weighted efficiency rating.

If the inverter that you're considering has a CEC efficiency rating of 96% or higher then give the inverter a score of 10 points.

If the inverter has a per watt CEC efficiency rating of 95% to 95.9% then give the inverter a score of 9

If the inverter has a per watt CEC efficiency rating of 94% to 94.9% then give the inverter a score of 7

If the inverter has a per watt CEC efficiency rating of 93% to 93.9% then give the inverter a score of 6

If the inverter has a per watt CEC efficiency rating of 92% to 92.9% then give the inverter a score of 5

If the inverter has a per watt CEC efficiency rating of 91% to 91.9% then give the inverter a score of 2

If the inverter has a per watt CEC efficiency rating of less than 91% then give the inverter a score of 0

Please Note: Battery backed up grid tie inverters inherently offer lower efficiency ratings due to the use of batteries. This selection criteria does not apply to battery based grid intertie systems.

A - What is the ACQUISITION COST of the complete solar system that are under consideration ? Considering how new the grid intertie solar industry is and how rapidly the industry is growing, a universal consumer standard of what constitutes fair or reasonable pricing has not yet been established. As consumers we have a pretty good idea of what constitutes a reasonably priced car and we have pretty much come to know what features should come standard with a reasonably priced car. Automatic transmission, power steering, power brakes, cloth seats, manual windows. We also know what constitutes a luxury car and what we'll have to pay to buy one.

But what about a solar power system for your home ? How do you know when you're paying too much for too little ? How do you determine when you're getting a great deal or whether its time to turn around and run the other way ? Are you aware that if you live on the East cost that for some unknown reason, you'll typically pay a much higher price for a solar system than someone living on the West coast ? Are you also aware that you can pay a much higher price for a solar system by inviting a sales person over to your home versus buying online or by simply visiting a dealer at their showroom ?

Unfortunately in the rush to "Go Green", every few hours, there is a consumer out there that is paying far more than they should be for a poorer performing, poorer quality solar power system. And the sad part is that, it will take years before they realize that they have overpaid for their system. The realization will come in form of the first piece of equipment to fail, or system performance that wasn't quite what the salesperson claimed, or a warranty claim that won't be honored because the manufacturer is no longer in business.

The bottom line is this : You should not be paying more than $7.00 to $8.00 per Watt for any high performance solar system using a high efficiency name brand inverter, high efficiency, low negative tolerance rated, high per watt PTC rated, 25 warranty solar panels installed with heavier duty mounting racks on a typical composition shingle roof and only slightly more for a concrete tile roof. Tilt legs, unusual permitting or engineering costs would be extra. Yet we routinely find consumers that have recently paid $8.50, $10.00 and even $12.00 per watt for product that we would never even consider installing on the roof of our offices.

If the solar power system that you're considering has an installed price per watt of $6.50 per watt or less before sales tax, shipping, rebates and tax credits then pat yourself on the back and give the solar power system that your purchasing a score of 10 points.

If the solar power system that you're purchasing has an installed price per watt of $6.51 to $7.00 per watt before sales tax, shipping, rebates and tax credits then give the solar power system that your purchasing a score of 8 points.

If the solar power system that you're purchasing has an installed price per watt of $7.01 to $7.50 per watt before sales tax, shipping, rebates and tax credits then give the solar power system that your purchasing a score of 7 points.

If the solar power system that you're purchasing has an installed price per watt of $7.51 to $8.00 per watt before sales tax, shipping, rebates and tax credits then give the solar power system that your purchasing a score of 6 points.

If the solar power system that you're purchasing has an installed price per watt of $8.01 to $8.50 per watt before sales tax, shipping, rebates and tax credits then give the solar power system that your purchasing a score of 5 points.

If the solar power system that you're purchasing has an installed price per watt of $8.51 to $9.00 per watt before sales tax, shipping, rebates and tax credits then give the solar power system that your purchasing a score of 3 points.

If the solar power system that you're purchasing has an installed price per watt of $9.01 or higher and you don't have a tile roof . tilt legs, unusual permitting or engineering costs then give the solar power system that you're purchasing a score of 0.

M - What type of  MOUNTING  system is included with the solar power system that is under consideration ? Mounting system can vary significantly from dealer to dealer. There are dealers who will show up at the job site with a chop saw and a load of galvanized steel Unistrut that will make their own "home made" mounting rails, there are dealers who insist on using only heavier duty, factory engineered mounting rails and then there are dealers who will sell only lower cost U shaped mounting rails. Homemade racks typically will not come with any sort of engineering stamps so we recommend that you stay away from this type of product. And the difference in cost between heavier duty mounting rails and the thinner walled U shaped rails is literally only pennies per watt. So needless to say we recommend that you opt for the heavier duty factory engineered mounting rail systems.

If the solar power system that you're considering includes the heavier duty type of mounting system  then give the mounting system a score of 10 points.

If the solar power system that you're considering includes the thinner U shape mounting rail then give the mounting system a score of 5 points.   

N - What is the NEGATIVE tolerance rating or (minimum warranted power) of the solar panels under consideration ? Most consumers are not aware of the fact that they could for instance be paying for 200 Watt solar panels yet the manufacturer will only guaranty that consumer will receive 180 Watt solar panels. The discrepancy is known as "peak tolerance rating", "minimum power max", "minimum warranted power" or "negative tolerance rating". When shopping for solar panels, what you want to look for is the highest minimum warranted power rating, the lowest negative tolerance rating or the lowest peak negative tolerance rating.

A solar panel manufacturer's claim of having a high efficiency rating is worthless if the solar panel has a poor minimum warranted power rating.

What all this means is that the solar panel manufacturer offers a warranty that states that their solar panel's actual power rating will not be less than a certain amount out of the box. So if a 200 Watt solar panel has a negative tolerance rating of 10% then their 200 watt panel is guaranteed not to have a power rating of less than 180 Watts right out of the box. Negative tolerance ratings as low as 2 to 3% are common today. We recommend avoiding products that offer negative tolerance rating that are higher that 3%. Remember this simple rule: The higher the negative tolerance rating, the higher your chances are of receiving products with a lower power rating than what you paid for.

If the solar panel that you're considering has a negative tolerance rating of 3% or lower then give the solar panels a score of 10 points.

If the solar panel has a negative tolerance rating of 4% to 6%, then give the solar panel a score of 6 points.

If the solar panel has a negative tolerance rating of 7% to 12%, then give the solar panel a score of 3 points.

 

E -  What is the EFFICIENCY rating of the solar panels that are under consideration ? Solar panel efficiency ratings are the least important of the solar panel selection criteria but it was included the list in light of all of the new cheaper low efficiency products that are flooding the market. Basically the higher the solar panel's efficiency, the more power the panel will produce per square inch of active cell material. This typically is only a consideration if you have a limited roof area in which to mount your solar panels. Most conventional solar panels that use solar cells that have been cut from solid ingots of silicon offer more than sufficient efficiency to accommodate most roof configurations.

Typically, manufacturers that avoid using solar cells that are cut from a solid ingot of silicon are simply trying to reduce manufacturing cost. This would be beneficial to the consumer if the savings were passed on to the consumer, but in many cases the dealers that offer these lower efficiency solar panels use their lower cost to improve their profit margins instead of offering their customers a lower price. Be especially weary of dealers that make claims of offering the highest efficiency, while failing to mention the remainder the criteria that is mentioned in this article. Remember Efficiency is not a direct measure of a solar panel's performance. A higher efficiency 230 watt solar panel does not generate any more power than a lower efficiency 230 watt solar panel. The only difference is that the higher efficiency solar panel may be slightly small in size. An efficiency rating of at least 13% is recommended but don't go overboard, paying a higher price for a higher efficiency solar panel normally does not make economic sense. As long as the solar panel offers at least 13% efficiency then a much more important specification is the solar panel's price per watt and its negative tolerance rating.   

Smart Tip: Always ask your dealer to provide you with a factory printed specification sheet that lists the solar module efficiency, not individual cell efficiency. If the dealer cannot or will not provide you with a factory printed specification sheet that lists the total module efficiency, then shop elsewhere.

If the solar panel that you're considering has an efficiency rating of 13% or greater then give the solar panels a score of 10 points.

If the solar panel has an efficiency rating of 12.9% to 12%, then give the solar panel a score of 7 points.

If the solar panel has an efficiency rating of 11.9% to 10%, then give the solar panel a score of 5 points.

If the solar panel has an efficiency rating of less than 10%, then give the solar panel a score of 3 points.

 

W - What is the duration of the WARRANTY of the solar panels that are under consideration ? Standard monocrystalline and polycrystalline solar panels both have proven track records with life expectancies that exceed 40 years. Manufacturers of these well established solar technologies are now comfortable offering warranties of at least 25 years. While shopping for solar panels at various dealers, you may come across solar panels with warranties of 20 or even 10 years

You may be thinking 20, 25 years what's the difference ? But what you need to ask yourself is, in such a competitive market, why would a manufacturer offer a 20 year warranty when everyone else is offering a 25 year warranty. When you consider that established technologies should last 40 years, the answer should be pretty obvious.

If the solar panel that you're considering has a manufacturer's warranty of at least 25 years then give the solar panels a score of 10 points.

If the solar panel offers a factory warranty of less than 25 years, then give the solar panel a score of 5 points.

 

Add up the total points and apply the following rating system :

A PERFECT SCORE OF 90: A perfect score of 90 means that there is a very high likelihood that you are investing into a solar system that is using solar panels with the highest performance available on today's market that is from a well established manufacturer that offers the longest warranty currently available. A perfect score of 90 is also an indicator that there is a higher likelihood that the manufacturer of the solar panels will be in existence for the next 25 years to honor their warranty should the need arise. It also indicates that your are receiving one of the highest efficiency inverters that will increase your chances of receiving one of the highest per watt rebates available and have a much better chance of actually receiving the wattage indicated by the solar panel's nameplate rating. This score also means that as of 12-12-2008 you have been quoted one of the lowest prices available on the market. Very few solar power systems will attain this very high score. 
 

A SCORE OF 79 to 89: We consider a score of 79 to 89 to still be a high score. With a high likelihood that you are investing into a solar system that is using solar panels that offers among the highest performance ratings available on today's market, from a well established manufacturer that offers among the longest warranties currently available. A score of 79 to 89 also increases the likelihood that the company will be in existence for the next 20 to 25 years to honor the warranty should the need arise. It also indicates that your are receiving one of the higher efficiency inverters that will increase your chances of receiving one of the higher per watt rebates that is available and have a good chance of actually receiving the wattage indicated by the solar panel's nameplate rating. This score also means that as of 12-12-2008 you have been quoted one of the lower prices that is available on the market. Few solar power systems will attain this high score. 
 

A SCORE OF 69 to 78: We consider a score of 69 to 78 to be average for today's technology and market. It does not mean that you are purchasing a bad product, only that you may want to consider adjusting the price that you pay for such a system accordingly. In our opinion, a system with a score such as this is an indication that your are investing into a solar system that is using solar panels that offer average performance ratings when compared to other solar panels that are available on today's market from a manufacturer that may or may not offer a warranty that is among the longest warranties currently available. A score of 69 to 78 may or may not affect the likelihood that the company will be in existence for the next 20 to 25 years to honor the warranty should the need arise. It also means that you may or may not be receiving the highest per watt rebate and may or may not be receiving the wattage indicated by the solar panel's nameplate rating. This score also means that as of 12-12-2008 you may or may not have been quoted one of the lowest prices available on the market.

A SCORE OF 55 to 68: We consider a score of 55 to 68 to be questionable and would recommend that you carefully consider a score in this range. We would expect that pricing for such a system would be adjusted accordingly.

A SCORE OF LESS THAN 55: With extremely competitive pricing available on systems with a much higher score than this, it is our opinion that you avoid product that fall below a score of 55.
 

You would be amazed at the number of consumers who simply invite a couple of solar salespeople over to their home to provide quotes and sign on the dotted line without ever researching the products that are about to be installed in their home. In fact almost all of the consumers that we spoke with said that they relied entirely on the salesperson's recommendations before making their decision concerning which product was best.

It has been said that most consumers do more research when buying a $500.00 to $1,200.00 T.V. or stereo system that is meant to last 7 to 10 years than when purchasing a $20,000.00 to $50,000.00 solar power system that is meant to last 30 to 40 years.

This is probably due to the misconception that the technology behind a solar power system is simply "too high tech" to fully understand. With the introduction of the SPIMNEW^TM  evaluation tool, any solar power system can now be compared on a level playing field without the influence of a salesperson or the need of an engineering degree.

Copyright 2008 Solar Home, Inc.