"Why does one contractor quote prices in DC watts and you quote prices in AC watts? I'm a bit confused".

The industry uses the standard of CEC AC watts when referring to a photovoltaic system's size. There are times when a contractor quotes prices in DC watts. This can cause confusion with homeowners. It's important to know the difference. Click here to read Understanding of STC, PTC, and CEC AC watts.

“When a solar power system is installed, you guys pull a permit. Doesn’t the county re-assess the value of my property and what does this do to my property taxes?”

Indeed, the property of you home increases when you install a solar power system. But to foster solar in our state, our legislature has passed laws that disallow a property tax increase due to a solar installation. In fact, solar is the only home improvement project that will not raise your property tax. Solar owners will, however, receive a form to fill out from the assessor’s office only for information purposes. Here’s an example from the county of Fresno.

“I’ve heard PGE will be coming out with new meters. What does this mean to me?”

PGE has been granted permission from the PUC to proceed with their “Smart Meter” program. This ambitious project will replace 9.3 million meters statewide by 2011. If you have a new solar system installed, a new Smart Meter will be installed. The nice thing about these is they can be read remotely meaning no more utility readers. Also, they will allow for a broader choice of energy price choices. Read more here…

"Solar is too expensive. I can buy a lot of electricity for the cost of a solar system"

Many people dismiss solar energy because of the perceived high cost involved. It's true one can purchase a lot of electricity for the cost of a system. But in the end, they have nothing. Customers who own their own power systems, however, usually pay the same amount for electricity as they always have but a portion goes to paying down their system, which will eventually be paid for. The person without solar will continue to have rate increases and essentially be "renting" their electricity. The analogy of buying a home versus renting a home applies to solar. Example: Joe and Sam have the same $300 electricity bill. Sam says solar is too expensive. Joe decided it made sense and sees his bill drop to $150 and his payment for the solar system is $110 immediately netting him $40 per month. After 7 years Joe's system is paid for with only with what he wasn't paying PGE. Joe's bill is now half of Sam's for decades to come. Sam finally gets a solar system and says, like all of our customers, "I should have done this years ago".

"I have been thinking about solar for a long time. It's a good idea but I'm waiting for prices to come down and rebates to go up. When do you expect solar prices to start to fall?

If someone tells us that “there has never been a better time to buy”, we usually dismiss it as marketing hype. But unlike a vacuum cleaner or a water softener, “…best time to buy” is a fact when it comes to solar power. The rebate levels have, and will, continue to decline and prices have, and will, continue to rise.

A study by Environment California concluded that, since 2001, solar has increased by an astonishing 5,900%. Indeed, the solar revolution is here. Cost factors, like any other sector, are determined by supply and demand and right now, the demand is high. German, Japanese, Chinese, and new American module manufactures are ramping up production to meet the demand. Logically, the prices should come down. But a recent study by PHOTON consulting paints a different picture as the unexpected worldwide demand for solar expands pushing pushing prices upward. Read more here…

" My friend told me that PGE will pay me for the excess electricity I generate from my solar power system".

We've heard commercials telling people that the utility will buy back electricity from customers who have solar energy systems. This is a half truth. The utility is required to give credit for excess electricity sent to the grid from a solar power system. If a customer does not use their credit in one year's time, he or she will lose it and essentially donate it to the utility. This is why it's so important to understand sizing your system.

" I have a 2,000 square foot home. What size system do I need?"

Estimating the size of an Unlimited Energy Solar Power System depends on many factors. Two identical homes can have very different electrical usages.  For example, a home with a working couple and no children will likely use less electricity than the same 2,000 square foot home with 2 young children and a stay-at-home mom. Or, one homeowner may place high value on comfort while their neighbor (with the same size home) may be conscious about the cost of their utility bill. In order for us, or any legitimate solar contractor, to determine a properly sized system, we will need your annual kilowatt hours used. This way, we can analyze your usage and suggest a system based on your usage and personal goals with solar power.

" I've heard there are new rebates and Tax Credits available. What are they?"

The California Energy Commission currently offers a cash rebate of $2.60 per watt for solar electric systems to most of California's ratepayers.  This rebate is scheduled to be reduced 20 cents per watt every six months. " Now is the best time to buy" is an old, tired marketing term. But in this case, it's true. Residential customers currently qualify for a 30% Federal tax credit (capped at $2,000) in the tax year the system is installed or paid for.  Commercial customers qualify for a generous, uncapped, 30% Federal tax credit plus accelerated state and Federal depreciation. A customer who has a home based business may be eligible for both the standard $2,000 Federal Tax Credit and a portion of the 30% Federal Tax Credit for businesses.  Always consult your CPA for your actual tax benefits.

The landscape of renewable energy in California is constantly evolving. It is likely that California will replace the current "up-front" rebate with a Performance Based Incentive (PBI). What this means is that customers will pay the full amount for a solar power system and, as their rebate, receive payments over a 5-year period. Read more about the PBI here...

"I understand there is new solar technology on the market. I want the best solar system and I don't want something that will be outdated in a short time. Should I wait?"

There will always be new technology on the horizon. But the current silicon based photovoltaic technology has the very important distinction of being time tested (decades, in fact) and is highly cost effective.  Other solar technology has not met our standards for reliability, production, and cost effectiveness.

" I want the solar tiles that are a part of the roofing material. How much do they cost?"

The total cost of a solar system using solar tiles is approximately 30% more than traditional silicon based solar modules. Solar tiles require much more labor, are less efficient, and carry a warranty that is 40% shorter than traditional solar modules. Although Unlimited Energy has installed these systems, they are cost prohibitive for almost all homeowners and less attractive financially to most businesses.

" There are a lot of solar companies around. Why should I choose Unlimited Energy?"

Customer care, integrity, expertise, experience, reliability and longevity are just a few reasons why Unlimited Energy is the best choice amongst our competitors.  Our installers are individually trained to the highest standards of workmanship. Our Installation Director, Dennis Cox, has developed an "in-house" apprenticeship program that ensures the quality we're known for. Our expertise has been recognized by the City of Fresno, the State of California, and homeowners and businesses throughout Central California. We've been in business in Fresno since 1984 and we are the only solar contractor in the area that is a member of the Better Business Bureau in both Fresno and Bakersfield. Our aggressive pricing is the result of our tremendous volume allowing us to negotiate the best prices direct from manufacturers. We warrant what we sell so we choose the highest quality components that are field tested in our Central Valley. Our racking system, superior in every way to the industry standard, is manufactured locally thus cutting costs further. In short, Unlimited Energy offers the best installation, and the best warranties, all at the lowest cost. It's that simple.

May 2005

This guide uses California Energy Commission standards for photovoltaic systems. The rebate calculation, performance ratings, and calculations are all California specific. Those of you who are in other parts of the country may have other incentives and standards.

It seems there's a bit of confusion about how to properly name the size of a system in terms of watts. There is talk of standardizing sizing in the industry to end the confusion. But for now, STC,PTC,CEC,and DC watts can be confusing. The differences are substantial in terms of what you pay per watt, comparing the prices from different dealers, and what the rebate amounts are. Also, it’s important to compare “apples to apples” when shopping for a PV system. California is # 3 in the world for photovoltaics and they’ve developed a widely respected standard that we’ll explain here.

Detangling the watt question

There are a few terms that need to be understood about solar electric systems:

STC DC watts-The nameplate rating of a solar module.

PTC DC watts-the rating of a module in real-world conditions as determined by the California Energy Commission.

CEC AC watts-the total PTC DC of solar modules factoring in inverter efficiency. This the number that the rebate is based on.

When a solar modules nameplate says 175 watts, this means that in perfect conditions the module will produce 175 watts of power. In controlled conditions a manufacturer will use something akin to a camera's flash to measure how much power comes out of the module. This measurement is called Standard Test Conditions or STC for short thus the nameplate rating is known as STC watts.

In order to determine truly what a solar module is capabale of in the real world, the state of California requires that all solar panels be tested by an independent laboratory called PVUSA before they are approved for the state's program. PVUSA tests every solar panel using more stringent conditions than the manufacturer uses and assigns a PTC rating to account for dust, wiring losses, module mismatch, weather, etc. They publish their findings on their website:

http://www.consumerenergycenter.org/cgi-bin/eligible_pvmodules.cgi

For example, a 205 watt Sharp ND-205U1 module is rated at 180.6 watts. This revised wattage is referred to as PTC watts, or Performance Test Conditions watts.

Because the CEC rebate is predicated upon final AC watts, and because these AC watts ultimately determine how much useable electricity comes out of the system, it’s important to understand them. So far, we’ve learned that PTC watts are the performance, or real-world, rating of the module and that STC watts are in a perfect world.

All of the power generated from the solar modules is converted from Direct Current to Alternating Current (DC to AC). This conversion is performed by the inverter which has its own efficiency rating. Like solar modules, the CEC has inverter efficiency ratings they use:

http://www.consumerenergycenter.org/cgi-bin/eligible_inverters.cgi

Let’s use an example of 18 Shell 175 watt modules and one PV Powered 2800-XV inverter to do some calculations.

The 175 watt modules are rated at 158.3 watts (PTC). 18 modules multiplied by 158.3 equals 2849 watts. The PV Powered 2800-XV inverter has an efficiency rating of 94.5% thus the AC size of this system would be 2692 (2,849 multiplied by .945)

This chart may help explain…

Example: 18 Shell 175 watt PC175 and PV Powered 2800-XV inverter

Module wattage = 175

CEC rating = 158.3

# of modules = 18

18 x 158.3 =2849

Inverter efficiency = 94.5%

2849 x .945 = 2693

2693 x $2.60 per watt rebate =$7,001

That’s all there is to it. Once you know STC, PTC, and CEC AC, solar becomes much less mysterious and you’ll have a lot more confidence when shopping for a PV system.