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Posts from January 2010

Solar Data Monitoring in California

The California Solar Initiative (CSI) is an organization that offers a cash back incentive for putting a solar system on your home or business in California.  There are two different rebate programs, Expected Performance Based Buydown (EPBB), and Performance Based Incentive (PBI). The rebate values vary according to system size, customer class, and performance and installation factors, as shown on the chart below:

CSI Rebate Graph

Here is the EPBB rebate explained by the CSI website:

Owners of solar systems less than 50 kilowatt (kW*) may apply for an up-front cash rebate known as the Expected Performance Based Buydown (EPBB)**. Program Administrators calculate a customer’s rebate using the expected performance of the owner’s system based on equipment ratings and installation factors such as geographic location, tilt, orientation and shading. Customers receive their incentive payment in a lump sum after their system in fully installed and interconnected.

And here is the PBI:

Customers with solar systems between 50 kW* and 1 MW must* apply for the Performance Based Incentive (PBI) structure. PBI incentives are a five-year stream of fixed monthly payments determined by the actual output of the system, as metered and reported to the utility. After January 1, 2010, all systems greater than 30 kW must choose the Performance Based Incentive structure. The PBI incentive path is available at any time to ANY size system.

The table below shows the effect of prices as these step declines occur, with current prices in the three territories highlighted in yellow. Residential and commercial incentives are the same price in each step; however, local governments and other tax-exempt organizations receive a slightly higher incentive because cannot qualify for Federal Investment Tax Credits on their solar systems.

The table below shows the rebate levels available at various steps, and information on currently applicable step in your region is available at the California Solar Initiative Trigger Tracker.

However, there is a catch. In order to use this great incentive, the homeowner or business must “record the output of the PV generator”, and “pay for 5 years of data communication and performance monitoring and reporting services” (emphasis mine). So who are these Performance Monitoring and Reporting Services? After some major digging through the beaurocratic labyrinth of CSI and Pacific Gas and Electric’s websites, I found this list:

  1. Applied Power Technologies, Inc.
  2. Deck Monitoring, LLC
  3. Draker Laboratories, Inc.
  4. Energy Recommerce, Inc.
  5. Enflex
  6. Enphase Energy
  7. Fat Spaniel Technologies
  8. Locus Energy
  9. NergyOS, Inc.
  10. Recurrent Energy
  11. SatCon Power Systems
  12. SolarCity
  13. Thompson Technologies, Inc.
  14. Trimark Associates, Inc.

So there you are! The list of the 14 privileged Performance Monitoring and Reporting Service providers. These chosen few capitalize on every solar installation in the state of California.

Solar PV installations: Beyond “measure twice, cut once” – Photovoltaics World

by John Williams, Solar Panels Plus

December 18, 2009 – A successful solar photovoltaic installation is one in which the customer is happy and has received what was expected. Some would say that a proper installation is the first step. While a proper installation is of crucial importance, the most important first steps usually occur during the selling process where information is gathered, a proposal is generated and where the customer expectations are set.

In order to properly set and manage customer’s expectations, a certain amount of customer education is required. Many times a solar salesperson will avoid some of the technical detail if he or she believes the customer may not be interested or not be technically astute enough to understand. Also, some salespeople may often omit what they consider borderline requirements or specify less capable equipment in order to have the lowest bid and win the sale. In situations where any of the above occurs, the likelihood of an unhappy customer situation is increased. It is far better to cover everything up-front and risk losing the sale, than it is to make the sale and later have to apologize and explain important information after the fact.

A good first step is to explain to the customer how solar panels are rated and how efficiency is related to the larger picture. Once a customer (and the salesperson!) understands this basic information, most of the additional information that we will recommend sharing will be more easily understood.

Rating

Solar PV panels are rated in Watts-peak. This means for example, a solar panel rated as “200W” really means that (±3-5%) this is the maximum or peak instantaneous wattage that can be produced under STC (standard test conditions). STC assumes several important factors that are not always present at a specific customer location. STC is stated to be a condition where the panel temperature is 25°C (77°F) and where the panel is perpendicular to the sun, and where the sunlight conditions produce 1000W/m2 of insolation (direct sunlight). A 200W panel will not produce 200Wh (watt-hours) each hour all day long, rather, it will produce up to 200Wh per each hour of full strength insolation. In many parts of the US, the adjusted hours of insolation will be between 5-6 hours per day in the summer, and 3-4 hours per day in the winter. The table at right provides a snapshot of insolation values for a few major US cities.

Efficiency

The efficiency of a PV panel is often misunderstood and misused in the sales process. A “high efficiency” panel is usually not the best value for the customer. Efficiency of a typical poly- or multicrystalline silicon PV panel may be in the range of 14%-16%. Efficiency of a more expensive monocrystalline panel will usually be in the range of 15%-18%. Some very expensive panels are reaching the 22% range. At a practical level, efficiency only affects (in a relatively small way) the amount of roof-space that a panel will need. For example, 200W panel at 14% efficiency will take up about the same amount of roof space as a 210W panel at 15% efficiency, but at a lower cost/W. In most cases, the customer’s cost/W is the more important factor; the best cost/W will be found in the lower efficiency ranges.

Power production

When a PV system does not produce the expected amount of power, the cause is often traceable to the original system specifications and design that were proposed during the sales process.

Most power production problems seem to occur not as a result of faulty installation, but rather as a result of faulty expectations or faulty design. These kinds of problems are mostly created during the specifications and design phase leading up to the sales proposal, and are most often the result of cost-cutting mixed with an effort to indulge the customer’s aesthetic considerations, without full disclosure of the ramifications. The customer doesn’t want the panels on the front of the house (which is the south-facing, best location), for example, or says “it looks better over there” — right where a telephone pole casts a small shadow that travels across the row of panels every afternoon as the sun moves (of course the pole can’t be removed).

Partial shading of a panel or string of panels can dramatically reduce the performance of the array. Within each panel, if a single cell is shaded, its lowered performance will cause a bottleneck effect that lowers the output of all other cells to match it. Within a string of panels, a shaded or partly shaded panel has the same bottleneck effect on all other panels.

Mismatched orientation causes the same effect. If some of the panels in a string face in different directions or have differing tilt angles, all of other panels in the string will drop production in real time to match the lowest performing panel of the moment. There must be a separate string used for each angle and tilt used.

It is important to show the customer much more than the rated output peak of the system. It’s far better to do a conservative calculation of average output considering all of the factors including temperature, sun angles, transient shading, inverter inefficiencies, etc. A proper calculation will ultimately be confirmed by measured production just a surely as an overstated capability will be noticed and challenged.

There are many other sales and preliminary design issues that must be considered, like string sizing, inverter selection, logging and monitoring capability, cosmetics and aesthetics, tax credit and rebate issues (and surprises). We hope to address many of these topics in future articles.


John Williams is COO of Solar Panels Plus, 533 Byron Street, Suite E, Chesapeake, VA 23320 USA; ph.: 1-757-549-1494, e-mail: jwilliams@solarpanelsplus.com

.via Solar PV installations: Beyond “measure twice, cut once” – Photovoltaics World.

Glitter-sized Solar Photovoltaics produce competitive results

Glitter Solar Cells

Glitter Solar Cells

By Neal Singer, Sandia National Labs

New Mexico, United States [RenewableEnergyWorld.com]

Sandia National Laboratories scientists have developed tiny glitter-sized photovoltaic cells that could revolutionize the way solar energy is collected and used.

The tiny cells could turn a person into a walking solar battery charger if they were fastened to flexible substrates molded around unusual shapes, such as clothing.

The solar particles, fabricated of crystalline silicon, hold the potential for a variety of new applications. They are expected eventually to be Read More… »

New Silicon Energy solar system at Franklin PUD

Check out the new solar system at the Frankin PUD. In this video, solar designer Jonathan Lewis interviews Todd Blackman of Franklin PUD, who shares his observation that their large solar system is so well integrated with the rest of the building that customers walk past the huge solar curtain wall solar array without realizing it.