Waiting for tomorrows solar technology by Coastal Solar
Everyone thinks there is some super module just around the corner. What is never mentioned in the nightly news or newspaper article is that though there are scientists creating high efficiency modules in the lab they have been doing that for decades. The high efficiency solar module is not something that is close to being discovered because its been around for long time. The advancements that are changing the industry are in the manufacturing processes. Making higher efficiency modules cheaper, longer lasting and more consistent.
Some manufacturers are experimenting with Thin Film technologies. These typically have a warranty about half that of a Polycrystalline or Monocrystalline module because the Thin Film structure is not as stable, furthermore its much less efficient and usually not ideal for rooftop installations since it takes more space. One newer highly successful technology is the evergreen string ribbon modules which are very efficient polycrystalline modules that are manufactured using in a continuous process which results in a \”string ribbon\” or solar cells.
These are the types of advancements that are likely in coming years; incremental improvements in efficiency and processes. Keep in mind there is a lot of money and interest being invested into the solar markets. It is predicted by most to be the next boom. Manufacturers are working hard in China, Korea, Japan, Germany, USA and other countries all competing to have the best module and/or the best price.
If you have any doubt about the amount of competition to have the best module look at this list. http://www.gosolarcalifornia.org/equipm … odule.html This is the California Energy Commissions list of approved modules for the CSI rebate. There are 1,605 different models available as of March 2010. If there were a new technology that would revolutionize the market on the brink of debut these companies would be all over it. Furthermore, before a manufacturer invests money into tooling and equipment necessary to be competitive, they do extensive research. These manufactures would not be getting all tooled up for the current technology if they had any reason to believe that something new could render their current equipment obsolete.
That said there have been some interesting developments in inverter technology. Residential and small commercial inverters remain at about 95%-96% efficient and that is not likely to improve by much. The inverter is always going to consume some energy and with smaller systems this will probably make up a few percent of total output no matter how advanced the technology. The biggest advancements on the horizon are in two areas; Monitoring and MPPT (which is an acronym for Maximum Power Point Tracking).
A newer model on the market is the Enphase inverter. The Enphase system uses a single inverter for each solar panel. The wiring from one inverter to the next and down to the meter is 220VAC. The primary advantage to this system from a practical standpoint is that each panel has its own MPPT. That means that should some of the panels be exposed to different conditions than the rest, each inverter will be able to adjust to maximize its panels output. Partial shading or different angles are the two main reasons where you would see a marked improvement from a standard inverter to Enphase.
For instance if you would like to place some panels on the south and some on the west you will greatly improve your system output with individual MPPT. Also, should your array have some shading, the individual MPPT will enhance output significantly making sure each panel generates its maximum wattage at all times.
The other primary advantage of these systems is individual panel monitoring. Enphase has a web portal where you can view nearly every imaginable aspect of your systems performance and production history for the entire array and each panel. It really is remarkable. However, it does little to improve your system performance. The primary performance enhancement would be early detection of a damaged module. Since modules are fairly robust it is likely that most will never use this feature but it is nice to know that all modules are performing as expected.
There are other technologies that provide individual monitoring and MPPT with a conventional inverter. TIGO makes a DC to DC converter that separates the modules similarly to the Enphase, however, they do not convert the power to AC grid power, this is still achieved with a conventional inverter.
As awesome as these technologies appear, in all reality many customers would be better off with a conventional inverter. The reason being that most people aren’t likely to be glued to their computer screen day after day in awe of their solar systems output data. If you don’t have shading issues you will see a faster return on investment from a less costly conventional inverter. If you are willing to pay a slight premium for the fun of it by all means. Just keep in mind that the real purpose of a solar array is to spin your meter backwards and it should last a long time and pay for itself in a short time, otherwise why spend the money. Your safest bet is tried and true technology manufactured by reputable companies that will be around to stand by their warranty.
To sum it all up grid tied solar has been around long enough that all of the kinks are worked out and the technology has progressed to a point where it is reliable, efficient and affordable. Panels will get better but so will televisions, cell phones and computers. At some point you simply have to pull the trigger and make that investment. Especially since your system will probably pay for itself well before affordable solar modules reach 20% efficiency.
Don’t forget… That rebate is not going to be there forever. As of March 2010 there is only 7.38 out of 21 MW left for the $1.90 per watt rebate. The next step will be $1.55 per watt. This decrease represents about 15% of the current cost of solar modules. So unless solar panels increase by 15% efficiency or decrease by 15% in cost before the rebate goes down Now is a great time to GO SOLAR!
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