Going solar is a fundamental decision. It is not just about saving some money in the long run. It is a lifestyle. Although the solar industry has come a long way and is now very well developed, it is still in an experimental stage.
Tips On Buying And Installing Your Solar Electrical System
Adi Pieper | ADI Solar Electric
by Adi Pieper, ADI Solar Electric
Many people are very interested in solar electrical power as an alternative or a back up for their grid power. However, too many of them believe that it is simply done by "throwing" a couple of solar panels on their roof and switching over to solar. Many e-mails I receive reflect this way of thinking, and it often takes quite some time and effort to educate these people on what is really involved in this process. I wrote two informative books on this subject: The Easy Guide to Solar Electric, For Home power systems (ISBN 096718911X) as an introduction and the follow up: The Easy Guide to Solar Electric, Part II, Installation Manual (ISBN 0967189128), which are widely available either through your book store, amazon.com, or my web site: www.adisolar.com. In these books I point out that "it ain't that simple", however, it also is not as complicated as your local solar installer wants you to believe.
Before you make any decisions which way to go you should inform yourself of all the options available. If you have grid power nearby or already live on it, contact your power company and ask about the procedures and costs involved. If you choose to go this route you most likely need a licensed solar contractor to install and permit the system.
When choosing a solar contractor investigate carefully. The size of the ad in the yellow pages is not always indicative of the quality of service and, of course, the ad has to be paid for by someone, which is you, the customer. Get bids from different contractors. Get recommendations by people who have dealt with these companies. Solar Suppliers and Contractors often have special dealings with wholesalers who push certain brands of equipment which may not necessarily be the best option for your situation. Compare the equipment list you receive with that from other companies to see which components can be truly compared with each other. You also may want to ask questions why certain equipment is been used. You may not need a Rolls Royce if you are living at the end of a dirt road!
But let us look at some of the equipment that is involved in your future solar system.
The Solar Panels
Let's start with what to buy and where to buy. The first things that come to mind are the solar panels. Before we get into the details let's have a quick look at global solar business practices. The solar product manufacturing industry seems to be a "stop and go" system, like holding the brakes while applying power. Who would have guessed that two of the main solar panel manufacturers are the same companies who oppose solar power because it directly competes with the fossil fuel and other products they are selling; BP (Beyond Petroleum) and Shell ( who owns the Siemens line). Other big corporations also had their own agendas when taking over solar panel production GE (Took over Astro), and Kyocera (Japanese company, the world 2nd largest panel manufacturer, tries to dominate the world market).
While solar product prices, especially for panels, went down over the past years, they now are in a sharp rise. The reasons for that are twofold. For once there is a great demand from Europe (where energy prices are skyrocketing), to buy every single panel on the market for about twice the price we pay in the US, and secondly, some Japanese companies try to buy all the raw materials to produce solar panels available on the world market, probably to control the market. (I was told by a manufacturer that they just can't get the raw materials for their solar panels and hence have a big back log on orders that they would have a hard time to fill even if they had the materials). So, when purchasing your solar panels, you want to shop around. Retail prices for single crystal panels are about $6 per watt, multi crystal panels are around $4.50. But let's look at what we are talking about.
When it comes to solar panels, there are three basic types of panels available:
Single crystal panels are the highest in quality and efficiency, which work very well under semi-sunny conditions, like in coastal regions and in northern regions where the number of sun days are minimal.
Multi-crystal panels are a little less efficient (up to 20% less), but they are also less expensive. If you live in the "sun belt" you might do just fine with those.
BP, Siemens, Astro, Evergreen, Kyocera are some of the manufacturers of both types of panels. In addition, Photowatt which only produces multi-crystal is an excellent brand.
Thin Film Panels, the third type of panel construction, is called Amorphous Film Technology. These panels are far less efficient, and their life span is much shorter. They often are flexible and find their application on boats, cars, RVs etc.
In addition to the latitude you are living in, your solar system voltage also determines which panels you need to purchase. Smaller panels between 50 - 100 watts come in 12 volt panels, while bigger panels 120-175 watts are typically 24 volt panels. In the end it all depends on the combination of location, system requirements, and budget.
Rack it or wreck it, (or wrack it or reck it!!) You need to mount your panels onto something that holds them in place. "Fixed racks or trackers"? is often the question. A fixed rack continuously points the panels to the south, with the ability to adjust the angle for the seasonal position of the sun. A tracker moves with the sun from east to west giving the panels best exposure to the light. Two types of trackers are available, the "gas powered" and the electrically powered ones. The frame of the gas powered is filled with gas which, through heating by the sun, moves the rack east to west. The electrically powered trackers are often two axle trackers and move east and west as well as up and down giving the panels the ultimate angle to the sun from dawn to dusk. Prices for trackers vs. fixed racks are four to five times higher. If you live in the sun belt you may buy extra panels for the price of a tracker and come out ahead with your charge power. In the northern regions you may opt for a tracker to "squeeze" every watt out of every sun ray.
Another main component in every system is the Inverter. This device converts DC to AC power. It takes your low voltage from the batteries and creates the 110 or 220 volts AC that most households work on. Pure DC systems are rare in this day and age, there are simply not enough appliances available for that. Two types of inverters stick out, the True Sine Wave (TSW) and the Modified Sine Wave (MSW) inverter. I spend a whole chapter on this in my book. Let's say this much: The True Sine Wave Inverter delivers very clean electricity at a considerable higher cost than the Modified Sine Wave Inverter. Most appliances run fine on the MSW Inverter. If you run special sound or video equipment, you may want to stick to the TSW inverter. Some appliances, e.g. certain washing machines or dish washers, may have problems with the modified wave form. Most of the high wattage inverters, 4000 watts and above, are of the TSW type. Also, all grid inter-tie inverters need to be of the TSW type.
There is also a possibility that you combine the two inverter types in one system. If you only need a true sine wave for certain small applications you may buy a small inverter for just those, and then put the rest on a cheaper modified sine wave inverter. Exeltech manufacturers these TSW's in all sizes. The smaller ones, between 500 watts and 1100 watts, are rather simple (one could almost call them primitive) but deliver an excellent sine wave. Be careful though where you place them, most of them develop a high pitch sound over time which is hard to get rid of. Also, if you overload them, be prepared to take them completely apart just to change four automotive type glass fuses, while all other inverters have simple reset buttons for this occurrence. This poorly designed feature, by today's standards, only be called primitive.
The main contender on the inverter market, formerly known as Trace, is Xantrex, with great products and a well-established repair network . A knock-off inverter under the name, Outback, is higher priced but preferable over the trace for certain conditions.
Inverters for grid inter-tie only usually accept higher DC input voltages (120 - 200 volts) directly from the solar panels without the use of a battery bank. Like the Sunny Boy or the XantrexGT3.
The Charge Controller is a sore subject with many installers. Two types dominate the market: The Multistage Controller and the Power Point Tracking Controller. The latter one is called PPT, which through an ingenious design, delivers 15 to 30 per cent more power then the former type. The price on the PPT controller is roughly twice of the Multistage, so it may or may not pay for you to have that extra performance. The PPT controller performs best in cold climates or when extra length of cable from the panels to the rest of the system is required. Blue Sky with their Solar Boost Controller is the most affordable - or one of the biggest PPT manufacturers in the US. Another manufacturer is Outback, again with fancy housings, a bit pricey but with excellent performance.
Some of the brands of Multistage Controllers are Xantrex with their C series, which come with an optional monitoring front for voltage, amps, and amp-hrs. Morning Star has excellent Multistage Controllers with automatic equalization and monitor, as well as load control up to 30 amps.
If you choose a system with batteries, (as opposed to a grid inter-tie system without batteries) now is the time to scratch your head, because many options are available. If you need batteries for a stand-alone solar system, it has to be a full-size battery bank with a good reserve for 3 - 5 days. If you need batteries for a grid-inter tie system, you may opt for either a full size battery bank, which supports your whole load with a good reserve for cloudy days or you opt for a small bank which only supports your home for a short duration, hoping the power will return in due time.
The deep cycle lead acid battery is the type most commonly used in a solar system. Other battery types, such as Alkaline and Ni-Cad are still too costly. Of the lead acid batteries, both the gel type and the glass mat-type are service free. However, they tend to be a little more sensitive and often don't last as long as the flooded type lead acid battery, which requires maintenance.
Batteries come in many sizes. A very commonly available size is the "golf cart battery" or the T-105 type. At 6 volts with 220 amp-hour, you need to connect several in series and parallel to create 12 volt or 24 volt systems. They are relatively inexpensive and very robust and last about 5 years. But they are only recommended for smaller systems. If you plan for a bigger system you may need so many of these that you run short of storage space. There are several disadvantages of having too many batteries in a system:
- Too many interconnects - which can amount to additional electrical resistance,
- more connections will corrode and need to be cleaned, and finally,
- a lot of caps need to be opened to check and refill water on these batteries.
The next bigger size is called the L-16 batteries. (These names derive from the Trojan brand and have been accepted as the generic names in the industry.) L-16 batteries range between 350 amp-hours and 420 amp-h. Also rated 6 volts, these batteries are taller than the T-105s but take about the same real estate in your battery box. These are also very robust batteries, however, you do not want to discharge them too low too often, so size the battery bank accordingly for a daily discharge of 20% to 30 %. (I was told by one battery technician, that these batteries should not be 80% discharged more than three to four times a year.) Their life expectancy is about 8 years.
The next size up are what is called the fork lift batteries. These are very tall and very heavy batteries, often housed in steel cases. Many manufacturers of these batteries now produce them especially for solar application, which is slightly different from industrial machine application, that they don't need to be fully recharged every day. The price range of these batteries is in the thousands of dollars for a complete bank. Since they come as 2 volt cells, usually six in one steel box, you need to buy enough to create the battery size of your system, e.g. 12 volt, 24 volt, or 48 volt. And while these batteries come with a substantial warranty you need to be sure to document the service on these batteries as well as using the right type (A manufacturer turned down all warranty claims because the battery in question was designated as a fork lift battery and not as a photovoltaic battery which has other service and charge requirements). Make sure you choose the right battery and keep a service log when adding water.
Whatever your choice of battery may be, keep access and egress in mind. All too often, when a battery bank had to be replaced, it turned out that walls, doors, closets, etc. have mysteriously appeared in the exit path of the batteries. So, buying a battery bank that last its time saves you on carpentry, labor, and chiropractor fees.
Cheap batteries, as available in department stores, don't pay in the long run, but might be all you can afford at the time. Brand names like Trojan, Exide, Surrette, are commonly used for solar application. Deep cycle marine batteries are usually too small because you would need typically twice as many of those compared to the golf cart batteries.
Combiner and junction boxes as well as disconnects are all substantial part of each system. This can be a simple circuit breaker box for under $100 or fancy Power Panels climbing into several thousands of dollars. The big load centers or power panels combine fuses, disconnects, monitoring equipment, and charge controllers in one box. They are recommended in bigger systems and are well worth their money.
In smaller systems you can get by with separating the individual components. For example, monitoring equipment often is included in charge controllers. For disconnects you can use conventional breaker boxes. However, there is only one brand of circuit breakers available that fits into conventional breaker boxes which is rated for DC connections; this is the Square D QO type breaker. The fact that most inverters have a on off switch technically fulfills the need of a disconnect between the batteries and the inverter output (Inspectors do have split opinions on that.) A T-grade fuse between the batteries and the inverter will protect the inverter. There are many other "tricks of the trade" that would extend the scope of this article (that's what books are for). Also remember, that the size of wires typically used in a solar system demands a lot of copper which is in great demand on the world market. The price for your wiring alone can reach several hundred dollars.
To Self-Install or Not
This is a controversial subject and I have been criticized for my support of self-installations by the experts in the solar industry, since it's bad for business, and perhaps compromises safety.
The basic question is what the Law has to say about it. In general, the authority having jurisdiction over the state you live in will determine what you can do yourself. Many states do have laws permitting home owners to build their own home which includes, at times, doing all plumbing and electrical work themselves. Call your CID (Construction Industry Division) office and inquire. Of course, I cannot say in this article that you just may go ahead and do the work yourself, without any authority looking over your shoulder, especially if no inspection is required. That would be illegal.
But should you do this, you do not want to wake up one sunny morning finding the four walls around you lying in ashes. DC power is, in a way, more dangerous than AC power when it comes to fire hazard. Usually it sparks and arcs stronger than AC power. Connections have to be firmer, switches have to be designed for it as well as circuit breakers. In addition, there are not as many electrical components readily available for DC wiring than for AC wiring, and so many self-installers tend to use non approved parts which may not withstand the power of DC. Again, to shamelessly promote myself, I dedicated a whole book on this subject.
If you need to work with an inspector be prepared to produce excellent workmanship as well as using the right wires, connectors, pipes, and breakers. Make sure all equipment that you buy is UL (Underwriter Laboratories) listed or it won't be accepted by the inspector. Some of the cheap or used solar panels and other older components sold by on-line companies are often not UL listed, so check that out before you buy.
There can be a nice compromise between total self-installation and contractor installation which I exercise quite often. I let the willing customer do as much as I feel he or she can do and then take on the rest and the responsibility. This way both sides are happy, the customers know a lot more about their system and I still get to make some money. After all who really wants to dig trenches, break through walls, and pour concrete foundations for arrays?
If you completely let a contractor take over your solar system, you want to make sure that you understand what he/she is selling you. You want to be actively involved in the planning and designing phase or you end up with a system that you may never understand and/or you may not want. After all, you have to live in your solar home and not your contractor. Do not let the contractor "belittle" you when you do not understand something. Arrogance is a widespread disease and often covers the fact that the person involved does not understand certain things themselves.
Going solar is a fundamental decision. It is not just about saving some money in the long run. It is a lifestyle. Although the solar industry has come a long way and is now very well developed it is still in an experimental stage. Unfortunately, even big solar manufacturers use the market as their testing ground and the customer as well as the installer have to bear the burden when things do not work out. "Just bring it in to the shop" is not an appropriate response when your components do not work, and you have no power for days or weeks and you must travel hours to the solar supply place.
But on the whole, things are looking up. In spite of a hostile administration in Washington, the solar market is growing and many states offer incentives to go that route. Power companies now are realizing that they can hardly put up with the power demand and have become more friendly towards grid inter-tie systems. Transmission lines are ugly, dangerous, and a total waste of energy. If more local communities and private home owners would use renewable energy we, as a country, would be safer, less vulnerable, and have fewer wars to fight.
Adi Pieper is a native of Germany but has lived and worked in the U.S. since 1985. Since 1991 he has worked in the field of Solar Electric near Santa Fe,New Mexico. He is an electrical contractor and the president of ADI Solar Electric. He also teaches classes about Solar Electric at the Santa Fe Community College and the Santa Fe Ecoversity. He has published tow books on solar, The Easy Guide to Solar Electric, For Home Power Systems, ISBN 096718911X and The Easy Guide to Solar Electric, Part II, Installation Manual, ISBN 0967189128.
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