Buying solar panels and alternative energy on eBay.
Unfortunatly, due to eBay's simplistic editing tools I have not been able to update this article. The most current version of it as of May 2010 can be found on w w w.vandwellers.org/solar/buyingsolar.htm
I’ve brought one large and two small solar panels on eBay, but I have brought a total of eight solar panels in the past two years, not including small ones for trickle charging batteries and solar garden lights. I have researched them a lot, and have decided to share some of the things I have learned here. Please note this article deliberately does not go into detail on things such as how many panels would you need for your solar power system as that information can be found else where on the Internet, and it depends a lot on what you want to power.
It should be noted that solar panels are also known as solar cells, photo voltaics, PVs or solar power. Also, I am generally referring to large solar panels here, not small battery trickle charging ones or ones used in solar lights. Almost all of the information below refers to large solar panels. These do not include small ones below about 55 watts.
How much should you expect to pay for your solar panels?
Large solar panels usually sell for less than $10 per watt. So the most that you should pay for a 60 Watt panel would be $600. In reality though it tends to be even less than that. For example, looking on eBay just now I see a Uni-Solar 62 watt panel selling for $569.00 and a Sharp 80 watt panel for $650, both buy it now prices. These are typical prices. Generally the more watts you buy, the less you should pay per watt. Small panels less than 5 or 10 watt will typically cost about $10 per watt. However, prices are coming down. All prices are in Australian dollars.
2 words of warning
I have noticed that some sellers are now selling their panels, particularly smaller ones at just below $10 a watt, but include postage that takes the overall price well above $10 per watt. The total price should not exceed $10 a watt. There are several Australian solar panel dealers like the Rainbow Power company that will sell you panels for below $10 a watt. Even low capacity panels down to 5 watts should cost no more than $10 a watt. Only the really small ones should cost more than $10 a watt as below 5 watts economies of scale don't make it economical to produce say a 1 watt panel for $10.
Another thing I have noticed is that some panels are being quoted at higher output than they actually produce. A mate from work asked me to test the power output of a panel he had brought online that was quoted at 20 watts output. I measured the voltage and amperage output of the panel on a sunny day with the panel directed straight into the sun. I tested the panel under full sun, at heat and after I cooled it. It never produced more than 13.8 watts at 18 volts After contacting the manufacturer, we were advised that particular panel was not capable of producing 20 watts. It was rated at 14 watts at 22 volts. In other words, it was never capable of producing anything like 20 watts at 12 volts.
Many solar panels are rated at their maximum output at maximum voltage. A typical 12 volt solar panel will actually produce voltage of up to 24 volts. This is one of the reasons why power regulators are needed. At 24 volts the panel produces peak power at peak wattage. When regulated to 12 volts, less power is produced. The question to ask the seller then is, what wattage does the panel produce at 12 to 14 volts? As this voltage range is usable.
I've simplified things there a lot, but that information should help you get the actual useful output of the panel, not the so called 'maximum output' that a lot of manufacturers and sellers quote.
I just brought a small 20 watt panel this year from a great seller who shipped it with brilliant packaging. Testing this new panel shows it easily produced 20 watts (actually made 21.2 watts) in bright sunlight. So please note that there are definetly some great sellers here on eBay. If in doubt about the seller, check their feedback, just the same as buying anything on eBay.
Things to know about large solar panels.
Most solar panels are rigid and will come with the nuts and bolts to mount them on to a roof or frame. Almost all will come with junction boxes for wiring them up.
How long can I expect my panels to last?
20 years or more. Some have 25 year warranties. Certainly some panels have been in use for greater than 25 years in Australia. Almost all large solar panels will come with a 20 year or more guarantee. If they don’t, ask for one or consider buying elsewhere, particularly if the brand is unknown. Some flexible panels may not last as long as rigid panels, mostly because they are used at sea which is a tougher environment than on land. Small panels tend to come with limited guarantees.
Solar panels tend to be weather proof. They typically will handle rain, light hail and winds. I have heard of some handling impacts from golf ball sized hail stones. Smaller solar panels such as those used in battery trickle chargers may not be weather proof.
How much solar will I need?
On a small set up like my campervan I have three 64 watt panels and an 80 watt panel providing power to a regulator which charges two 100 amp hour Absorbed Glass Matt deep cycle batteries. I know that’s a lot of jargon thrown in there but in plain language I get about 260 watts of power at 12 volt fed into a 200 amp hour battery bank. I loose a few amps due to losses in the system. Now that’s for most sunny days. On overcast days it is less than that. That system will power my small 42 litre 3 way fridge, an mp3 player for a few hours a day, a 55 cm television and a few lights for a few hours a day. During the day the solar panels will both provide power to the fridge and charge the batteries so the fridge will run at night. The television is powered through a small 300 watt modified sine wave inverter that makes 240 volt out of 12 volt. This is a typical small solar power set up. The various bits are explained in more detail below. It cost me about $2,500 for the 4 large panels, $200 for the deep cycle batteries, $129 plus postage for the regulator, $69 for the inverter and about $100 for the cabling and many fuses which are built in to the system.
Solar panels on my campervan.
While I have researched solar power a lot, I am not an expert on larger solar power systems. I can not really make recommendations on what would be right for you. But I can recommend a nice book that will give you the information you need. Collyn Rivers series of books on solar power for motor homes provides some great information on sizing solar power systems. The books are written in Australia, for Australian conditions and Collyn is a qualified engineer with lots of experience in the field. There other good books out there too. A lot of solar shop web sites here in Australia also provide information on sizing a solar power system. Remember that other factors such as where you live, and where and how you mount the solar panels will determine how much power you can get out of them.
One big user of power is microwave ovens. They gobble power. Unless you are looking to spend around $10,000 to $20,000 on a large power system for a house you should probably forget about powering a microwave oven from a solar power system. It will need large and expensive battery banks and inverters just to power it and will use up a large fraction of your power. You’re better off with a bottled gas powered stove.
Will you need a regulator?
Yes, if you are dealing with large panels, you will generally need a regulator. Generally if your solar panel can fully charge your batteries in a day or two then you will definitely need a regulator. A power regulator takes the power from your solar panels and regulates the feed into your batteries which can be used at night or when there is no power coming from the panels. The prime role of the regulator is to make sure the batteries are not overcharged. Many regulators also prevent your batteries from becoming too discharged and will prolong the life of your batteries.
I brought a very nice unit which sells on eBay a lot. It is a 12 volt regulator able to handle 20 amps of power, has an LCD display and 6 input leads. It is generally called a PV charger, and is the BBC-7120 model. The good thing about it is that it is programmable for different types of batteries and battery charge voltages. This is very important as you buy a cheap regulator it may want to charge your batteries up to a greater voltage than their maximum allowed charge. Also, some batteries like Absorbed Glass Mat (AGM) don’t like typical charging regimes and may be slowly destroyed by a cheap charger. Typically if you have a large set up which has at least 60 watts of power generating capacity you are far better off using a programmable type regulator, particularly if you have expensive deep cycle batteries.
If you have a smaller set up that has less than 60-80 watts of generating capacity then a straight forward non programmable type regulator might suit better. Particularly if the system charges a large battery or is infrequently used.
Some circumstances when you would not need a regulator are when your system has no battery or where the solar panel or if it is designed to slowly charge a large battery. Some systems with no battery might include a solar powered water pump in rural areas which only pumps water during the day, or as used in my campervan, solar powered air fans to ventilate the area during the day.
One important thing to note about regulators. Some are 'night light' regulators. They will only switch on power to a load when the incoming power is low, such as at night. These are good for controlling lights at night, but no good for use in alternative energy applications.
What sort of batteries should I use?
Deep cycle batteries will normally suit your system best. The capacity of the batteries will depend on what you want to power. I would suggest that you do a bit of research on solar panels and deep cycle batteries but I can suggest this: All research I have done has suggested that your battery should not be of too much capacity that your solar panels can not recharge them properly after being discharged over night. Flat or low charged batteries will not last as long as fully charged batteries. Regularly flattening the battery will dramatically shorten it’s life. A low voltage cut off or a regulator with built in low voltage cut off is a must and will save you money and inconvenience in the long run.
How can I get more power out of my panels?
It is all done with mirrors. Literally, reflect more light on to the panels. If you can set up reflectors that reflect morning and / or evening light on to your panels you will get more power out of them. You might not want to do this during the hotter parts of the day, but certainly a few sheets of polished metal may be a cheaper alternative to buying extra panels. I’ve seen it done on a small scale, and read of it being done on a larger scale. Don’t expect miracles though. Twice as much light will not equal twice as much power. Also, I think there would be a limit to how much extra light you could reflect on to a panel before it became a solar furnace and went up I smoke.
Know your product - Solar panel manufacturers.
Here are a number of companies that I have seen who have manufactured solar panels that are sold regularly on eBay:
Uni-Solar panels are manufactured in Mexico and California. Their panels are typically larger than most other panels of the same wattage. The Uni-Solar panels are also well known for their shade resistance through the use of bypass diodes. In plain language, if part of the panel is in shade the unshaded portion of the panel is better able to pass along it’s power than pretty much all other brands of solar panel. They also perform better than most panels as they get hotter. Almost all other panels become less productive in the heat. This makes them well suited for mounting on campervans, motor homes and caravans. The Uni-Solar panels are also pretty tough. I’ve read reliable stories and seen pictures of Uni-Solar panels that have come off car roof and still been useable.
Uni-Solar produce rigid panels and flexible ones. That’s right, solar panels you can roll up. The large rigid 64 Watt solar panels usually sell for $590-$640 (plus shipping), depending on demand and availability. There has been a supply issue with them in the past but I think that has been resolved. Smaller flexible panels are more expensive per watt. These are the only large panels that I would recommend paying more than $10 per watt on. The flexible panels are used a lot for marine use such as sailing boats as they are very weather proof.
My personal experience with the Uni-Solar panels are that they have been reliable, easy to maintain and produce good useable power. They are also easy to wire up, having a large junction box for easy wiring. I have had no issues with them. They work fine.
I think that up until recently Sharp was the largest manufacturer of solar panels in the world. Their technology is mature, as they have had a lot of experience with making solar panels. Generally Sharp make panels in the 80-120 Watt range, with a few smaller ones. They make rigid panels only. Their panels are easily recognisable as they tend to have square cells that cover the entire panel surface.
I have brought a 55 Watt Sharp panel in the past and had no problems with it. I can certainly recommend them. Most Sharp panels are manufactured and used in Germany where there are some pretty impressive solar power stations.
Suntech is a relatively new beginner in solar power manufacturing. They are a joint Australian - Chinese company created by a dual nationality Chinese-Australian, DR Zhengrong Shi. Although they are new, their solar panels are top notch, and they offer the standard 20 year guarantee on their panels. They produce rigid panels from 2-165 watts
I have an 80 Watt Suntech panel mounted on mu campervan. It has performed well, and I have had no issues at all with it in over a year.
BP is one of the oldest producers of solar panels. Some of their panels have been in use in Australia for 20 years or more now. They tend to produce high wattage solar panels between 80-220 watts. Their panels still tend to have a bit of a retro look with lots of small round photo voltaic solar cells. I have no experience using these panels but I know people who have, and they have not had problems with them.
Unfortunately their links to their Australian web site’s solar products does not work.
Kyocera have been selling solar panels in Australia for at least 5 years. Apart from their web site, I don’t know much about their panels. I don’t know anyone who has brought one, so I have nothing either good or bad to say about their products. They do sell a lot though and I’ve heard nothing bad, so that is a good sign.
What about these double sided space technology solar panels?
I’ve seen a few of these on eBay recently. I don’t own one, I don’t know anyone that does. However, logic suggests that unless you have a set up that reflects light on to both sides of them, they will only get light on one side. In truth I expect that all solar panels that were mounted in glass without a non transparent backing would work this way. Until I test one of these I am a bit sceptical. If the panel is mounted in glass with no backing it may be more fragile than a normal panel. Still if it comes with a 20 year warranty, maybe it is worth a try, provided the company that makes them will be around in 20 years.
Other forms of alternative / remote area power.
These are generally new to the market but are coming down in price. Wind turbines and wind generators generally will produce more power than solar panels. Typical small systems will generate about 200 watts of power. That is more than my 4 solar panels put together. These units are small, light weight and reasonably easy to set up. I have seen one of these set up as a demo model. It certainly managed to produce a lot of power. One problem with them though is that unlike solar panels they have moving parts and will require maintenance.
Wind generators come in much larger sizes though. 24 volt 700 watt models can be brought for under $1000. This represents much better value for money if the wind generator is able to provide power at a steady rate. Wind generators will not generate power if there is no wind, but unlike solar panels, they can generate power at night.
Petrol / Diesel Generators.
You might think that generators are not exactly alternative power, but they certainly are useful remote area power. You should not rule them out. Particularly as a small generator could provide you with all your power needs. A small generator of reasonable quality could cost less than $200. Considering that four solar panels might cost you about $2500 that would leave a lot of money left over for fuel to run the generator. Generators however usually don’t last 20 years. They require maintenance, refuelling, repairs and eventual replacement. They are also noisy. However, they provide almost the only reliable guarantee of power when you need it provided that they are well maintained and fuelled.
Things to look out for:
As per usual beware of adds that don’t provide direct and clear information. Generally solar panels and wind generators will be rated by the number of watts they can produce per hour. Some times they are rated in amps. Be aware of units that measure their output per day as this could be for a 24 hour period, or for a specific day of the year. Also, beware of brands you have not heard of. Do your research and use the Internet to find out more about what you are planning to buy.
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