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I purchased two of these kits (8 panels) and mounted them on the top of my RV. I have had them on the top of my RV now for approximately 8 months.
When I received the units, I tested each of them for the open voltage measurement noted in the instructions with a digital meter and found each to be producing 21 volts unloaded. Encouraged that the panels were working properly, I went ahead and took the time and expense to mount them to the top of my RV.
After 8 months, here's what I found:
First of all, the 15 watt, 1 amp peak output rating that Sunforce advertises is not correct. The peak output rating for each of these panels should have been advertised at approximately 750 milliamps per panel. The total peak output that one could typically expect from the 4 panels in this kit would be around 3 amps. 3 amps under perfect conditions.
I have noticed that the boards are extremely prone to large drops (upwards of 45%) in current output when they begin to heat up. In other words, the boards are VERY intolerant to high temperatures. But even under perfect conditions, the 8 panels that I have mounted on my RV only produced 6 amps, and I am in Hawaii.
Another problem: The boards shut down in lower light situations. In other words, early morning and later afternoon lighting, significant cloud cover, or other low light situation will be cause for either a total shut down of output, or the boards will be very poor performers in the low milliamps for 8 panels in parallel.
Within a very short period of time (about 4 months) the output from the panels gradually decreased by nearly 50%. And right now I am getting about 40% of the advertised peak output in perfect conditions.
The plastic construction is very cheap, in my opinion, and I am now worried that the plastic may break away around the screws that hold down the panels and fly off the vehicle. Needless to say, I am removing the panels.
I'm out some money, a lot of time and effort, but I've learned a lot about solar panel technology over the past 8 months.
For just a few bucks more, I will purchase a decent monocrystilline, 36 cell panel that will far and away outproduce the 8 panels that I have on my RV now, and take up far less space and be much safer on top of the vehicle.
Don't waste your time or money on this kind of solar panel technology. You will be very sorry.
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*Update* 6-2010, while my original panels are still running strong so long as I hose them down once a month, I've noticed that the PVC pipe provided to hold them in place has become brittle with sun exposure, hence I would now in 20/20 hindsight recommend a coat of Krylon Fusion Dover White Plastic Satin Spray Paint on the PVC parts to prevent UV cracking later in life. I do not think the Krylon Fusion product was available when I first setup my first panels but UV cracking of the support structure could cause panel damage in years 2 and 3.
Meanwhile Amazon got their hands on some obsolete & discontinued Sharp panels (12.5% efficiency vs the new 13.1% efficiency) if you are serious about needing lots of solar power in a small space, this is a big kit you can view it here: Sunforce 39126 246-Watt High-Efficiency Polycrystalline Solar Power Kit
My only concern about the kit is that due to the new panels being higher efficiency means it will be difficult to match panels if you find you still need more power later on. The other con on that system is it's price -$1300+ but you get the wattage, along with a cheap charge controller and inverter, both of which could be upgraded for better system performance. It's just another solar system to consider in the $5/watt or less pricepoint for DIYers.
Update 9-18-2008 Still going strong. I am very pleased with the summer power output of these panels. I wash them with a hose 1x/mo to keep the output current up. Measured before washing and after washing the panel efficiency is clearly a factor of how much dirt is on them. No problems long term on a roof though!
Update 2-20-2008 goes with graph "photograph" #3 above pink line is power and blue line is amps from the panel x 10 to share the graph. The X axis is panel voltage. Data was acquired using an Agilent dummy load with programmable voltage in 1V steps from 1V to 22V (open circuit voltage on the panel) on a partially cloudy day in winter sun. Expectations are for 2-3 times performace in summer sun provided the panels don't get too hot. These are on my house roof laying flat on a 3/12 pitch facing due south which is suboptimal but easy for me to do. Be sure to read the photo notes. Sorry about the colors excel defaulted to!
This is a MPPT chart (maximum power point tracking) you can see that the panels are optimized for charging a 12V wet cell right out of the box. Charge current turns on when battery voltage drops down to 13.0 VDC and turns off at 14.2 VDC with the supplied charge controller in the kit.
The only other interesting fact in 2 months is to keep your panels clean. My maximum current was 5.0 A on a cold morning with bright sun until it rained hard and washed the panels clean. The current went up to 7.0 A maximum right after the rainstorm. Below is the original review these panels have been running constant for 2 months now into 3 parallel deep cycle marine cells (315 AH) connected to the prosine inverter below to drain the energy made.
When reading the power/current chart you should keep in mind the amps have been multiplied by 10 so they use the same Y axis (so 20A on the chart corresponds to 2.0 A panel current) Watts are actual volts*amps. This was taken in the winter with partial clouds expectations are for a X3 improvement during summertime but its still february and I'm in the northern hemisphere so we'll have to wait and see. Basically an MPPT charger won't gain but a few watts with this panel so it's not a good investment unless you already have one laying around.
(Begin original review after buying panels)
I never seem to be overwhelmed by the latest shipment of product from China, but this one seems to show some promise and shows signs of good cost engineering and a complete design that can be set up quickly by one person with very little effort. I'd give it 5 stars if it were well packed, but my purchase turned into a shipping fiasco.
Most ALL solar installations are rated in $/watt much like new homes are rated in $/sq ft. We'll get to the sq ft bit later. Here you are getting 60W for 320 dollars or about 5.33 $/watt. Compared to a similar wattage panel, the BP solar 365U rated at 65W and priced (street) at 399 or 6.13 $/watt the amazon package seems to be a good deal when you consider it comes complete less battery (we'll hit that one later too)
In fact, the amazon package deal includes a xantrex 175 watt inverter with a .15A "idle" current designed for solar systems where current consumption must be minimized. It even includes a simple diode/switch "charge regulator" with 2 leds to indicate panel voltage and battery is full but lacks the ability to tell it what type of battery you are using (full is defined at 14.2 volts give or take so it's for wet/flooded cells). Neither of these are big buck items, but they do set you up for a complete small scale solar kit minus the battery out of the box, which is impressive.
Oh yes, the battery. I also ordered the duracell 480W inverter+28AH battery with this panel so I'd have a battery. Also made by Xantrex, it's a nice piece to complete the system. I made the mistake of ordering it with the solar panels (read on)
So how does China produce a complete kit for a lower $/watt price than professional solar companies like BP solar, GE, Kyocera, etc? Well it's the sq ft part we forgot about for a while. This uses 4 panels @ 15W each to get up to 60 watts with a simple parallel adapter included in the kit. The BP solar is one panel about the size of 1 of these 15W panels, or put another way, is 1/4 the sq footage. So if you are planning on covering your roof with these, think again because you'd need a really big house and have lots of 7A charge diodes and 175W inverters kicking around when you are done. The reason for the 4:1 size difference is the China panels are made using a silicon deposition on glass technique with a very thin film and correspondingly thin output, while other manufacturers use a silicon wafer production method that is roughly 4x more efficient in area, and somewhat more expensive as a result.
Ok now onto packaging. We need to get this from China to Amazon and finally to the consumer. On the first attempt FEDX carefully placed my fragile glass solar panels on the concrete then put 2ea 60lb batteries on top of them, cracking the glass on all 4 panels. After returning that to amazon, we tried again, this time without the batteries and shipping the system by itself. FEDX again noted shipment damage which wrecked 1 of the 4 panels, but running on 3/4 panels it does work, just not with full output. Amazon has given up because they will only ship and ruin something twice instead of making fedx pay up for piling 120 lbs of batteries on top of the glass panels and poking through the box & styrofoam the second time so I am still in negotiation with them about the shipment, however the product does deserve mention while I have it.
PERFORMANCE:
The design is actually quite well done. You can make (with 4 panels) a 12V (actually 15V) x 4A system, or a 30V x 2A or a 60V x 1A configuration depending on your power inverter and battery collection. For me, this will always be tied into a 12VDC bus so it is fine as shipped, but the flexibility is there if you have other voltages in use. There is no skimping on wire with 16 foot cords on each panel which helps to minimize power lost in the wire since each panel has its own cordset going to the combiner, after which runs are kept short. On a cloudy day I was able to get 2 amps from 3 panels (30 W) in full sun it peaked at 5.91A with 3 panels, so the Chinese manufacturing has under-rated their output as 90W from a 1/4 dead 60W panel in winter sun is doing very good I'd like to know how it performs in the summer!
As for mounting, a very clever system was designed to support the panels out of 1" PVC tubing with elbows and T's all of this is assembled with a singular bolt/wingnut style and the pipes have slots milled into them to ensure that the panels will line up one way or another without breaking after you get them. It has a prop-up leg system for use on the ground or can lay flat if placed on a roof that is already angled towards the sun. There isn't a provision for connecting multiple systems together, however you could make one out of sprinkler pipes you probably have.
All this really needs to be a well designed solar kit is 1) better packaging and 2) a battery. Even with 25% of my panels broken and removed from the system, it still managed to charge a car battery in under 1 cloudy winter day.
I'm impressed with the product, however disappointed with the shipper. I've also run up against Amazon's policy of two strikes and they are out meaning they won't negotiate for repair or replacement as the shipper on my behalf. I can return it alltogether or pay 100% for 75% of a system so it's probably going back tomorrow (monday) but my testing this weekend has shown that the product warrants consideration for people who
A) Need to keep their starting batteries charged year round (2nd cars, generators, etc) outside where AC power is not convenient.
B) People lacking A/C power somewhere and would like to run a small refrigerator (purchase a Xantrex Technologies Prosine 1,000 to 1,500-Watt Power Inverter #1000 TRUE SINEWAVE power inverter to run any motor load without damage) for 12V refrigeration needs its best to AVOID both inverters and peltier effect coolers ($40-80) and spend the money ($427 ouch) to get one of the Danfoss 12VDC real compressor refrigerators. The peltier coolers are just that coolers in a car they can keep something from your fridge cool, but the power draw of 8A x 12V (96 watts!) running continuously just to cool a 6 pack is insane. The danfoss iceless iceboxes can MAKE ICE if their compressor runs 80% duty cycle at 3A or about 24 watts. If you just want to keep 3 ea. 12 packs ice-cold and have a 2nd cool box inside for stuff you don't want to freeze they run 20-25% duty cycle on the 3 Amp compressor depending on temperature difference. Because I am on the road alot I keep one of these iceboxes with me attached to its own 80AH battery which will run it 3 days w/o charge. The same battery would run a peltier cooler less than 8 hours till dead. The battery is isolated from my engine but charges when I drive.
C) Or people who have *lots* of roof space and are looking at the lowest cost/watt installation complete with mounting hardware.
Don't forget the battery and don't have it delivered with your solar panels. As for emergency power, 60 watts won't do much for you but keep your generator battery charged and ready to go when the power fails. My natural gas genset is rated for 12,000 watts or 200 of these 60 watt 4-panel kits (800 panels) which would cost $64,000 and still not provide power at night, like the quiet genset does. With 12,000 watts I can comfortably run my whole house. Considering these natural gas gensets can be had for under $3000 they are clearly a great solution for whole house power backup systems so long as the gas stays on (most do propane or natural gas). I still like my friend's earthquake backup solution his house is heated by diesel and also has a diesel genset + diesel vehicle, so he is quite well prepared.
My use was to keep my seldom used 12VDC batteries all charged in the back yard. I kept the solar system for long term statistics and measurement and now have 2 of these in parallel. I bought a grid powered battery tender CTEK CTK7002 MULTI US 7002 Battery Charger to best charge my genset starting battery.
One last reliability issue having seen 5 broken panels now I can see an advantage to the professional panel systems these use the glass just as a cover & weatherproofing plate. The cells underneath are not damaged if the glass breaks provided the break is superficial. On the amazon system, the cells are deposited on the back of the glass, so if it breaks, by default so does the entire cell. A hailstorm could easily wipe out your backup power if using these monolithic inexpensive panels.
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The panels are installed on my garage roof, wired in to a battery bank and inverter which primarily functions as a very large (4KW) uninterruptible power supply for the house. So far, everything is working fine. They keep the batteries topped off without using power from the grid.
Like most manufacturer's specs, the 60 watt claim is hard to realize. The panels' current output is about 3.2 amps under bright sun, which yields only about 45 watts into a 12 volt gel cell battery at 14.2 volts. The panels can output about 20 volts which would indeed yield 60 watts, but not while connected with the included charge controller. A MPPT controller would achieve 60 watts, however.
The included controller is acceptable in that it works as advertised. One good thing about it is that it does not shunt the panels when the battery is charged, it actually opens the circuit, which means the excess panel output would be available for other uses. I intend to build another device for charging another set of batteries after the primary set is charged.
The included inverter works, but I did not use it in the system. Instead, I'll just keep it around for a portable inverter.
Also, I did not use the PVC pipe stand included with the system, instead mounting the panels directly to the roof.
The kit did include a variety of connectors allowing use with cigarette lighter plugs and jacks, alligator clips, and hardwire, but the charge controller is only usable if hardwired. I strongly recommend the charge controller be used, as the panels can easily overcharge most any 12 volt battery if a charge controller is not wired in.
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We bought this a few months ago. We live in Phoenix, AZ ("Valley of the Sun"), so this has plenty of opportunity to work. We have it plugged into 2 marine batteries (like car batteries, but bigger), and we have an inverter connected to those. The inverter is in the house, and the batteries are outside. The wire goes through the wall. We plug things into the inverter.
This was easy to put together. You have to buy the batteries, but this came with everything else.
I can run my laptop all day, as well as recharge the cell phones and Wii remotes. My husband can also run his laptop. If we only get on the laptops after work, we can run them well into the night. I've had to switch to grid power a couple of times if I've used my laptop all day, but I've never had to switch over if I've only used it during the evening. (This doesn't count the few rainy days we've had. Yes, once in a while it rains in Phoenix.)
This is not the most efficient solar panel set, but it's very good for starting out and learning about solar power. It's inexpensive enough to set up and charge all your rechargeable stuff whenever you need it, as long as you live in a fairly sunny area.
Oh, as an experiment, I plugged the vacuum cleaner into the inverter, which promptly started screaming for help. (The inverter has an alarm, apparently.) This whole set-up CANNOT handle this kind of power draw. You have to unplug everything and turn the inverter off and let it just sit a while and reset before plugging in your lower power things again.
You're not going off the grid with this set-up, but you'll save yourself a few bucks a month. And you get to be smug whenever anyone talks about going green. "Well of course, our solar array has lowered our carbon footprint considerabley. Shall we go for an organic smoothie now?"
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I am pourya, a PhD in power electronics and I design renewable energy systems.
You might not know how much 60W panel is.
A normal car battery is 100Ah which means for 100 hours it can provide 1 A. The voltage is 12V so it can provide 12*100=1200Wh of energy.
This panel is 60 W. reaching the nominal values for renewable sources are very rare. So we call this a 50W panel. After 1 hour it delivers 50Wh energy.
Now to charge our battery you need 1200/50=24hours of charging. Each day will give you 8 hours of good energy in texas. So you need 3 days to charge 1 car battery. ( but since you never fully discharge your battery, it might be 2 days ).
Now you should consider the rate of your consumption. If you want to use the battery simultaneously, it becomes very important that you consumption rate is below 60W which is basically a lamp in a car. So you are just discharging your battery and the panel is reducing the rate.
I don't have this unit. But I know the price is high. With 200-250$ you can get 200W panel not a 60W one.
