I am new to solar and intend to install panels on my house in Southern California. I have spoken with two installers. One recommends BP (200W), the other recommends Sunpower (220W). Their bids are comparable. There doesn't seem to be any "consumer reports" type review of systems. Can anyone give me advice on the best equipment to use (durability, performance, ease of working with the manufacturer, and equally as important, if these manufacturers are expected to stay in business)?

BTW, I don't have a ton of roof space available so I need to pack the maximum punch in the small amount of space I have.

Thanks in advance for your assistance.

i'll take a light stab at addressing this. both make good modules and have been around for awhile. it is difficult to predict who may sell out, go under, or continue on.
the sunpower is supposed to be the more efficient of the 2 and of most i'd say, but the drawback is having to have a positive ground and equipment for it. it is available as xantrex i believe makes their stuff that is positive grounded, but you will find other equipment from other manufacturers will not be compatible as they only allow for negative grounds. this limits your options in chosing equipment or manufacturers for the sunpower module system, but you're ok as long as xantrex continues to make equipment that accomodates the positive grounds and they have been around a long time too.
in general either system will work and though sunpower will take up less space the differences between them is small enough that in general it will take up close to the same amount of space. sunpower is more efficient and bp is more readily compatable with other equipment from other manufacturers. you will have to weigh everything as far as pros and cons, but the price of either system may also help make up your mind. ask to see installed systems they have put in and ask the owners questions on their systems and of the installer's workmanship.
i am in a situation myself that i'd need as much efficiency as possible and if given a system from either as a choice without factoring price or installer workmanship that i'd have a tough time chosing between these 2 choices. let us know what you go for.

I have Sunpower Panels. I didn't get them through contractor. Instead I got them through an installer in Cali that had them sitting around as left overs from a project with the utility and I got them at a great price. Space was not a concern for me but thier efficiency is amazing, even in low light. They also don't seem to lose as much power as I expected as the weather is warming up. The advantage of sunpower is thier high efficiency which means if you have limited space you can probably fit more panels on your roof in the same amount of space, and each of those panels will produce more power than the larger panels of other manufacturers with lower efficiency. The disadvantage, as previously mentioned, is the Positive Ground requirement. The positive ground requirment is instituted because of the all back contact A5 solar cells developed by sunpower. They use pos. ground inverters to eliminate a static polarization effect generated by the cell being at a different electrical potential from the ground. Positive grounding corrects this, eliminating the need for metal contacts on the visible surface of the cells, which in turn creates a larger solar absorbtion surface for the same amount of material, thus higher efficiency. Sunpower panels also perform very well in almost every catagory you can think of, low light, temperature coefficent... etc. Neil stated that Xantrex manufactures inverters for sunpower which is true. Thier current line of inverters are just Xantrex GTs with a sunpower brand label slapped on them and a slightly modified paint job. If you try to get a GT inverter directly from Xantrex though with the positive grounding option you will probably have a rather difficult time. I had to harrass them a little in thier forums before the ball really got rolling on them finding me an inverter, but they did and it works amazingly well, only took 2 weeks to show up too. However, sunpower would supply you with a xantrex inverter from thier stock. The issue you could have potentially is that 10 years down the road after your inverters warranty runs out and it breaks down, Xantrex may no longer manufacture Pos. Gnd inverters at that point and sunpower may go out of business. None of which are likely to all happen but its a small risk. HOWEVER, you could always buy a Sunny Boy inverter, every model they make are both positive or negative ground, you simply change a jumper fuse. The sunpower panels will also work with a negative ground inverter, they just lose about 25% of thier efficiency. If I were making your decision, and space was the primary concern I would go sunpower all the way.

I have a 5.5 kW sunpower system, my panels are Sunpower 205BLK's with a Xantrex/Sunpower inverter (Sunpower also offers the -m series inverter made by SMA/Sunnyboy as an alternative). I can second Iboc's comments, the panels seem to do pretty well in lower light conditions - but this being my only experience with a solar energy system my frame of reference is limited.

One other difference, which is subjective, is appearance. The Sunpower BLK modules are all black glass, not blue or blue gray with visible wiring stripes like all the others. This is a better aesthetic IMO, again this is highly subjective. My neighbor just installed a BP system and there is no comparison in appearance. The all-black Sunpower panels just look better as a retrofit compared to the blue/silver BP-supplied panels.

My panels are also a bit smaller than my neighbor's BP's (about 5 inches shorter, and 1.5 inches narrower - each - this difference adds up when you are installing several strings), and make more power per panel. The new Sunpower 210BLK panels are even better, being the same physical size yet with more output.

If the cost between BP and Sunpower is the same, I say go Sunpower. No question.

Just want to make clear that the Sunpower are fine panels for Grid Tied Inverters that support Positive Ground (an ordering option for Xantrex).

However, for Battery/Off Grid applications, most people run negative ground systems and Sunpower Panels do not operate well with negative ground installations (their power output drops by some ~50% (don't remember exactly).

And, as far as I know, there are no DC solar charge controllers that let you have a positive ground panel with a negative ground battery bank (not impossible--just not normally done).

The Sunpower panels themselves, if used in negative ground systems, will restore to full power (within an hour?) if properly reconnected as a positive ground system.

You can see a thread about this here:

http://www.solar-guppy.com/forum/viewto ... power#3258

-Bill

I have the SPR-215-BLK modules. Very nice looking. Also you can use them to charge batteries, I have heard of some people charging them using charge controllers. My question then would be, do you still see an efficiency loss even at low voltage. I think if you ran them at 40v (all parrallel) then there would be less polarization than if you ran them at voltages above 120v. I read that thier 17.5 volt 90watt battery charging panels work great using the same A5 cell technology. However there is a warning on the back that states "DO NOT WIRE IN SERIES". I think thats how they avoid polarization with the 90s, keeping the voltage low. However you can use them to charge batteries with a method that is alot more efficient and alot less risky. You could use the Sunny Boy inverters and a Sunny Island and use the Sunny Boy's output to charge the batteries. That way the only place you would lose efficiency compared to a 100% grid tied system is in charging the batteries when they need it. The rest of the energy is used in the home or sold to the grid with 90%+ efficiency, whatever the Sunnyboys are for efficiency.

If you look at the PDF link I posted earlier:

http://www.solarsales.com.au/download/p ... _paper.pdf

It does appear that if you have one or two panels in series, you will loose about 2-5% power--not that much.

At lower voltages (+100 volts), it appears that it will take a month of use to reach the maximum power fall-off point... It is unclear from the data that a 20 volt panel will see the drop-off 10-100 months later (log/log plotting of data)--or not at all...

-Bill