Sunpower system in San Diego - Good deal?

[KRenn]

For the effects of orientation try the Sharp estimator http://sharpusa.cleanpowerestimator.com/sharpusa.htm

It allows you to play around and see differences fairly easily.

I was going to say that PV Watts allows you to do the same as well.

http://gisatnrel.nrel.gov/PVWatts_Viewer/index.html

[russ]

For the effects of orientation try the Sharp estimator http://sharpusa.cleanpowerestimator.com/sharpusa.htm

It allows you to play around and see differences fairly easily.

[KRenn]

this is the kind of things I need to hear from real world people. So yes it is a good product, but only because of service and higher output per SQFT, is that the sum of it?

So yes, if I could only put 18 panels on my home, I would want to max them out.

So west facing panels are no good? I see them all the time though

Quality matters. I've never believed that solar panels are a commodity the way some installers treat them. I see SunPower as top-notch quality, if you're going to invest in something for 25 years, I think SunPower is probably the best choice as far as things go. For a long time the cool kids mantra was "a panel is a panel is a panel" but now with various manufacturers going bankrupt left and right, even with behemoth's like Suntech having issues, I'm all the more further behind a company like SunPower.


You get better efficiency panels which matter if you have limited roof space, better temperature coefficient than many comparable panels, a different doping process during production which does limit initial light-based degradation and a company that derived from actual scientists and researchers and not cute marketing guys. Yeah their sales pitch is a little BS-filled, but the product really does sell itself.

[bonaire]

Just so you guys know, I am a energy freak. In our previous home, I turned a 40+ year old home into an energy conserving freak. I put in a intellipro VR pool pump, invested in a breezeaire VR evaporative cooler, new windows, reflective/radiant barrier and more... Basically our 12 month average was about 500kW / month while the house never went above 75f even when it was 110 out and there was no point to get solar with what I did with that home but I don't think I can streamline this new home like I did with that one story 1800 sqft house.

I am already planning a whole house fan and other stuff to reduce the usage but there is only so much I can do with a 3500 sqft house

I've heard the "swamp coolers" are great for cooling. If you do get an EV, the best charge time would be midnight to 7am. That is enough time to fill a Leaf or a Volt. I have a volt and it is four hours to charge completely to give up to 45 miles in the warmer weather. Leafs have bigger batteries and can take 8 hrs at 240v or the new 2013 model can do it in about five and that gives about 70 total miles. Leaf leases are dirt cheap now in CA.

[centralCalsolar]

Just so you guys know, I am a energy freak. In our previous home, I turned a 40+ year old home into an energy conserving freak. I put in a intellipro VR pool pump, invested in a breezeaire VR evaporative cooler, new windows, reflective/radiant barrier and more... Basically our 12 month average was about 500kW / month while the house never went above 75f even when it was 110 out and there was no point to get solar with what I did with that home but I don't think I can streamline this new home like I did with that one story 1800 sqft house.

I am already planning a whole house fan and other stuff to reduce the usage but there is only so much I can do with a 3500 sqft house

[centralCalsolar]

It's not that simple especially for California where you have complex tiered electric rates that may make afternoon production more valuable than morning. As for Sunpower panels: the 20% more energy number appears to come from Sunpower documentation and relates to the slower performance degradation especially in year one:

see here

yes, both companies I have talked to in person so far set a client up on the E6 rate or "usage rate" meaning that it is more expensive in the date. There is the partial peak 10AM - 1PM which is like .30/kW and peak from 1-7 which is like .40c/kW and then back to partial till 9 but you also generate at those rates so if you were to say keep your AC off until you get home you would have generated a crap ton of power and got way ahead of yourself.... in theory.

I told them that I think it would be a good idea to get a electrical vehicle in the future when we are ready. We will be quite a few miles outside of town and I could see the benefit of using electric instead of gas in that case by sticking a few more panels on the roof to make energy for a car.

and charge the car past 9PM when it is .09c/kW

[russ]

You managed to find some real snake oil salesmen!

Quote, "With SunPower solar panels you can install more power in the same amount of space than with other panels, up to 50% more than conventional designs and up to four times more than thin-film solar. Our residential solar systems require significantly less roof space, so you can use fewer panels to produce the same amount of clean, renewable solar power."

Where the 50% comes from is pure blather - they are not comparing anything only making up numbers. SunPower is fine but the sales is seriously distorting reality.

[Ian S]

this is the kind of things I need to hear from real world people. So yes it is a good product, but only because of service and higher output per SQFT, is that the sum of it?

So yes, if I could only put 18 panels on my home, I would want to max them out.

So west facing panels are no good? I see them all the time though

It's not that simple especially for California where you have complex tiered electric rates that may make afternoon production more valuable than morning. As for Sunpower panels: the 20% more energy number appears to come from Sunpower documentation and relates to the slower performance degradation especially in year one:

High year one performance delivers 7-9% more energy per rated watt. This advantage increases over time, producing 20% more energy over the first 25 years to meet your needs.

see here

[centralCalsolar]

Marketing guys are entertaining people! Did they tel you if you can actually measure the difference in output due to this divine technology? Can you actually see the difference over a years time? Will it ever pay back?

You might buy SunPower because they are first class but disregard the BS sales talk.

this is the kind of things I need to hear from real world people. So yes it is a good product, but only because of service and higher output per SQFT, is that the sum of it?

So yes, if I could only put 18 panels on my home, I would want to max them out.

So west facing panels are no good? I see them all the time though

[russ]

"The SunPower premium monocrystalline cell substrate enables the cell to be very sensitive to very low levels of light. The panels “wake up” the inverter earlier in the morning and continue to generate energy later in the day than other technologies."

Marketing guys are entertaining people! Did they tel you if you can actually measure the difference in output due to this divine technology? Can you actually see the difference over a years time? Will it ever pay back?

You might buy SunPower because they are first class but disregard the BS sales talk.

[bonaire]

With all the roof angles, you may have to decide to use lesser panels and micro inverters or multiple string inverters, which increase the system price somewhat. You just need to think through the "do I really need solar?" question.

What if the power company comes to their senses and fixes the tiered rate structures? Could you be satisfied with the one largest roof array and then add more later? Are you fully able to take the tax credit? There are times when scaling back a little bit saves you in the end. Perhaps you can only get a certain sized loan or have only so much cash to spend.

My power one inverters are woken up before the sunrise and show a few watts down to sundown. I think we're talking a few watts here or there. The primary power generated by any solar array is 10am to 2pm. West and east facing probably are a waste. What is best would be 18 high efficiency modules, one good string inverter and a bit of conservation and power analysis of your usage. Which, as you say, you don't know what it will be as you haven't moved in.

Of course the federal tax credit will still pay you even if you installed the modules in your basement. Don't put up a poor performing e or w facing subsystem if it isn't going to produce well.

[centralCalsolar]

The higher efficiency module doesn't take in more hours of sun. The total produced from a higher efficiency module is higher than a lesser module. You are paying for more power per square foot. No other magic involved. A 6kw sunpower system may need 18 modules while a SolarWorld 6kw system using 260w modules would need 23 or 24. More roof space, more racking, wiring, etc. if you are short on space, sunpower is it. Most critical thing is if you have any tree shading to work around.

You can do the math on a different module system and see if paying less for a system up front is better for your financial situation, such as ability to take the tax credit. If you are just trying to get off of higher tier rates in CA, a combination of conservation, solar, and other financial decisions can be put together and not break the bank with the largest sunpower system that will fit.

thanks for the info, this link kinda talks about the same stuff I heard today in how sunpower panels produce more by taking in light earlier in they way they refract the light, being able to take in power from the whole module even when a small portion is covered by say a leaf or shade

http://www.solarenergyalliance.com/Sunpower.html

I have space for 18 facing south, probably another 8 facing west and 10-12 facing east so I could go with another panel and still get 8kW or more but I just thought a sunpower system say like 7kW would produce the same amount as say a 8.5kW system in a given period of time, like per month/year etc... but if that is not the case, that changes a lot of things.

So what is the above site saying when they say:

"The SunPower premium monocrystalline cell substrate enables the cell to be very sensitive to very low levels of light. The panels “wake up” the inverter earlier in the morning and continue to generate energy later in the day than other technologies."


Also, our house is new construction, still being built and there are no trees currently and nothing that will block any light for quite some time. it is also a 2 story, so I can't see a lot of stuff getting on the panels other than some bird poop or something.

[bonaire]

The higher efficiency module doesn't take in more hours of sun. The total produced from a higher efficiency module is higher than a lesser module. You are paying for more power per square foot. No other magic involved. A 6kw sunpower system may need 18 modules while a SolarWorld 6kw system using 260w modules would need 23 or 24. More roof space, more racking, wiring, etc. if you are short on space, sunpower is it. Most critical thing is if you have any tree shading to work around.

You can do the math on a different module system and see if paying less for a system up front is better for your financial situation, such as ability to take the tax credit. If you are just trying to get off of higher tier rates in CA, a combination of conservation, solar, and other financial decisions can be put together and not break the bank with the largest sunpower system that will fit.

[centralCalsolar]

I had a meeting with another solar installer today that pushes sunpower. He had a pretty convincing argument for the extra cost of sunpower.

He was saying that on average they have more hours in the day that they take in sun. For example if a traditional panel had 5 hours in this area, the sunpower panel would be taking in 6.5 hours positioned in the same spot.

Is there any truth to this?

He quoted a 5.3kw (AC) system that generated 25.7 kW /day. well by that math, that is only 4.84 hours. He said that they undershoot the performance because they have to guarantee that it will perform what they say it will but still those numbers are quite a bit off.

So any users or installers with experience in this thought?

Does a sunpower panel produce ~20% more kW for the same Watt? Meaning comparing 2 6kW system, 1 a sunpower E20 panel system and a generic 6kW system. Would the sunpower 6kW system produce more kWs even though they are rated at the same wattage? This is ignoring panel counts, I am strictly talking watts vs watts

[centralCalsolar]

So what is a good source to use to find contractors/installers for a wide eclectic mix of PV manufacturers then? Meaning not just sunpower, topsun, t-solar, solarbine etc.... but as you said, there could be better $/watt out there given a lower efficiency of the PV panel.