One last look before we sign for Sunpower system

[Ionizer]

Sun Power Monitoring is on. App is working, but Sunpower needs to change it's demo app. Not sure why it shows consumption and production on the demo, yet only shows production on the real app.

Looks like I'm averaging production about 48kWh per a day. If only it could stay that way id be at 17,520 kWh for a YEAR! MY QUESTION: I noticed that the panel production have not gone over 6,200 watts at the peak of the day on a 8,040 watts system. Is this normal? Thought they might have got closer to the full wattage during peak time.

I might be able to live with it. We have already banked a little over 150kWh!

[Naptown]

The answer lies in day of year location azimuth of array, shading and tilt of array.
It may be normal It may not

[flinstone]

Sun Power Monitoring is on. App is working, but Sunpower needs to change it's demo app. Not sure why it shows consumption and production on the demo, yet only shows production on the real app.

Looks like I'm averaging production about 48kWh per a day. If only it could stay that way id be at 17,520 kWh for a YEAR! MY QUESTION: I noticed that the panel production have not gone over 6,200 watts at the peak of the day on a 8,040 watts system. Is this normal? Thought they might have got closer to the full wattage during peak time.

I might be able to live with it. We have already banked a little over 150kWh!

I strongly recommend anyone who owns or plans to own a system to plot their expected power-production graphs. Then you can see if your system is performing as expected, if panels are getting dirty, or if there's a defect. You can use the PVWatts calculator to input your system size, geographic location, and roof angles and then export the monthly and hourly numbers to your computer and then import them into your favorite spreadsheet (Google Docs has a free web-based spreadsheet). You use the spreadsheet to generate charts that can tell you what to expect at different times of day and times of year under historical weather conditions.

I've attached a couple of examples charts I generated when I was considering which roof face to put my panels on. I have suboptimal SouthEast and NorthWest facing roofs.

One thing about PVWatts is that it defaults to a conservative derate factor of 0.77. You can use the California Solar Initiative Rebate tool to plug in your exact inverter model and panel model to figure out the derate specific to your equipment. Simply divide the unadjusted AC Rating by DC Rating in the CSI report. It should come out to somewhere around 0.85 to 0.90. You plug this value into the derate field in PVWatts to get a more realistic production numbers.

[Naptown]

One caveat
PV watts is based on 20 years average weather.
If you read the disclaimer the predicted output can vary by up to 20%

[inetdog]

One caveat
PV watts is based on 20 years average weather.
If you read the disclaimer the predicted output can vary by up to 20%

And that is not even taking into account global weirding.

[bando]

Are there any companies out there that can supply SunPower panels before the end of the year? We'd hate to install one in January and have to wait a full year to take the credit.

Also, are the E series panels "outdated" now and not preferable to the X series? The quote we received for Sunpower panels is for the E20. Not sure if we should insist on X

[Naptown]

The e-20 is one percent less efficient
The x panels are back ordered for 24 weeks
Not much difference between the 327 and the 335 or 345
the x panels are also a
Bit more expensive and have a black back sheet so you don't see the diamonds and cell spacing.
I don't know why the discontinued the black back on the E20

[bando]

also, we have some quotes from a local vendor in San Diego and have seen the following:

48 Kyocera panels come out to about $600/panel
36 Sunpower panels come out to about $1025/panel

same output, same bill offset projections


does that seem about right to you? that Sunpower panels (all else being equal) cost 70% more than other panels ?!?!? i knew it would be MORE however i thought the fact that you'd need less # of panels and less roof space was worth maybe a 25-30% premium. but 70% premium for the brand name just seems astronomical

[bando]

The e-20 is one percent less efficient
The x panels are back ordered for 24 weeks
Not much difference between the 327 and the 335 or 345
the x panels are also a
Bit more expensive and have a black back sheet so you don't see the diamonds and cell spacing.
I don't know why the discontinued the black back on the E20

thanks. are the E20's backordered too? i suppose sunpower in general is too expensive to store on hand.

[Naptown]

Don't compare a per panel price
Compare the $ per watt DC
It would be unfair to compare a 327 watt panel with say a 250 watt panel on the gross panel price. They are two different things
$ per watt is the only fair comparison
So taking that into account
48x 600 = $28800
36 x 1025 = $36900 or 3.13 a watt
A very good price for sunpower
Do the math on the other one

The others are according to your post 245 watt
You buy sat by the watt not panel

[frizzlefry]

thanks. are the E20's backordered too? i suppose sunpower in general is too expensive to store on hand.

When we tried to switch a month ago to E series panels we were told would come in at the same time we were expecting the X series. [edited for clarification]

[Naptown]

When we tried to switch a month ago to E series panels we were told similar lead times as X series.

Was that a Sunpower lease or a purchase through a dealer

327 white last update were 3 weeks on purchase ( as of 9/25)

[frizzlefry]

Was that a Sunpower lease or a purchase through a dealer

327 white last update were 3 weeks on purchase ( as of 9/25)

It was purchase. Sorry what I wrote was a bit off. Lead time would have been the same time we were expecting X panels which would be October. So about 4-5wks at the time I had asked.

[Ian S]

Don't compare a per panel price
Compare the $ per watt DC
It would be unfair to compare a 327 watt panel with say a 250 watt panel on the gross panel price. They are two different things
$ per watt is the only fair comparison
So taking that into account
48x 600 = $28800
36 x 1025 = $36900 or 3.13 a watt
A very good price for sunpower
Do the math on the other one

The others are according to your post 245 watt
You buy sat by the watt not panel

Sounds to me like Sunpower has found the way to avoid being lumped in with other panels as a "commodity" item. Not so long ago, some folks were claiming they'd go bankrupt. Now they can't satisfy demand and their stock is soaring to a two-year high!

[bando]

Don't compare a per panel price
Compare the $ per watt DC
It would be unfair to compare a 327 watt panel with say a 250 watt panel on the gross panel price. They are two different things
$ per watt is the only fair comparison
So taking that into account
48x 600 = $28800
36 x 1025 = $36900 or 3.13 a watt
A very good price for sunpower
Do the math on the other one

The others are according to your post 245 watt
You buy sat by the watt not panel

sorry, i thought i mentioned that it's similar production and offset, so is that not like comparing apples to apples? i'm just trying to get a sense for "how much" of a premium you are paying for the Sunpower name.

(1) Sunpower 36 panel system - 10,416 W AC (CEC-Rated) - $38,260 would bring it to $3.67 per W AC

(2) Kyocera 48 panel system - 10,306 W AC (CEC-Rated) - $28,740 would bring it to $2.78 per W AC


So that would be approximately 32% price premium per Watt just for the Sunpower E20's over a "regular " panel like the Kyocera KD245GX. Is that a fair estimate? Or can be negotiate the Sunpower down to more like a 20% premium?

We have plenty of room for the 48 Kyocera panels however it would span two areas of the house. With the fewer Sunpower panels, we can get all 36 in a perfect rectangle over just one area which is preferable to us aesthetically.

The other problem is the availability of Sunpower puts us into 2014 and we don't know if that's worth it if we can just get something in by 12/31/13 and make the most out of the federal tax credit.

What do you think?