Greetings from cloudy Frederick, MD

[websterize]

Since our install this past Thursday, we've had nothing but clouds and rain. Like gloomy wedding weather, I consider this a good omen. Here's to a bountiful 2012 solar harvest -- very amped to join the PV club.

[Naptown]

Your numbers are not adding up module to gross wattage
I assume these are 260W modules and 40 of them?
What drove the decision to use 3 SB3000 inverters? Just curious why instead of say a fronius 10uni
Were all the modules on one roof plane or multiple pitches and azimuth? That may be the reason for above.
Didn't your installer tell that putting up PV is the same as washing a whole parking lot full of cars. It is guaranteed to rain

[websterize]

Pardon any dense answers/questions by me -- ye olde PV math is still a little foggy. Grateful for feedback/corrections.

>Your numbers are not adding up module to gross wattage

The system is made up of 40 x 260W panels, which is 10.4 kW, correct? Is this what you mean by gross wattage?

From our SMA system profile page:
System power: 9.48 kWp
Annual Production: approx. 10,874 kWh (1,147 kWh/kWp)
CO2 avoided: Approx. 10.3 tons per annum
Modules: Sch

[Naptown]

Did they add another meter to measure the solar output generated?

[Naptown]

Just a couple of more thoughts
Your system should not be turned on until the meter has been changed for a net meter.
There are many meters out there that will appear to run backwards but are actually counting up. This is because the meter is reading the revolutions on the wheel. Which way it is turning doesn't matter. The counter always goes up.

You have 40 modules on the roof. I am curious how he configured the strings for three inverters. I can't seem to make 40 divide equally by 3.

A more robust system. Probably not. But there are 2 more inverters that will need to be replaced around year 12 or 13.

I hope your installer did not come back to you with a change order increasing the contract price. Three 3000W inverters will cost more than a single 10,000 watt. And the change was not generated by your increasing the system size. They should have absorbed the additional cost. If they did great if not you didn't get so great a deal.

[websterize]

Thanks much, Rich. No increase in price. The installer, AtisSun, absorbed the cost of the 3 x 3000. I did not think about the additional replacement cost in 10+ years. Still don't understand how the unexpected arrival of 260W panels instead of 255W (a 10.4 kW array instead of a 10.2 kW array) would cause the SMA software to recommend 3 x 3000 inverters vs. 1 x 8000.

I'm also not sure how he strung the array, but the project manager said they divided it vertically, so as you face the front of the house, there's a left, middle and right section:

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Appreciate your wisdom. All the best.

[websterize]

Did they add another meter to measure the solar output generated?

Not yet. Install needs to pass electrical. Delivery of the net meter from FirstEnergy-Allegheny Energy is hopefully a few weeks away. Meantime, the array is online.

[Naptown]

Thanks much, Rich. No increase in price. The installer, AtisSun, absorbed the cost of the 3 x 3000. I did not think about the additional replacement cost in 10+ years. Still don't understand how the unexpected arrival of 260W panels instead of 255W (a 10.4 kW array instead of a 10.2 kW array) would cause the SMA software to recommend 3 x 3000 inverters vs. 1 x 8000.

I'm also not sure how he strung the array, but the project manager said they divided it vertically, so as you face the front of the house, there's a left, middle and right section:

| | |

Appreciate your wisdom. All the best.

The questions I had have been answered.
AtisSun is an installer that touts being exclusively a Hot water installer. Seems that has changed.
I suspect that you are the guinea pig for PV or very close to it.
The reason I asked about a separate meter (not the net meter that Allegheny will install) is that it is required in Maryland for systems over 10KW DC in order to get your SREC's.
The inverter thing has me puzzled but I don't have time right now to run string calculations for that configuration or come up with a reasonable configuration.

I just ran string calculations for those inverters and could not come up with a recommended string configuration for 40 modules. The closest I could come was for 39 modules. This means that there is one module on the roof which is either not connected or there is one string that has an extra module
At 14 modules on the string the inverter is overloaded and the voltage is in frying the inverter territory on a very cold day ( I use -20C for coldest temperatures.) Overvoltage on an inverter is not covered under the warranty.

[Naptown]

Not yet. Install needs to pass electrical. Delivery of the net meter from FirstEnergy-Allegheny Energy is hopefully a few weeks away. Meantime, the array is online.

The array should NOT be online prior to inspection and installation of net meter.
If you are going to have it online I seriously suggest turning off everything in the house. Turn the array on and verify that the meter is indeed counting down. This may take 20-30 minutes depending on how much the system is producing.
Again some meters will appear to be spinning backward but are actually counting up.

[CJ SolarTown]

Thanks much, Rich. No increase in price. The installer, AtisSun, absorbed the cost of the 3 x 3000. I did not think about the additional replacement cost in 10+ years. Still don't understand how the unexpected arrival of 260W panels instead of 255W (a 10.4 kW array instead of a 10.2 kW array) would cause the SMA software to recommend 3 x 3000 inverters vs. 1 x 8000.

I'm also not sure how he strung the array, but the project manager said they divided it vertically, so as you face the front of the house, there's a left, middle and right section:

| | |

Appreciate your wisdom. All the best.

Good to hear the installer didn't add the extra cost. Hard to say whether a standalone 10 kW or 3 separate array system better because each will have their pros and cons. I like the isolation affect with 3 separate solar systems especially when the cost similar. Excellent setup

[Naptown]

Good to hear the installer didn't add the extra cost. Hard to say whether a standalone 10 kW or 3 separate array system better because each will have their pros and cons. I like the isolation affect with 3 separate solar systems especially when the cost similar. Excellent setup

In his instance there is no way to configure 40 of those modules on those three inverters.
Either one module is diconnected or he runs the risk of overvoltage on one of the inverters.
I ran that every which way I could think of and could not come up with a solution that worked.
Try for yourself The sunny design tool is free and online. you will need version 2.2 as those modules don't show up in Ver2.1

So not so excellent a set up IMHO

[Naptown]

Websterize
Have you asked your installer for more information about what he is installing?

[websterize]

Yes, more to come. Thanks again.

[websterize]

AtisSun stands behind the array configuration: "Every system we install is not only highly scrutinized by us for proper design, but also by our manufacturer's team of engineers who are responsible for accurately designing thousands of PV systems worldwide."

At each step of the process so far, they have exceeded my expectations. We'll see how it goes.

Thanks again for the feedback.

[Naptown]

AtisSun stands behind the array configuration: "Every system we install is not only highly scrutinized by us for proper design, but also by our manufacturer's team of engineers who are responsible for accurately designing thousands of PV systems worldwide."

At each step of the process so far, they have exceeded my expectations. We'll see how it goes.

Thanks again for the feedback.

that's what they told you. Have they provided any documentation from Schuco or SMA on the equipment?
Ask them to give you the string calculations, The array configuration how many modules on each inverter and how is each set up. You are the customer you have a right to the information.