what the best time in the year it good negociate price for Solar pannel

I would agree with Dev, the first thing that jumped out at me was 299 degree orientation. Is there some racking system that can orient those panels towards the south? Be interesting to see suneye pics for this, even PV watts estimate would be good.

*When I change my (29 panel)array's PV Watts orientation from 193 degree to 299(23deg tilt), my estimated wattage drops from 8k to 5.5k..that's a pretty significant hit, and would lengthen your payback considerably..

 

The problem is that due to the orientation of your roof, and the fact that solar installers like to install panels using the same slope of the roof, your panels will be facing in a direction that is NW (299 degrees), as opposed to the panels on the other side of the roof that face SE (119 degrees). It's possible that that the installers could tilt the panels the other direction (facing SE), but then you run into shading issues, and it doesn't look nearly as neat and clean from the street. If you have an HOA, they could object.

 

That's about $4 a watt installed, which isn't too bad. However, if they insist on pointing them at a 299 degree azimuth (NW facing direction), then I would decline. You are going to lose a lot of production, especially in the winter months.
Do you know if they took into account the federal tax credit?

Rather than focusing on a price on the panels, you should be really be asking how much extra power will the system produce, especially if pointed in a NW direction.

 

Here's a nifty utility that will show you the angle of the sun at various times at a specific location. You can even set it to show specific times of the year.

SunCalc - sun position, sunlight phases, sunrise, sunset, dusk and dawn times calculator

I have it set for San Diego for right now.

Here's what the winter solstice will look like:

SunCalc - sun position, sunlight phases, sunrise, sunset, dusk and dawn times calculator

As you can see, if the panels are aimed at 299 degrees, they aren't gonna get much sun.

 

You can even input your specific address and zoom in to see exactly how the sun will hit your roof. You need to select satellite mode, and disable the 45-degree view to get the best view.

 

Here's your address: SunCalc - sun position, sunlight phases, sunrise, sunset, dusk and dawn times calculator
In the upper right hand corner are two buttons labeled "Map" and "Satellite". Click on Satellite. It should change to satellite view. If you then put your mouse over the satellite button and move down so that it's between the satellite button and the chart of times, you can click in that space and it will disable the 45 degree angle view, so you get a true birds eye view of your property.

 

Note that the date is set to December 21st. There's a "Now" button to take you to, well, now.

 

wow, that's awesome. and if you look at street view, you can see the OP's blue prius in the driveway!
I understand that the OP wants another system so contractors are giving the customer what he wants, but why isn't any contractor telling him NOT to install panels facing north? You have a sun-room on the back of the house, and a garage...why not create a system on either of those surfaces? Actually, I'd investigate mounting the a racking system on the side of the house as this faces almost due south His Enlighten profile is incorrect as it shows his array at 180degrees, when it's the opposite of 299...150degrees.

 

I think it's bad. I don't see the value in it. what's the degree of roof pitch on your existing system(look in your pvwatts estimate in Enlighten). It looks like you have room for panels on the lower roof section, the sun-room and/or that free standing shelter in the back yard. seems to me like any of these would be better than than your north facing roof.
"PVWATTS v.2: AC Energy and Cost Savings"

"Station Identification"
"Cell ID:","0174365"
"State:","California"
"Lat (deg N):", 32.73
"Long (deg W):", -117.17
"PV System Specifications"
"DC Rating:"," 2.9 kW"
"DC to AC Derate Factor:"," 0.770"
"AC Rating:"," 2.2 kW"
"Array Type: Fixed Tilt"
"Array Tilt:"," 32.7"
"Array Azimuth:","299.0"

"Energy Specifications"
"Cost of Electricity:","17.3 cents/kWh"

"Results"
"Month", "Solar Radiation (kWh/m^2/day)", "AC Energy (kWh)", "Energy Value ($)"
1, 2.13, 120, 20.75
2, 2.87, 157, 27.14
3, 4.02, 257, 44.43
4, 5.23, 324, 56.01
5, 6.06, 388, 67.08
6, 6.08, 374, 64.66
7, 6.29, 394, 68.11
8, 5.71, 356, 61.55
9, 4.65, 277, 47.89
10, 3.40, 207, 35.79
11, 2.36, 131, 22.65
12, 1.90, 102, 17.63
"Year", 4.23, 3088, 533.85


at $533 a year, it's going to take you quite a few years to realize a return on your $9k out of pocket. and that's year one, your panels will be much less efficient at year 15. If you have $14k to invest, invest it in an IRA, your tax deferred return will be MUCH higher in 15yrs when your solar array will just be reaching break even.

 

My opinion:

The existing system is already installed on the most cost effective roof space. Even then, you can see that 2 panels are shaded by the chimney around 2pm right now. Not bad, though - over the lifetime of the system those panels are down about 10% from the other panels.

One thing to keep in mind - the current system 4.5kW is significantly outperforming PVwatts by generating over 7 MWh/year. Assuming a roof pitch of 20*, you have to adjust the derate factor to 89% to get close to 7 MWh/year. With my system, I find so far that I can assume a 85% degrate factor. Enphase systems seem to significantly outperform PVwatts for at least the first 5 years or so, anyway.

Let's also assume that we can fit about 3kW on the north-west (300*) facing roof for calculations. We'll use a more conservative 85% derate factor and assume 20* roof pitch. PVwatts says this will generate about 4 MWh/year.

On PVwatts when you run the NW vs SE with 20* and 85% derate - the difference in performance of the 2 isn't that much different - 1480 kWh/year vs 1320 kWh/year - or about 10% less energy per year.

This is much better than the calcs others have run above and very reasonable, IMO. Even at a 20% overall efficiency hit, you are doing better than much of the country in terms of output per watt with an optimal install! Certainly way better than Germany - the leader in PV installation.

Looking at it from a financial perspective - you should aim to get your post-incentive price to at least 10% less than what you paid for your original system per watt. If you paid $22k - 30% tax credit = $15.4k or $3.42/W for your current system, I'd aim to get the price of your new system down to $3.08/W or less.

So if we take your earlier quote of 12x245W = 2.94kW = $13k - 30% tax credit = $9.1k which is $3.095/W.

Very close to the target price - so IMO if you are comfortable with the installer - go for it. If you can get the price at least $200 lower even better. Sounds like you really want it and IMO the price is right.

Note that none of these calculations take into account the tiered rate schedule most of us are on - this makes the first system more cost effective since it is offsetting more expensive ~28c/kWh electricity instead of ~14c/kWh electricity. If you don't use AC or other heavy loads during the day, with the addition of your new west-facing system you should definitely consider going with the TOU schedule which could prove to be very enticing.

BTW - I absolutely would not consider either the sun-room or small roof on the north addition of the house.

The sun-room has very little usable area - shading will be a big issue in the afternoon for much of the structure - and the tall hedges are likely to be an issue in the winter. It also is not likely to be able to hold solar panels without significant engineering retrofits.

The north-room will also have very significant shade issues in the winter.

In contrast, the NW facing roof is obstruction free and only presents at 10% reduction in efficiency from your existing system and 20% from an optimal south facing roof.

Hope this helps!

PS - there's at least one San Diego installer on the Enphase Community if you are looking for a competitive quote.