Confused on Solar Panel System Design

[biglips31]

Considering a system for my home in california.

Received a quote from Local Company that spec'd out a 7.3kw system.

I contacted another local company that spec'd a 3.43kw system because
they said a 7kw system will not fit. I attached a photo to show the way
they spec'd it out.

I need more KW because the 3.43 system is only getting 28% of my needs.
What is bothering me here is that the company is stating code is that panels
can not be 36" on my roof ridge which is causing the system to be downsized.
I have never heard of this. Can anyone confirm?

Thanks!
solarpanels.jpg

[bonaire]

Is North straight up on the picture?

Does their spec include micro-inverters due to all the roof angles? that would be best. Are there 14 modules shown here or does the back room there have more modules?

You can go with 72 cell modules and PowerOne micro-inverters (which support them). Those modules are slightly bigger and would help with space efficiency. Two-high of 72-cell modules would be pretty good if scattered around like that. PowerOne micro-inverters support 250W and 300W output choices. Much better than Enphase 215W microinverters in such a situation. I know that most installers are familiar with 60-cell modules as "standard" but it's not much different to upsize to 72-cell like say the Suniva OPT 72-cell module which is 310W of max power. You can also "upscale" to say a Sanyo or SunPower module for higher efficiency too. You may also want to "Buy-USA" and choose from what's made here such as SolarWorld and Suniva.

Is price an option (like it has to be below say $5/Watt)? If not, you have lots of options and don't stop shopping installers until you are very happy.

[biglips31]

PV Guidelines.

I found a 18 page forest draft PV install guideline. I'm not sure if this pertains
to me but this totally debunks what the installer was telling me.

2.1.1 Access/Pathways

a. Residential Buildings with hip roof layouts: Modules should be located in a manner that provides one (1) three-foot (3') wide clear access pathway from the eave to the ridge on each roof slope where modules are located. The access pathway should be located at a structurally strong location on the building (such as a bearing wall).

b. Residential Buildings with a single ridge: Modules should be located in a manner that provides two (2) three-foot (3') wide access pathways from the eave to the ridge on each roof slope where modules are located.

c. Hips and Valleys: Modules should be located no closer than one and one half (1.5) feet to a hip or a valley if modules are to be placed on both sides of a hip or valley. If the modules are to be located on only one side of a hip or valley that is of equal length then the modules may be placed directly adjacent to the hip or valley.

You can see from my roof line picture that 2.1.1 c pertains to my home. In no areas are panels on both sides of hip or valley. I think I could put panels all the way from hip to the valley and from the ridge to the gutter.

I must be missing something... I may need to call the city I suppose.

[biglips31]

Is North straight up on the picture?

Does their spec include micro-inverters due to all the roof angles? that would be best. Are there 14 modules shown here or does the back room there have more modules?

You can go with 72 cell modules and PowerOne micro-inverters (which support them). Those modules are slightly bigger and would help with space efficiency. Two-high of 72-cell modules would be pretty good if scattered around like that. PowerOne micro-inverters support 250W and 300W output choices. Much better than Enphase 215W microinverters in such a situation.

Yes, north is straight up..

I have received two quotes/designs so far.

1st System 3.43kw System - Shown in picture - Specs Below

System Size (STC-DC): 3.43 kW
System Size (CEC-AC): 2.95 kW
First year production: 4,883 kWh*
Solar Panels:
8 modules: ET Solar Industry ET-P660245BB
6 modules: ET Solar Industry ET-P660245BB
Inverter: Power-One PVI-3.0-OUTD-S-US (240 V)

2nd System 7.35

Right (SE) 12 Panels
Front (SW) 11 Panels
Back (NE) 7 Panels

Solar Panels: 30 - REC 245BLK
Invertor - 30 - Enphase M215-60-2LL-S22 240V

[inetdog]

I found a 18 page forest draft PV install guideline. I'm not sure if this pertains
to me but this totally debunks what the installer was telling me.

2.1.1 Access/Pathways

You can see from my roof line picture that 2.1.1 c pertains to my home. In no areas are panels on both sides of hip or valley. I think I could put panels all the way from hip to the valley and from the ridge to the gutter.

I must be missing something... I may need to call the city I suppose.

The way I read it, section a) will still apply to some parts of your installation too. What I see is that c) adds some additional information about how close to hips or valleys the panels can be installed, but does not remove the requirement for the 3 foot wide vertical corridor, even though it allows some part of that corridor to be located on the other side of a hip or valley that runs from the eaves toward the peak.

...one (1) three-foot (3') wide clear access pathway from the eave to the ridge on each roof slope where modules are located.

But you are correct that this does not show any restriction on how close to the central ridge the panels can be installed.

[bonaire]

The nice thing about the PowerOne Aurora is it has two MPPT inverters within so it can handle two distinct strings of modules that they have pointing in different directions.

Do ask these guys to check into the 72-cell modules as they may allow higher output while doing very similar jobs and price should be better on a dollar-per-watt basis. The two module choices made (ET and REC) are "ok" quality but not the best. I think you may want to keep shopping once you find out what the city ordinances are and the reality of where you can put the panels.

There are a lot of installations in Australia like this where they have flatter roofs with more eves like yours. They usually do maybe 6-8 modules total as it was part of some government incentive program.

If you do go with 72-cell modules, that will be too large for Enphase inverters (which are becoming "darlings" of high volume installers - must be getting them cheap). ET also offers a 72-cell module if the installer would be comfortable with that vendor. So you can still use dual-MPPT inverters like the PowerOne (just size it up to 3.6 or 4.2 if you go to larger modules). My home system has two arrays of 16 modules each using one Aurora 3.6 each. Good inverter.

Helpful: http://sroeco.com/solar/most-efficient-solar-panels

Notice REC and ET are known as "Tier-4" modules.

[Naptown]

So they are requiring 3 feet at the ridge and 3 feet along each edge and 3 feet split on the valleys.
This sounds like the 2011 firecode that may have been adopted in your jurisdiction. We have the same problems in some jurisdictions here that have adopted that same code.
It sucks but we have to live with it although the industry is fighting it somewhat. (Kind of hard to say no to first responders)
Check with your local building department to see if this is true. they will be tho only ones to tell you that have any authority.

[SoCalsolar]

It does vary from city to city but generally....

It does vary from city to city but generally it is 3' from the ridge and 18" in the valleys some cities allow you to get a variance or allow you to build right to and over the ridge, Rancho Cucamonga and Murrieta are two I can think of that will allow you to go right to the ridge. Most others have adopted the 3' and 18" rule. If an installer can put more on they will it is usually in their interest to do a larger job rather than a smaller job. Stay away from NE orientation unless you reverse tilt the panels. Is this in SoCal? looks a bit like a Mira Loma neighborhood I'm familiar with. The smaller system is conservatively designed looks as though you could get a few more modules maybe even 6 or 7 more. If you use SunPower or another high efficiency panel you can get a larger system maybe 6.5kw DC or so maybe cover 60%-70% of your bill.