Hello from sunny San Diego!

[Cartwright]

I have decided to make the move to solar and am trying to get it done before SDG&E NEM rules change.

I am in San Diego (92117) and have a flat, torch down asphalt roof. My roof is shade free.

My current usage is around 665kWh/month. That is for 2015, we were very conservative with our A/C. The house is fairly new and very well insulated, efficient windows and appliances. The main conservation move we can still make is to change a bunch of halogen bulbs to LED, but that'll get phased in over time.

We want to feel more comfortable running the A/C and I am also considering an EV (Tesla) in the next year or so.

With that said, I'm gathering quotes and will post some quote details on here once I have everything organized. I know that people mostly compare $/W and I am curious if that is usually stated before or after the federal tax credit? The quotes I have so far range from $4.40-$5/W before the tax credit, which is significantly higher than I generally see posted here. I assume it is DC watts used.

Also, how much of a premium should I expect if I want a ballasted mount to avoid puncturing the roof?

Thanks in advance for any replies, I've found this forum to be extremely helpful already.

[DanKegel]

Good questions!

I think the $/W quotes are usually without subsidies (and then people also post the subsidized $/W, identified as such, for clarity). And I think they're for "faceplate DC" watts, so they don't take inverter efficiency or illumination into account.

BTW if you are going to be doing a tilt mount on a flat roof, it'd be interesting to hear if you get any quotes for bifacial panels like the GxB310; it's possible that they'd get enough light on the back side to be worth it, especially if you point them west or southwest instead of south. (I'm experimenting with them myself, no results yet.) Though if you have plenty of space, there's no way it'd be worth it, judging by panel prices at http://www.civicsolar.com ...

We had solar installed on a fairly new similar flat roof eight years ago, with penetrations, with no problems since then. Glad we reroofed before doing it, though, the old roof was a nightmare.

[GFS]

Hi Cartwright,
I am also in the San Diego area (92116) and am looking to go solar by this summer but with a DIY system. Since we're both in SDG&E land, you may have seen their new proposal to shift "Peak pricing" times from there current daytime times to 4-9 PM. I'd recommend looking at putting in an inverter that has the option of being battery backedup for future expansion. The Tesla Power Wall is one example of this. It can connect to a SolarEdge 7600 inverter (which is what I'm planning on using) for load shifting (or so they claim). I think that the Power Wall is too expensive at this time but prices should come down in the future and having that possible option built in to your solar system right now might be very helpful down the line. Just my 2c.

Gordon

[Cartwright]

GFS,

Yep, I've already made Power Wall compatibility a requirement for my system. Some of the installers have balked at that, but it is something I definitely want for future proofing.

Did you get any installer quotes for reference? I'm curious what type of pricing is considered normal for the area because the numbers I'm seeing seem high relative to what others have posted. I don't know if there is a time-of-year/demand effect happening or I'm just getting gouged.

[jflorey2]

Hi - I am also in San Diego and had a few notes.

First off, in the Claremont area you are going to have issues with June gloom. That tends to push the ideal orientation to about 15 degrees west of true south. Since you have more freedom with orientation than most that may give you a few more kwhr a month.

Consider EV-TOU to deal with the EV. It can save money whether or not you use solar.

Ordinarily I recommend SMA inverters with the "secure power" feature for blackouts, but since we don't really get them here, not as big a deal.

[Cartwright]

jflorey,

Thanks for that input. I have been leaning toward SMA as a brand, but it looks like they just announced their Power Wall compatible version, so I doubt it will be available in time for my system.

Interesting point about direction, I will make sure that is taken into account.

[GFS]

jflorey,

Thanks for that input. I have been leaning toward SMA as a brand, but it looks like they just announced their Power Wall compatible version, so I doubt it will be available in time for my system.

Hi Cartwright,
You may want to check and see if any of SMA's regular inverters (I.E. the ones you can buy right now) will be upgradeable in the future to the Power Wall compatible version. The nice thing about the SolarEdge 7600 is that the regular 7600 will be upgradeable to the StorEdge Inverter which can take the Power Wall. Just an idea.

Gordon

[Cartwright]

Am I correct in assuming that for Power Wall compatibility it is better to do a string inverter over microinverters?

[J.P.M.]

Cartwright:

- Download and read " Solar Power Your Home for Dummies", a free online download.
- The going rate around here is ~ $3.50/Watt unless something special is required (like tilted racks) with some negotiating. More than a few folks in my HOA pay > $4.50/Watt for non premium paneled jobs while others pay ~ $3.50/Watt for similar array sizes/equipment. All the roofs are either flat concrete tile or mission tile. The difference is mostly in the knowledgeability and negotiating power of the customer. Read the book and sharpen your negotiating skills. Knowledge is power.
- Seriously consider tilting your array if at all possible. That's kill the $3.50/Watt price, but if you tilt 30 deg. off the horizontal, your annual output will be about 12-15% higher than if horizontal.
- As for may gray/June gloom, run PVWatts and use Palomar Airport for the weather data, or downtown. Then, make a few runs at different orientations. I'd use 10% system losses. The output will still be a long term estimate, but you'll probably find the optimum orientation about 10 deg. or so west of due south - not as much as you might think. Don't go crazy and face all the way west. BTW, optimum for T.O.U. pricing, and most efficient (lowest $$) for billing will be different, depending on your daily usage patterns and future likely SDG & E fooling with the peak pricing period, and will probably be further west, maybe to 30+ deg. west of south or so.Some homework will be necessary.
- @ 8,000 kWh/yr., you'll have a harder time getting to cost effectiveness as soon as larger users. a due south 30 deg. tilt system will probably generate ~ 1,600 kWh/yr. per nameplate Watt.
So, a 5kW system will meet 100%, but, contrary to common thinking, off setting an entire load is often not the most cost effective choice, especially if you stay on tiered rates, and perhaps more so if/when you switch to T.O.U. rates. Study the SDG & E rate structures. this is a real PITA, and there are no shortcuts, especially to optimize array size and match to use patterns, particularly with super off peak a possible EV, but the exercise is worth it.
- An EV will probably get you something north of 3 miles/kWh in terns of mileage. So, 12,000 miles/yr.--->>> ~ 4,000 kWh more electricity used.
- Get your roof inspected/serviced. Cheap insurance. You will not be sorry.

[Cartwright]

J.P.M:

Thanks for the info!
- All of the quotes I've gotten are tilted. I wouldn't consider doing a flat install. Maybe that is part of where the extra cost is coming from. Any guidance on what extra % to expect?
- I haven't started the negotiation process, that is part of the reason I'm trying to gather data. Once I narrow it down to my top 2 or 3 installers I'll start that process. I have a feeling that wanting a tilted, ballasted mount is adding more to the system than I originally thought.
- Your 5kW system estimate matches with what I'm being quoted. That is probably about the system I'll end up with
- I understand 100% offset isn't always ideal, but I expect to increase usage with the EV so I don't want to under-build, either
- Already have an appointment with a roofer! Even though it is fairly new, I agree it is a good idea to get it checked out...

I appreciate all of the input from you guys. By early next week I should have quotes gathered to start comparing and I'll post what I find for feedback.

[J.P.M.]

J.P.M:

Thanks for the info!
- All of the quotes I've gotten are tilted. I wouldn't consider doing a flat install. Maybe that is part of where the extra cost is coming from. Any guidance on what extra % to expect?
- I haven't started the negotiation process, that is part of the reason I'm trying to gather data. Once I narrow it down to my top 2 or 3 installers I'll start that process. I have a feeling that wanting a tilted, ballasted mount is adding more to the system than I originally thought.
- Your 5kW system estimate matches with what I'm being quoted. That is probably about the system I'll end up with
- I understand 100% offset isn't always ideal, but I expect to increase usage with the EV so I don't want to under-build, either
- Already have an appointment with a roofer! Even though it is fairly new, I agree it is a good idea to get it checked out...

I appreciate all of the input from you guys. By early next week I should have quotes gathered to start comparing and I'll post what I find for feedback.

You're welcome.

A 5 Kw size was an example only. Outside of a possible EV, your annual loads don't need to increase by edict. They can also decrease, as can happen with some thought and work. Not my money/house/life/NOMB, but some consideration as to an uncertain future may be worth the price of a slight oversize Again, your money/chjoice. Just walk in with your eyes open and not wearing rose colored glasses with respect to the future. A 5 kW system, or a bit more, or ~ 6-7 kW system if an EV is CERTAIN, may make economic sense when the penalty and cost of oversizing is treated as an insurance premium paid for future flexibility. But, just like standards of living that rise to meet (or exceed) one's income, if the EV doesn't happen soon, know that what usually happens is the electrical usage tends to increase to meet the increased generation. Then, when an EV does happen, the system becomes undersized. Just sayin'.

Ballasted systems present challenges, particularly on flat roofs due to weight, particularly for large(r) roof spans, and creep over time. I'm not sure San Diego allows them. Tilted racking is not as much of a challenge or as rare as some of the uneducated may think (my first practical, energy producing solar collector - a water heater - was tilted at 70 deg.), but still needs design and perhaps some review/stamp by a structural engineer, including roof attachment methods/details.

Get the dummies book and also get familiar w/ SDG & E tariffs and how they are changing. To repeat: a PITA, but the more you know, the better your result will be. Knowledge is power. It's also good to know the answers to the questions you ask, and fun as well as an education on vendor knowledge - or lack of it - to see the answers you get back.

I'd strongly suggest sticking with established electrical contractors who've been around at least 10+ years and sold solar for at least 5. A good vendor is worth a (slight ?) fairly negotiated premium.
They have a higher probability of having experience, knowing how to run a project, meet a payroll, and understand the value and fragility of both a customer and a reputation. They also have something besides solar if things go south.

Lastly, know that while Sunpower is good stuff, it's usually overpriced by ~ 15-25 % or so for what you get. Most all equal (electrical) size systems in the same location, orientation and service, using quality components, installed by compepent vendors will produce about equal annual output for longer than you're likely to own them. Sunpower's claimed "most efficient" line refers to an AREA efficiency. In terms of COST efficiency, they're at or near the bottom. Unless you place a high value on roof real estate, you'll do much better with most any other known panel in the most bill reduction for $ spent dept.

[Cartwright]

Okay, so I'm getting things narrowed down...

- Ballasted system is out. Regulations and the height of my parapet are such that penetrations would still be needed.
- I've gotten quotes from 6 installers so far, I have 2 more to do. None of them are quoting < $4/W, some as high as $5/W. I don't know how much to account for with my flat roof, but so far I'm disappointed with pricing.
- I'm only considering a tilted system, so I assume some of the extra cost is there.
- Got a hard sell on SunPower today. Equivalent output (fewer panels) is about 10% higher in cost over LG. The warranty seems great, but overall not sure if I'm sold.

Question if anyone has experience with torch-down asphalt roofs. Mine is about 8 years old and has a very minor leak that has shown up twice in about 5 years. I've called a couple of roofers and they won't touch it. They will only talk about replacing the whole thing. Does that seem right? Visually the roof looks great, there is just one spot with standing water and that is where it leaks. It seems like that could be built up some. Advice on whether I should bite the bullet and get a new roof? Any recommended material that might be more reliable and last longer?

Once I get the other 2 quotes I'll post specifics on here for feedback. If anyone has a roofer recommendation in San Diego, please PM me.

[J.P.M.]

Okay, so I'm getting things narrowed down...

- Ballasted system is out. Regulations and the height of my parapet are such that penetrations would still be needed.
- I've gotten quotes from 6 installers so far, I have 2 more to do. None of them are quoting < $4/W, some as high as $5/W. I don't know how much to account for with my flat roof, but so far I'm disappointed with pricing.
- I'm only considering a tilted system, so I assume some of the extra cost is there.
- Got a hard sell on SunPower today. Equivalent output (fewer panels) is about 10% higher in cost over LG. The warranty seems great, but overall not sure if I'm sold.

Question if anyone has experience with torch-down asphalt roofs. Mine is about 8 years old and has a very minor leak that has shown up twice in about 5 years. I've called a couple of roofers and they won't touch it. They will only talk about replacing the whole thing. Does that seem right? Visually the roof looks great, there is just one spot with standing water and that is where it leaks. It seems like that could be built up some. Advice on whether I should bite the bullet and get a new roof? Any recommended material that might be more reliable and last longer?

Once I get the other 2 quotes I'll post specifics on here for feedback. If anyone has a roofer recommendation in San Diego, please PM me.

1.) Your pricing will be higher due to the likely required tilting of the arrays.
2.) For most applications Sunpower is no where near as cost effective as say, LG/Solarworld/etc. However, with the added requirement of a tilted array, and probably a sawtooth arrangement of rows, S.P. MAY make sense here, or at least not be as overpriced in a relative sense as for a common application. S.P.'s big line is "most efficient". That's not most cost efficient - it's area efficient. In your case, the "area efficient" may count some. Reason: Less required area of the panels can mean less money for supports - in your case, the more expensive tilted kind. A 10% premium for the same tilted array arrangement MAY make sense. S.P. is good stuff. so is LG. I'd shoot for 5% if S.P. is to be the choice, and only then, for the same array arrangement/layout.
3.) In this application, it becomes more important than usual to NOT oversize the array. Unfortunately or otherwise, that means getting a better handle on what you what to accomplish, both in terms of offset of the elec. bill and long term cost effectiveness,and more/better guesses on the financial impact of sizing increments, both larger and smaller.
4.) Vendor quality/integrity, while always very important, also becomes more important in this case. That may mean an additional price premium on top of the adder for the non standard tilting arrangements.

Not trying to sound discouraging, and not my house/money/life/choice/etc., but with your relatively small current annual load, non standard array arrangement, and possible S.P. premium, you may find, after some serious and to me anyway, necessary cost analysis, that, in the cold, clear dawn of reality unclouded by emotion, solar for you may not have an acceptably high probability of becoming cost effective (paying back) in less time than you want to wait. You can usually save more up front and in the ling run by conservation measures, starting by simply turning stuff off and wasting less.


Then, there's the roof. Having lived in a home with 11 flat roofs at different elevations and sizes, I'll never have another home with any flat roof. Period. In your case, I wouldn't necessarily replace the roof. Before solar, I'd find the source of the leak, and then, equally important, find the cause, and then correct the problem at the cause - don't simply cover/bury it. Do this before any solar work. Keep in mind, if solar is a choice, you'll be adding about 2X or more as many roof penetrations as panels in the array. Do you want that many holes in a flat roof ? Maybe. Just know that the quality of the install will benefit future maint. requirements lower the leak potential. More perhaps practical justification for care in choosing quality vendors.

Take what you want of the above. Scrap the rest.

[Cartwright]

I want to "future proof" my system a bit and get an inverter that will be able to handle a Tesla Powerwall. The SE 7600 seems to be the main one on the market now that will be upgradeable. But my system is small enough that it doesn't require an inverter of that size. Am I losing anything if I get an "oversized" inverter? Someone said it isn't recommended because it can be inefficient.

Any truth to that?

[inetdog]

I want to "future proof" my system a bit and get an inverter that will be able to handle a Tesla Powerwall. The SE 7600 seems to be the main one on the market now that will be upgradeable. But my system is small enough that it doesn't require an inverter of that size. Am I losing anything if I get an "oversized" inverter? Someone said it isn't recommended because it can be inefficient.

Any truth to that?

The problem with an oversized inverter in an off grid battery system is that it draws a minimum "tare" current even when there is no load.
In the case of a GTI the effect does not have as drastic a consequence and in fact, because of the larger series control elements and and larger wires an oversized GTI may actually be more efficient that a right sized one. But the difference would be in one or two percent at most, IMHO.