Help me choose between Solar Roof or Panels

[jbl140]

Hello,

I've wasted so many hours on researching solar so I thought I might as well share here and seek some feedback.

We are looking to replace our wood shake roof (20yr+) with a composite and decided to get some quotes for solar panels as well. I had not initially expected the Tesla solar roof to be competitive for my 1750 sq ft home. But it turns out my roof area (3000 sq ft) and need for plywood layer actually make solar roof cheaper than a comparable sized shingle roof and solar panel (non-Tesla).

I've shared my options in the attached table. The cheapest option by far is a shingle roof with Tesla panels, but I would end up with either an undersized (4.08kW) or an oversized (8.16kW) system. Tesla solar roof is actually the 2nd best option here but the right capacity one. So, the decision should be simple then, right? Except I still have some concerns

• How do you add to capacity when tiles are integrated?
• Long term reliability - use of string inverter and pass-throughs with non-solar tiles could make repairs difficult. Have you seen any data on the ease of isolating and fixing faulty tiles?
• Overall aesthetics - while Tesla's website pictures look great, some of the actual installations don't look great. Some of the installations show some undulations. Is that normal?
• Install lead times - contract says 90 days but looks like people are waiting longer?

Thanks
Sri

 

[wjgjr]

Having a solar roof, I am a bit biased towards that, and I can say I like the look of our roof and have had no issues with undulations or other problems. But, since this technology is still rather new, a number of your reliability concerns may not manifest for some time. However, I do believe it is relatively easy for them to remove any individual shingles that might be defective and replace them.

As far as adding capacity, are you suggesting that your roof will have a number of non-PV shingles that you might want to replace later with PV shingles? It is an interesting question if so - our roof we maximized PV, so it is not something we would do. In principle, I don't see why they couldn't do it, though the inverters would also potentially need to be upgraded. I don't know, however, if that is something Tesla is willing to do. Again, since it is new tech, I expect there is not yet much of a market for that request.

One note on the solar panels - you indicate that 12 panels is too few and 24 too many. A number of other people seem to have had success with Tesla tailoring the number of panels to their need after they make the initial order. So, for example, you likely could get Tesla to setup a ~16-panel system that might provide about a 100% offset, assuming they can fit that number of panels on your roof.

If Tesla is saying 90 days on the solar roof, that is probably a fairly decent estimate - they seem to be pretty decent on forecasting that. I would double-check with them when signing and also understand their willingness to work with you on discounting the price should it move out into 2021 and you can't claim the 26% ITC. At least where you are, they should be able to work year-round.

 

[woferry]

Have you already had the site inspection from Tesla for the Solar Roof? I hope the decking costs were included there, I guess that's part of what jacked the regular roofing costs so high? It was a pretty significant extra cost in my Solar Roof, so I hope you really have an apples-to-apples comparison there and won't be surprised later.

On adding capacity later, I think the simplest answer for the Solar Roof is "you don't, plan ahead". Admittedly it should be easier with the larger / fewer number tiles in the v3 design than my v2, but there are still some tricks to balancing the strings in the Solar Roof that would make it very difficult to add later I think. But only places where the 45" non-producing tiles had been placed would even qualify for replacement with the PV Modules, as they only come in the one size.

Replacing a tile should be pretty easy, figuring out which one is bad would be quite difficult I suspect.

As far as looks I think a lot depends on how sound your structure is. I've definitely seen that the larger v3 tiles are less forgiving than v2 was, but if the roof is flat even the bigger tiles look great. My street now has a v2 (mine) and a v3 roof (installed several weeks back) on it (since you're in SJ PM me and I'll point you at it), and both look great in my opinion, but it's been very clear that this neighborhood's homebuilder did an excellent job, others just aren't as good. If the roof has started to sag in places the large tiles may serve to highlight the saggy areas.

 

[jboy210]

Our roof has some undulations. These are caused by the original builder putting too little framing for weight of the original roof tiles. Prior to our owning the home, the builder was sued by other home owners in the neighborhood and had to add additional support structure. However, they did not replace the plywood decking. As a result they are some subtle undulations. I really don't notice them and think the roof looks great. Much better than the tile roof it replaced and the composite shingle roofs some neighbors had done.

Since you need to put in decking if you don't have it, make sure that decking lies flat. The solar tiles are 17" H X 45" W and solid glass (i.e. not flexible at all) so if there is warping of the underlying decking it will be reflected in the solar tile runs.

Regarding repair-ability, when they were installing our roof they ran into some issue and though they may have a bad tile in a row. They were able to pop it up but the tile broke as did a tile below it. So they had to replace the 2 active tiles. FWIW, it turns out the issue was with their test box they use to test continuity during install. Once they connected the string it produced the expected output.

Our lead time was about 6 weeks.

No sure how to add capacity. We viewed it as non expandable and started with as much as we needed on the roof. We have 12+ kW and 2 PowerWalls and have no plans to add more solar capacity, but might add a 3rd PowerWall to further storage. We will make that decision after the PSPS (fire) season ends.

 

[gern]

Hi Sri,

I live in San Jose and had a Solar Glass roof and Powerwalls installed earlier this year. If you want to see a couple of houses in person with Solar Glass there are a few in my neighborhood; DM me for my address. I can’t answer most of your questions, but I would definitely recommend considering “oversizing” your system, as I found that our energy usage changed somewhat after installing solar and I am glad our system is larger than we thought we’d need.

-peter

 

[jbl140]

Thanks for the quick responses here
@wjgjr - I've gotten a range of proposals from 4.25kW for panels to 5.8kW for Tesla. As you can see, we've never exceeded 7000kWh per year. We have one electric car (Bolt) that we don't charge as often and we will be remodeling a shed to add A/C, so a little reserve capacity is good but don't want to oversize the system today.
Good suggestion on panels. I still haven't been able to talk to a customer service rep. By far, the lack of communication has been the biggest peeve so far. Someone texted last week, but I haven't gotten any response to my return text, email or voicemail so far.

woferry - No inspection yet. My initial proposal was for $32,972K, but after I emailed them about the plywood decking, they added a $3236 charge for roof deck replacement. But to make it apples-to-apples comparison with other quotes, I prorated the roof quote to also include a shed (200 sq ft) that needs a new roof. But I did not include gutters or gutter guards. Does the Solar roof include gutter replacement? If not, I am looking at another $2500-3000. Will DM for locations.

jboy210 - good to know that about ease of repair

gern - Would love to check out some installs in person. Will DM.

Overall, I am looking at $40K for Solar roof (w/gutters) vs. $36K for roof + Tesla panels.

 

[jbl140]

Peter, looks like your DM function is disabled?

 

[gern]

Peter, looks like your DM function is disabled?

Weird. I don’t know why you can’t message me. I just tried messaging you.

 

[jboy210]

Peter, looks like your DM function is disabled?

You might need to have a certain number of post before you can message someone.