Solar panels cancelled due to concern over my roof's strength - experiences with this?

[Spalding]

Was primed to purchase Tesla solar panels for my 1913 craftsman style home, but after inspection Tesla cancelled. Aggravatingly, Tesla was very reluctant to say why - after much effort, a supervisor explained that there were concerns that the roof wouldn't be sturdy enough to support them. I was told that if I could have a structural engineer certify that the roof could hold at least 3 pounds per square foot Tesla might reconsider. Admittedly, the rafters visible in the attic are farther apart than they would be in modern construction. But I'm 200 pounds and walk around on the roof regularly; the Tesla site inspector was on the roof, too. Neither of us fell through, so I'm pretty sure the roof can withstand 3 pounds/sq. ft.

The rub is this - I can't seem to find a structural engineer willing to do calcs for my roof for less than $3,500. Obviously, if the roof is found sturdy enough pursuant to that review it might be worth the money to proceed, even though the expense would be wasted money. But if the roof is found to not be able to meet the Tesla standard, that money would be completely wasted. Structural engineer could also give advice on whether and how roof structure could be strengthened if it's a close call, but that would be even more money, both for the plan and for whatever construction would be called for. That would probably make installing solar financially unfeasible.

So the question: Has anyone gotten this response from Tesla solar before, and were they really willing to go forward if you provided proof that your roof was strong enough?

 

[jjrandorin]

Why dont you get a secondary quote from another company, and see if they have the same concern?

So the question: Has anyone gotten this response from Tesla solar before, and were they really willing to go forward if you provided proof that your roof was strong enough?

I dont work for Tesla or anything, but I have a return question for you. I am not a fan of trying to force a company to do work it clearly doesnt want to do, but thats my own personal opinion.

Hypothetically, if You got a structural engineer to sign off on this, went back to Tesla and they said something like:

"Ok, well, in order to proceed, you will need to sign this waiver that Tesla will assume zero responsibility for anything that happens with your roof, including roof leaks, roof damage, etc"

Would you sign such a waiver? If so, your risk tolerance is a lot higher than mine. If not, then when Tesla told you they didnt want to do the job due to their concerns over the roof, why would you still be pursuing having them do it?

 

[Spalding]

I had a second solar installer tell me the same thing, so I assume it's a standard industry practice and not just Tesla. Having a licensed structural engineer sign off on the roof is plainly for the installer's protection, and provides someone else to sue if there is a problem. Not completely illogical for any solar installer to do this. I assume the purchase contract has extensive language waiving liability and making the adequacy of roof structure the owner's sole responsibility.

Interestingly, in speaking with various structural engineers trying to get someone to sign up, most said no to the job. They mentioned that they were receiving many such requests regularly. Although unsaid, I'm fairly sure it's out of liability concerns by them, too. No one want to take on a job for $1,000 if it puts you at risk of a damage claim that might exceed $100,000. (Although the structural engineers' contracts I've seen have extensive waivers of liability and require the homeowner to waive or limit resultant damages, too.)

 

[Spalding]

And to the basic question of why would I might want to do business with a company that doesn't want me (which brings back memories of my dating days), the short answer is money. Tesla's solar panels were substantially less expensive than the other companies from which I've gotten quotes - in the range of $30k. For that kind of money I can handle some rejection.

 

[ewoodrick]

Was primed to purchase Tesla solar panels for my 1913 craftsman style home, but after inspection Tesla cancelled. Aggravatingly, Tesla was very reluctant to say why - after much effort, a supervisor explained that there were concerns that the roof wouldn't be sturdy enough to support them. I was told that if I could have a structural engineer certify that the roof could hold at least 3 pounds per square foot Tesla might reconsider. Admittedly, the rafters visible in the attic are farther apart than they would be in modern construction. But I'm 200 pounds and walk around on the roof regularly; the Tesla site inspector was on the roof, too. Neither of us fell through, so I'm pretty sure the roof can withstand 3 pounds/sq. ft.

The rub is this - I can't seem to find a structural engineer willing to do calcs for my roof for less than $3,500. Obviously, if the roof is found sturdy enough pursuant to that review it might be worth the money to proceed, even though the expense would be wasted money. But if the roof is found to not be able to meet the Tesla standard, that money would be completely wasted. Structural engineer could also give advice on whether and how roof structure could be strengthened if it's a close call, but that would be even more money, both for the plan and for whatever construction would be called for. That would probably make installing solar financially unfeasible.

So the question: Has anyone gotten this response from Tesla solar before, and were they really willing to go forward if you provided proof that your roof was strong enough?

One or two people is very different from adding a lot of distributed weight. Trusses are built to transfer the weight to the support points. 300 pounds is different from the entire load of the panels.

Your trusses were designed to handle your roof. The concept of adding solar cells just didn't exist then.

They cancelled because they are worried that there will be problems.

You may be able to get a Structural Engineer to look at your roof for a lot less. They may be able to give you an additional viewpoint if it is possible or not. But to certify it, if nothing else, they have to pay insurance just in case the roof fails, and you sue them.

 

[Rocket_man]

Depending on your jurisdiction, whoever installs the panels needs to pull a permit(s) and it will have to be inspected. I had three inspections on my installation including one from the fire department to make sure there is space for fire fighters to get on my roof. Anyway, if a Solar installer put a system on your house and the inspector failed the install, the solar installer is kind of stuck. The homeowner is likely to say it is the Solar's fault and they need to fix it. They normally don't get paid until the system is installed. Not worth the risk if you are the installer. My house is modern construction but I had a site survey from Tesla before everything was finalized. I think that was even before I signed off on the contract.

Your house is 110 years old. The solar would be on the roof another 20 years. You may need a new roof anyway to last the lifetime of the solar. That could be an opportunity to strip off the sheathing and sister additional joists and new sheathing. Yeah pretty expensive, but it is an old house and may be needed at some point regardless of solar.

 

[bradtem]

Perhaps talk to a company that does thin film panels, which are lighter, and might be within the tolerances on your roof.
Or talk to a neighbor who has a strong roof, and see if they want solar. Fill his roof -- you pay for more than half -- and share the power between the homes with a special line. I presume if done to code the power company would tolerate it. You could add a lower cost device like the Empower to meter your house or his to split up the bill. Needs a very friendly neighbour and a convenant after one of you sells your house. Or if you have a lot of land, don't put them on the roof, perhaps do bifacial vertical panels.

 

[charlesj]

In 2012 when I installed my solar panels, no batters until 2020, the city wanted an engineer's report that it could handle that 3lbs/ because the truss was made from 2x4s, not 2x6. It has concrete tiles on the roof by design, 10lbs/ and another 10 for workloads.
My engineer had a few choice words for the city plan checkers, schooled them on code that requires a design to support workload of 10lbs. 10 lbs- 3 lbs, still leaves 7 more lbs up there, just not on the panels.

 

[Vines]

Was primed to purchase Tesla solar panels for my 1913 craftsman style home, but after inspection Tesla cancelled. Aggravatingly, Tesla was very reluctant to say why - after much effort, a supervisor explained that there were concerns that the roof wouldn't be sturdy enough to support them. I was told that if I could have a structural engineer certify that the roof could hold at least 3 pounds per square foot Tesla might reconsider. Admittedly, the rafters visible in the attic are farther apart than they would be in modern construction. But I'm 200 pounds and walk around on the roof regularly; the Tesla site inspector was on the roof, too. Neither of us fell through, so I'm pretty sure the roof can withstand 3 pounds/sq. ft.

The rub is this - I can't seem to find a structural engineer willing to do calcs for my roof for less than $3,500. Obviously, if the roof is found sturdy enough pursuant to that review it might be worth the money to proceed, even though the expense would be wasted money. But if the roof is found to not be able to meet the Tesla standard, that money would be completely wasted. Structural engineer could also give advice on whether and how roof structure could be strengthened if it's a close call, but that would be even more money, both for the plan and for whatever construction would be called for. That would probably make installing solar financially unfeasible.

So the question: Has anyone gotten this response from Tesla solar before, and were they really willing to go forward if you provided proof that your roof was strong enough?

I can't say whether this construction is bad enough to warranty a rejection but I do know a SE firm in Laguna Niguel who will certainly charge less than your quote.

Our typical cost to engineer a set of drawings from them is much less than what you quoted. If you want a referral, PM me.

Typically the reasoning is that solar panels are installed and where they are installed you cannot walk on those areas. Roofs are typically designed strong enough so a crew could walk around, load the roof and replace if if needed. This is typically about 10 psf of live load. When the 3 psf of dead load is installed it displaces the 10 psf of live load in those areas.

I have put panels on roofs with 32", 72" and 96" rafter spacing and all were engineered and have no issues after years of wind loads. It might be you need a smaller installer who is looking to make it work, and will charge what it takes to make it work.

 

[kpanda17]

Was primed to purchase Tesla solar panels for my 1913 craftsman style home, but after inspection Tesla cancelled. Aggravatingly, Tesla was very reluctant to say why - after much effort, a supervisor explained that there were concerns that the roof wouldn't be sturdy enough to support them. I was told that if I could have a structural engineer certify that the roof could hold at least 3 pounds per square foot Tesla might reconsider. Admittedly, the rafters visible in the attic are farther apart than they would be in modern construction. But I'm 200 pounds and walk around on the roof regularly; the Tesla site inspector was on the roof, too. Neither of us fell through, so I'm pretty sure the roof can withstand 3 pounds/sq. ft.

The rub is this - I can't seem to find a structural engineer willing to do calcs for my roof for less than $3,500. Obviously, if the roof is found sturdy enough pursuant to that review it might be worth the money to proceed, even though the expense would be wasted money. But if the roof is found to not be able to meet the Tesla standard, that money would be completely wasted. Structural engineer could also give advice on whether and how roof structure could be strengthened if it's a close call, but that would be even more money, both for the plan and for whatever construction would be called for. That would probably make installing solar financially unfeasible.

So the question: Has anyone gotten this response from Tesla solar before, and were they really willing to go forward if you provided proof that your roof was strong enough?

Pay a skilled and certified roofer to produce a roof status report: roof beam size, spacing, and strength per square foot
Pitch measurement
Shingle and underpayment age and condition

Review this report with Tesla and or other solar installers
They do have the right to refuse

Home roof age of over 111 years, is def a concern
Just like a home with a 100 amp panel

Don’t shoot the messenger