Help us Elon !

[RocketDawg]

Curious: Did you look into their solar shingles as well? I will soon need a new roof and I know they are expensive, but...

How long do they last? Good idea, but would they need to be replaced before they pay for themselves? Not to mention - do we, in this part of the country, see enough sunshine to make them viable?

 

[SheltonChoked]

I have looked as well. But Electricity is too cheap.

If I lived in Hawaii, PR, or California, it would be a no brainer. But paying 10 cents a kWh makes the payout too long. But it is shorter than it was.

I expect the next generation of EV's will allow you to use the car for house power. you'd want to have the cars and the stuff you wanted the car to run on a sub panel. But a 400-500 mile range battery would keep you for most power outage situations.

 

[RBDog82]

View attachment 19524

The solar roof cost is supposed to be comparable to a new roof + solar panels. If I ever built a house, I’d probably go with the solar roof. The payback on just solar panels should be much lower than 20-30 years. However, once you introduce the Powerwalls, the payback does go up. For just solar panels (no Powerwalls), the cost for my house would be around $18k after the tax credit. I’ve got a TSLA referral code if any of y’all are looking at buying automobiles or energy products. Just shoot me a PM.

 

[patdog]

Exactly. The day will come when all roofs are solar panels and that will be a great day for everyone. But we're not there yet and i have no idea if it will take us 5 years or 30 years to get there.

 

[engie]

My bAd it was a 36KW generator for a house. 14 is about right for a big whole house unit.


Unless you have a huge house like 10,000 sq ft, you are doing something dumb to max out 200 amp service, much less average 200 amp draw.

Two AC units with electric heat in a 3000 sq ft house will use up 60% of that 200A service. Your system is only as good as your worst case scenario. Obviously most people won't go that route and will have heat pumps or gas. But it's not a terribly unrealistic scenario.

I have nothing fancy at all and thinking about this in terms of houses is a new angle for me, admittedly. I design and institute these temporary systems a dozen times a year, at least prior to covid. Systems that frequently run up to a half megawatt. Your 21A average household output is just mind bogglingly low to me. But I'm not used to thinking about it in terms of averages, just theoretical worst case scenarios.

 

[SheltonChoked]

And I'm thinking in a situation where you are on emergency backup power, you are not running all the lights, the electric pool heater, both ovens, and hosting a fondue party.

And there's the fact that genrac says the most sold sizes are 14-20kw.

I looked at my electricity usage over the last month. My max per day was 100 kWh. and that was with the pool pumps running 24/7 and running both ovens for the afternoon to cook weekly meals. And i'm in a 5500 sqft house with a pool. 2 x 3.5 ton ac units, Gas range, gas heat, gas dryer, gas water heater, and all LED bulbs, Radiant barrier, R20 walls. 4 of the people on my street have "whole home" generators and none are bigger than 20 kw.

Again, resistance Electric heat is dumb. But even in your situation , you could run one heater at a time on 30% of 200 amp service, which is 14 kw, which is what i said.

 

[SheltonChoked]

Exactly. The day will come when all roofs are solar panels and that will be a great day for everyone. But we're not there yet and i have no idea if it will take us 5 years or 30 years to get there.

The way prices are falling on panels, I'd bet it's closer to 5 than 30.

The big cost will be in installation. Which is good for US jobs. They cannot reroof your house from China, India, or Africa.

If they get the panel price down to $5/sq ft ( comparable to a nice shingle roof), Solar will be everywhere.

 

[Leeshouldveflanked]

Elon is hanging out in Austin Texas with Joe Rogan smoking Ganji and drinking Burbon.

 

[johnson86-1]

The way prices are falling on panels, I'd bet it's closer to 5 than 30.

The big cost will be in installation. Which is good for US jobs. They cannot reroof your house from China, India, or Africa.

If they get the panel price down to $5/sq ft ( comparable to a nice shingle roof), Solar will be everywhere.

That chart is utility scale solar, so it's a good bit different for rooftop.

Another thing that is going to push the payback period further out is that right now, retail users pay for a good chunk (and maybe all) of their capacity through just their use charges. If a lot of people start buying less energy because of solar panels, that capacity still has to be paid for, because people are still going to need power at winter peaks when solar will not be available at all and for summer peaks which typically occur a few hour after peak solar generation for a day. So rates will be shifted to bring the energy charges down and the capacity paid for through a fixed charge or a demand charge. If people really went all in on solar without it being paired with batteries, then non-solar users could theoretically get free energy during the day from dispatchable units because those units have to be run to be ready to serve load when solar generation drops off precipitously while load barely drops.

 

[SheltonChoked]

That chart is utility scale solar, so it's a good bit different for rooftop.

Another thing that is going to push the payback period further out is that right now, retail users pay for a good chunk (and maybe all) of their capacity through just their use charges. If a lot of people start buying less energy because of solar panels, that capacity still has to be paid for, because people are still going to need power at winter peaks when solar will not be available at all and for summer peaks which typically occur a few hour after peak solar generation for a day. So rates will be shifted to bring the energy charges down and the capacity paid for through a fixed charge or a demand charge. If people really went all in on solar without it being paired with batteries, then non-solar users could theoretically get free energy during the day from dispatchable units because those units have to be run to be ready to serve load when solar generation drops off precipitously while load barely drops.

The numbers on the y axis are different, but the declines are similar. It's not like the silicon is different.

Why would your example not push the payback period shorter? If we have to pay a fixed cost for power, now split over everyone, subtracting users means the cost per user must go up. Making solar (with storage) pay off faster. And why would you not pair solar with batteries?

With current tech, tesla recommends a 7 day powerwall storage with a solar roof. That should provide power through most events.
It's a different story in areas outside of the southern US as demand is not linked with the peak power times.