- Tesla Solar, Home Battery & Backup Power – Part 2
- Tesla Solar Roof Tiles – System Activation – Part 3
When I first started this blog, I wanted to write more than just about coffee. Well, here is my first non-coffee post about our Tesla Solar Roof. The photos on this post are of our actual roof that was recently installed.
For those of you new to solar, I wanted to do a intro to solar power to help understand some of the terms and figures you’ll see.
Here is some electricity background that will help with solar shopping, you can skip over if you already know this. This is based off ideal conditions and simplified for our limited purposes of explaining solar.
You may own a microwave or toaster and see that it says 1000 watts, what does that mean? What are volts, amps and kilowatt hours (kWh)?
Volts x Amps = Watts
A standard U.S. household plug is 120 volts. Many homes also have a 240 volt plug for the dryer or an electric oven. A standard U.S. household plug is 15 amps, sometimes in the garage you will find a 20 amp plug. The number of amps that can be supplied to an outlet is determined by the size of the breaker and the gauge (thickness) of the wire.
If you do the math for your 1000 watt toaster, it means that 1000 watts/120 volts = 8.3 amps. You won’t see standard household appliances that use more than 1800 watts, because 120 volts x 15 amps is 1800 watts, which is the maximum amount of power a standard home outlet can deliver before the circuit breaker trips. You can use a watt meter like this to see how much power an appliance is using.
If you have an electric car you likely have a 240 volt outlet with a 60 amp breaker meaning it will deliver up to 14,400 watts or 14.4 kilowatts.
A kilowatt hour (kWh) is a measurement of energy and is the same unit you will find on your electric bill. Your 1000 watt toaster, if left on for one hour will use 1000 watt hours or 1 kilowatt hour (kWh). If let on for two hours it will use 2 kWh and so on. Tesla cars used to be badged with the kWh of the battery, such as 75 for 75 kWh, so it would take that amount of power to charge it from 0-100%.
The estimates vary, but for this example let’s say your Air Conditioning (AC) unit uses 6000 watts. Your AC will use 6 kWh for each hour it is on. If you run the unit for 5 hours, you will use 30 kWh of power.
Ok, why was all that important to explain, because solar is sold in kilowatts (kW) and you need to know the math behind the quote. Our solar system is quoted as 10.525 kilowatts and is estimated to produce about 15,800 kWh per year. If someone asks you what size your system is, they are asking what the kW size is.
Tesla used an estimate of about 4 hours of peak production a day x 365 days a year to arrive at the annual kWh (this estimate will vary by angle, orientation, region, system, installer and other factors) for our system. If we want to estimate the amount of energy our system will produce in a day we take the system size x 4 hours, for us that is 10.525 kW x 4 hours = 42.1 kWh a day, meaning we could run our AC for 5 hours a day with 12.1 kWh of energy for lights, TV, appliances, computers, etc. These are just estimates since weather, time of year, system performance and other factors will impact your production.
Your electric bill will tell you how many kWh you use on a daily average and you can use this to help estimate your solar needs and how much you want to offset. Check to see if your area has net metering (where your electric bill is based off off your net use as you will be giving any extra power you produce back to the grid). Excess power can go back to the grid under net metering and/or be stored in a home battery if you choose to have those as part of your system. We opted not to get a home battery because of the economics of current offerings. Please see Part 2 for more on backup power and Powerwall.
Our Solar Roof Project:
For 2020, the U.S. had a Federal Tax Credit of 26% for solar. In 2021, this was scheduled to go down to 22%. Fast forward to time of writing, the 26% has been extended into 2022. If you are considering solar and want to save some money, please check to see if you qualify for this credit as it may be a good reason to start sooner rather than later.
The Tesla Solar Roof Tiles were a good option for us, because we needed to install a new roof as part of our renovation process. However, if you have an existing roof in good shape, installing solar panels may be a more economical option, if you are ok with the aesthetics. South facing is the best elevation for solar in the U.S., east/west are the next best and north facing is the lowest producing. Our first solar quote had panels placed on the north facing roof, we ended up moving those to face south, east and west to optimize efficiency.
Many solar companies will not guarantee the production estimate, if they it will be over an annual basis. They can also say that was a cloudy year and there are a lot of variables they can use. Just know that it isn’t exact and that during the sales process they will say it is usually above the quoted production. I hope to talk more about this in a future post.
You will hear how solar panels are more efficient than solar tiles, this is true on a per square foot basis. Due to the nature of panels versus tiles you have more square footage available to you with tiles as they cover your entire roof and panels have to be placed in open spaces in your roof.
You may have also heard that Tesla customer service is awful, this is also partially true. I think this had to do with the fact that everyone was rushing to get their system installed before 2021 due to the reducing tax credit and they were just overwhelmed. When we could get a hold of our representative they were helpful and capable, but getting a hold of them was the hard part. At one point emails, voicemails and texts appeared to be going into a black hole, to the point where we were told to call the 800 number for a live person (which was pretty easy) and ask that person to tell our rep to call us back. In the end, due to delays, Tesla was willing to offer us a discount of 4% if they could not meet the install deadline.
We started this process in April 2019 by paying $1,000 for a deposit on a solar roof, it was fully refundable and we just decided to get our name on the list. We are not normally the early adopter types, so this was a first for us. At the time they were still on Version 2 of the solar tiles.
In June 2019, we were told that as our home was a large scale renovation, they no longer had spots open for their construction pilot program. They were only focusing on projects where replacing the roof was the only work that needed to be done.
Fast forward to May 2020, we reached out again as our project was moving along and they said they would be able to include us as part of their custom home program. It is easier for Tesla to only do roof replacements, because they don’t need to coordinate with any other contractors on site. Tesla was now offering Version 3 of the solar tiles.
In October 2020, we had been waiting for months to get an install date, something they absolutely will not commit to without all permits being in hand. After trying to track down our rep for weeks, we were told they arranged an install date on December 28, 2020. With the whole tax credit thing in mind, we kindly told them that was unacceptable and the next week they brought in a crew from Phoenix, Arizona to start work. Tesla actually paid for a crew to come in from another state and put them up in a hotel to install our roof.
At the very beginning I told the Arizona crew that I wanted to make sure all the wiring was done internally since the drywall and insulation had not yet been installed. They said they would do their best and said they were working on it several times when we followed up. They started with a dry-in process to weatherproof the roof.
At this point I realized why Tesla doesn’t like working on projects with other contractors on site. Home renovations have a lot of moving parts and a lot of subcontractors all trying to get in to do things in a certain order. This crew wanted to install the entire roof, however we still had scaffolding up and the stucco hadn’t gone up yet and through a lot of back and forth, it was decided that the Arizona crew would only do the second floor and leave the rest of the house for another crew once all the stucco was done and scaffolding was removed. On the last day I asked about running the wires in the house (instead of having exterior conduit run from the roof to the first floor) and I was told it just couldn’t be done without compromising system performance. I was given a bunch of excuses about how having the wiring and boxes outside would make it easier to service and that the techs wouldn’t need to go into my attic if there were any issues. I asked how often would there be issues that would require techs to come service my system and they never had a good answer, in the end I think they just didn’t want to do it.
At this point Tesla already promised to give us a 4% discount on the system since it wasn’t going to be installed by the end of 2020. We got all the other work taken care of and they said they would send a second crew in January 2021 to finish the job.
Everything went pretty smooth with the second crew, one thing of note is that they said they could absolutely run the wiring behind the walls and that it wasn’t a problem. The drywall and insulation was already in at this time, but they took care of it and also had someone come to patch the stucco and drywall where they had to remove it. They also had to rearrange some tiles the Phoenix crew installed in an area prone to afternoon shade for better system optimization.
After the install was all done Tesla sent out a third crew to inspect the work and spent a few days fixing some odds and ends to make sure everything was up to standard. At this point, I am pretty satisfied with Tesla. Sure there were delays and frustrations, but doing a big renovation project this stuff happens all the time.
I hope this provides you a good background of solar energy and Tesla solar tiles. At the time we had these installed (and at the time of writing), Tesla was the only company offering solar tiles and they only came in the one black/glass color. Hopefully there will be more offerings in the future. Our system has not been interconnected to the power grid or the house at this time as we are still finishing up the rest of the electrical system, I’ll do another post when it is up and producing power.
We also did look at solar panels, but the cost of them + a new roof would cost more than the Tesla solar tiles.
If you want more information or are interested in ordering, please use my referral link to save $500. This link can also be used to order a Tesla car and you will receive free supercharger credits.