I signed a solar city commitment that is currently in the design phase (2 weeeks now) so I’ve been reading these forums religiously. My design is for a 5.2 KWH system (using the 325w panels) and 1 Powerwall. This is currently 110% of our monthly usage but I still feel like I should increase to 6kwh... is that overkill?
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Looking forward to my install - few questions
- Thread starter novynova
- Start date
Definitely like to see pics and details! Is this a Tesla Panel install? Solar City technically doesn’t exist any longer, as far as I’m aware. (And I meant, are they using the new Tesla panels themselves, not just is ‘Tesla’ doing the installation.)
It is a Tesla energy install. I am using the Tesla low profile 325w panels (which cost more)
Finally got the design back.
Attachments
In my experience, if you have the space and financial capacity, you should opt to put as many panels as you can. You'll ultimately find a way to use all that you generate. We've gone from 3 ICE cars to now 2 electric and 1 ICE. Soon it will be all 3 electric--hence now using power wall to lower cost through TOU arbitrage.
my assumption is if/when we go electric with our vehicle, the cost of solar will be lower and it will be cheaper and possibly more efficient then. we dont currently expect to go EV for 3-5 years
I'm in the same boat. Waiting for my design from Tesla right now for a 9.3k system with a Powerwall. I intentionally left some unused space on my roof so that next year I can add a second Powerwall and spread out the cost a bit. If I add just one more solar panel at the same time that I add another Powerwall, the Powerwall plus one panel counts as another "system" and the entire purchase is subject to the 30% federal tax credit.
Shygar
Member
My SolarCity/Tesla install used Trina 300wH panels, 25 of them for 7.5kWh. I had the roof space so I didn't need to go for the 325wH panels.
SoundDaTrumpet
Member
Here are a few things for/against more capacity.
1. It's expensive to add on later in small increments. There a lot of fixed costs associated with installs. I asked about adding 1kW of solar and it is not worth it.
2. The saving from solar isn't great if you are charging an EV. It's only a few cents per kWh more when charging at night from the grid. Sizing for EV charging commits yourself to EVs for the life of your solar system.
3. Most annual electricity use goes to cooling the home. My AC efficiency is 10 SEER, and new ones are at 14 SEER minimum here in California. When my AC needs replacement, it is likely I will be overproducing solar because running the AC will use less power for the same cooling capacity.
I hope this helps.
1. It's expensive to add on later in small increments. There a lot of fixed costs associated with installs. I asked about adding 1kW of solar and it is not worth it.
2. The saving from solar isn't great if you are charging an EV. It's only a few cents per kWh more when charging at night from the grid. Sizing for EV charging commits yourself to EVs for the life of your solar system.
3. Most annual electricity use goes to cooling the home. My AC efficiency is 10 SEER, and new ones are at 14 SEER minimum here in California. When my AC needs replacement, it is likely I will be overproducing solar because running the AC will use less power for the same cooling capacity.
I hope this helps.
Regarding #1, fully agree and primarily my point in advocating doing so. The cost of adding a few more panels upfront is simply the capital cost of the panels and less so the labor of installing them.
Regarding pt #2, the suggestion was not to direct solar to charging EV--but taking advantage of time of use to offset your EV charging habits. If you outsize your system, what you generate during peak hours is 3X more valuable than what you spend on EV at night, so end of the day you will be greatly reducing your overall electricity bill. Furthermore, you would never need to fully size for EV given the time of use rate schedule. As to committing yourself to EVs, I would think that people once they have had EVs are unlikely going back to ICE--but even if you did, many cars going forward are moving to some hybrid/plug in systems.
Anyways, just suggesting if you have the space and financial capability, you should consider it.
WannabeOwner
Well-Known Member
Tangential thought:
I've never regretted the money I spent on things like this, where the payback was marginal/long/non-existent. Usually, in the end, energy prices went up, or some tax (like TOU) was imposed, or whatever, and it wound up in my favour. But I never included that unpredictable benefit in my justification, so my justification went more along the lines of "Charitable money I give to save the Pink Dolphins (insert favourite charity!) has no payback, why should I expect payback on contributions I make to reduce climate change?" - with the sight additional benefit of "charity begins at home"
I've never regretted the money I spent on things like this, where the payback was marginal/long/non-existent. Usually, in the end, energy prices went up, or some tax (like TOU) was imposed, or whatever, and it wound up in my favour. But I never included that unpredictable benefit in my justification, so my justification went more along the lines of "Charitable money I give to save the Pink Dolphins (insert favourite charity!) has no payback, why should I expect payback on contributions I make to reduce climate change?" - with the sight additional benefit of "charity begins at home"
eml2
Member
During the design phase of my system, I asked the installer if I could add more panels later when I got my EV. They said that the POCO usually requires a separate inverter when adding new panels. YMMV.
Shygar
Member
I had 24 panels and added 1 more panel more or less for aesthetic purposes and it was an additional $1000 for the extra panel.
another 4k will bring my system from 5.2kwh to 6.5kwh which is MUCH more than i use... decisions, decisions
Shygar
Member
Do you have anything that is gas powered that you can/want convert to electric? We have gas furnace, stove and water heater. I may consider an electric water heater in the future if our system is oversized even counting the model 3.
SoundDaTrumpet
Member
I am 50/50 with the electric hybrid water heater decision. I calculated ~4kWh of power per day on average. That's ~30% of the capacity of a Powerwall to cover heating water. Barring a gas outage, I think for backup gas makes sense. From a cost savings standpoint, electric hybrid is good. What makes things more complicated is that regulations force me to very expensive gas heating solutions for anything larger than 55 gallons. The rebates from my utility for electric hybrid are very handsome. I do wonder if federal rebate for this technology will be renewed for 2017.
We went with electric dryer. We also were in the middle of renovating other parts of the house so we decided to install electric floor heaters.
$4k less 30% for tax credit. so $2.8K for extra 25% production capacity. Not sure what your total cost is at this point--most likely above $16K, so cost/kwh should be averaged down. Trust me, you'll find a way to use up the extra capacity plus you'll love the fact that you really don't need to worry about turning off your lights
Additionally leaves you optionality for EV in the future.Similar threads
