diy solar

diy solar

Where to begin! For my Epic Adventure!

offgridtesla

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Joined
Apr 7, 2022
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16
UPDATE! 05/05/2022

Okay! I made some changes and I would like some input please and thank you. I got a lot of flack for my original post (again this is all new to me and I really didn't understand the cost). Here is my mission and what I would like to do- I will receive my Tesla Model Y between July and August of 2022- and I want to build a solar array without battery storage (if possible). I know what you might be thinking but before you jump to a conclusion hear me out. What I intend to do is dollar-cost average Lithium batteries over an extended period of time. In essence, I intend on using the Tesla as battery storage- Furthermore, I might possibly be adding another EV to my fleet and typically no 2 vehicles will be driven at any given time. Thus, the vehicles will have constant storage capability based on my calculations/ driving habits-

If for whatever reason I intend on not getting a second EV or perhaps it falls through, I will continue on purchasing Lithium batteries on a dollar-cost average strategy.

Here are the meat and potatoes of what I need guidance on- What is needed for me to transfer from Solar to Tesla? Can you direct me on what will be required to make it work without using battery storage (a dummies guide)?

Second Question- Since I will be saving on battery storage costs, I would like to maximize output energy on the solar array. How many solar panels do you recommend for me to generate approximately 15-20 kWh per day and what wattage (my dream goal is 30kWh)? The location in which I am building will have direct sunlight from dawn to dusk. Before you kick my butt on this question (meaning if it is extreme or illogical to accomplish please educate me).

The panels will be placed 3-5 inches above gravel, temperatures under may be higher than usual (just an FYI or if it might be helpful)

I decided to do without a trailer and just build a small DIY cheap structure to hold the panels evenly and safely

The new budget for the project- $3200

AGAIN thank you.


The following is the original post unedited (thank you for your patients and kindess)

First I would like to start by saying thank you to the community and to those who help. Let us begin

I have a Tesla Model Y arriving between July and August of 2022. I currently am renting and my landlord is not entertaining the idea of Solar nor does he want to help in trying to combat the electricity hikes out here in California. As a conservative electricity user, my last month's bill was $400 for an 1100 sq foot home. I live out in San Diego and that has become a very common charge in this city... It is just truly expensive (period).

My dreams and ambitions did not want to be crushed, current gas prices are not getting better by any means and I am sure everyone reading this can relate. So I took it upon myself to dive deep into the world of solar and came across this thread/channel.

I want to build an off-the-grid solar array that can fully charge my tesla efficiently which consists of 75 kWh. This idea seems very ambitious due to the fact that my experience in all of this is close to zero. I seek guidance from anyone who is willing to give me their two cents and advice. I also have a Rivian that is expected to be arriving sometime in 2023 Which I also would like to be able to charge via the Solar array. Although, I do not need them to be charging at the same time (I am on a budget).

During the summertime, temperatures can reach an excess of 100 plus degrees, So I plan on building some sort of portable structure that can house everything that is required to run this project, having said that, I would also like the solar array to produce enough energy to cool the housing unit if need be.

What I have to work with:
On the side of the house, I have a large piece of flat land that does not get shaded throughout the day.
My budget is approximately $2500 I can add to that amount given more time. I prefer quality/ longevity.

In Addition, I do plan on taking this with me when I move.

Where do I begin? What do you recommend? Is it realistic to be asked to produce enough energy to charge a Telsa? If not, what is?

Again thank you to anyone who can help direct me.
 
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Will has a few videos on charging his teslas with solar, be sure to watch those.

He doesn’t drive a lot with his cars though.

How much do you drive? To charge 75kWh in a days solar is going to take a LOT of panels.

Figure 40 400W panels… and of course, most want to charge overnight, so, you will need a bank, LARGER than the vehicle bank… it can get quite costly.
 
Well I am guessing that you need a zero export system which leads to batteries or dumping excess power when you can't use it....because normally without a interconnect contract with the power company won't let you back feed into the grid....

Having 2 vehicles and only driving one seems like a waste....

I would mount panels on a trailer or make it a portable ground mount. If you are very picky with the components you choose you may be able to make a 2.5kW system. Used stuff might be a good option.
 
I buying a new Tesla and a new Rivian, but I need a cheap solar system because I'm on a budget.

These things just don't go together in my brain for some reason.
He didn’t say that, he said the system doesn’t need to charge BOTH vehicles at the same time because he is on a budget.

As to his price of $2500, I HOPE he meant for the portable structure… because solar enough to charge either electric vehicle from empty to full overnight is going to be huge…

Which is why I asked how much daily driving there is. Because, a small solar system can be made to top off a 50mile commute load… just not a full 200Mile daily commute…
 
He didn’t say that, he said the system doesn’t need to charge BOTH vehicles at the same time because he is on a budget.

As to his price of $2500, I HOPE he meant for the portable structure… because solar enough to charge either electric vehicle from empty to full overnight is going to be huge…

Which is why I asked how much daily driving there is. Because, a small solar system can be made to top off a 50mile commute load… just not a full 200Mile daily commute…
Thank you for taking the time to respond.

So I did further research since I posted this and I found that I do not need to Generate the full 75kWh per day. I calculated that I would need to at least generate 10-15kWhs and that is pushing it. I believe with my driving habits I can get away with only generating 8-9kWh per day. Do you know what it will take to make that happen?

To add, for now, the Tesla will only be used as a local driving vehicle. perhaps 100-150 miles per week. That number may vary.

correct me if I am wrong. My main focus should be on the battery storage capacity due to the fact that It can generate and hold the energy not used?
 
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I buying a new Tesla and a new Rivian, but I need a cheap solar system because I'm on a budget.

These things just don't go together in my brain for some reason.
I have budgeted and managed my cash flow for the next 2 years and the gap I have between the two vehicles is suitable for me financially. You are looking at it as if I am buying them both at the same time. There is more than a 1.5-year gap between the two vehicles and I have budgeted and saved for it to be affordable.

I limit myself on what I can invest for the solar array because between now and July that is what I can manage to afford. Given more time I can add to that and perhaps expand the solar project to accommodate my needs.

Thank you for your input.
 
Well I am guessing that you need a zero export system which leads to batteries or dumping excess power when you can't use it....because normally without a interconnect contract with the power company won't let you back feed into the grid....

Having 2 vehicles and only driving one seems like a waste....

I would mount panels on a trailer or make it a portable ground mount. If you are very picky with the components you choose you may be able to make a 2.5kW system. Used stuff might be a good option.
I was thinking of building a portable platform that can be moved easily with a trailer. To minimize costs I decided it probably be helpful to not invest in a mobile trailer. Once I move I can easily detach the solar array and rent a trailer or a moving truck to move everything.

When you state, 2.5kw is that figure generated per day or per hour? (I am really new to all this). Here is what I posted in a previous response, perhaps this will shed some light on my thought process.

So I did further research since I posted this and I found that I do not need to Generate the full 75kWh per day. I calculated that I would need to at least generate 10-15kWhs and that is pushing it. I believe with my driving habits I can get away with only generating 8-9kWh per day. Do you know what it will take to make that happen?

To add, for now, the Tesla will only be used as a local driving vehicle. perhaps 100-150 miles per week. That number may vary.

correct me if I am wrong. My main focus should be on the battery storage capacity due to the fact that It can generate and hold the energy not used?

Again thank you for your response and time.
 
Well I am guessing that you need a zero export system which leads to batteries or dumping excess power when you can't use it....because normally without a interconnect contract with the power company won't let you back feed into the grid....
I do not understand this statement, if you can be so kind to explain further?

I do not plan on feeding energy to the grid I need this project to be off the grid.
 
California law requires new houses to be built with rooftop solar, or alternatively participating in a community solar installation.

Anybody know if that lets the homeowner (or renter) get "net metering" benefits with some number of kWh from the community solar offsetting the consumption on their utility bill? If so, would be ideal for someone like OP.

 
Thank you for taking the time to respond.

So I did further research since I posted this and I found that I do not need to Generate the full 75kWh per day. I calculated that I would need to at least generate 10-15kWhs and that is pushing it. I believe with my driving habits I can get away with only generating 8-9kWh per day. Do you know what it will take to make that happen?

To add, for now, the Tesla will only be used as a local driving vehicle. perhaps 100-150 miles per week. That number may vary.

correct me if I am wrong. My main focus should be on the battery storage capacity due to the fact that It can generate and hold the energy not used?
A model Y and a rivian are cool toys and if you want electric toys they are sure to be fun choices. But if your goal is practicality and saving money, they are poor choices. You can get a 2022 Prius Prime with 8.8kw battery that can do 25 to 30 miles on electric and is more efficient per kw than either of your choices. Then, if more range is needed can average 65 to 75 mpg on gas. 9 gallons will reach over 600 miles. Cost is $30 to $38k and only $3k down. Then you can build a solar system that can charge it and never buy gas with 150 miles a week. If you want self driving, add Openpilot for $2000. It's not a cool car, but it is the most cost affective.

Sorry, I can't help with pricing for your system. I know used 250 watt panels are $63 plus shipping by the pallet. Growatt 5k $2000. And batteries $320 for 100ah 12v. All in Wills YouTube videos. He has built a system just to charge his Tesla with great details so should be easy to replicate.

Good luck. I hope you get your system for your toys.
 
I was thinking of building a portable platform that can be moved easily with a trailer. To minimize costs I decided it probably be helpful to not invest in a mobile trailer. Once I move I can easily detach the solar array and rent a trailer or a moving truck to move everything.

When you state, 2.5kw is that figure generated per day or per hour? (I am really new to all this). Here is what I posted in a previous response, perhaps this will shed some light on my thought process.

So I did further research since I posted this and I found that I do not need to Generate the full 75kWh per day. I calculated that I would need to at least generate 10-15kWhs and that is pushing it. I believe with my driving habits I can get away with only generating 8-9kWh per day. Do you know what it will take to make that happen?
A solar system is typically rated per hour.

At your location, a 2.5 kW system would generate on average about 4000 kWh per year, or close to 11 kWh per day (more in the spring-fall, less in the winter). A 3 kW system would generate about 4800 kWh per year, or on average about 13 kWh/day. A 3.5 kW system would generate about 5600 kWh per year, or on average about 15 kWh/day. Rough numbers (but in the ball-park). Again, that's on average throughout the year, less in the winter months. Below is a rough example using a 3 kWh system in your area broken down by month:

MonthSolar Radiation
( kWh / m2 / day )
AC Energy
( kWh )
Value
( $ )
January4.75344138
February4.74310124
March6.30439176
April6.40444178
May6.12440176
June6.43436175
July6.37442177
August6.88471189
September6.41422169
October5.66395158
November4.77327131
December4.39324130
Annual5.774,794$ 1,921
*Electrical rates were assumed at $0.40/kWh.

As you can see, with a 3 kWh system, you'd average as little as 10 kWh/day in Dec, but make almost 16 kWh/day in Aug.

If your landlord is okay with doing something like this (???), I would think the ROI would be pretty quick. Especially if you didn't add a battery bank to store energy and did all your EV charging during solar production hours. This might not be feasible for your schedule, but it would drastically reduce the cost of the system (and make it more efficient too). I understand it might not be ideal with only one EV, but with two EV's, one could always be charging on the system. Adding batteries is going to blow your budget out the window and significantly extend your ROI. Plus it makes no sense once you have two EV's... unless someone else would be driving the second EV during solar production hours as well.

Hopefully this helps!
 
Also measure the space you can put panels. From your earlier statements I got the idea you currently do not have the room for twelve 250watt used panels (from suntan solar).
Each panel is 65” x 39”

That is a 3kw system. New panels will go into a slightly smaller area for the same 3kw.

Panels are the cheap part, mounting will be expensive.

If you need to add batteries that will add a lot to the cost.
 
California law requires new houses to be built with rooftop solar, or alternatively participating in a community solar installation.

Anybody know if that lets the homeowner (or renter) get "net metering" benefits with some number of kWh from the community solar offsetting the consumption on their utility bill? If so, would be ideal for someone like OP.

Which is why I am aiming to do an OFF GRID SOLAR array.
 
What's wrong with this picture.. Purchasing ~$200,000 worth of vehicles and thinking a $2500 investment can make a dent in keeping them charged? I guess I better search around and find Will's Tesla setup info. -Bill
 
Which is why I am aiming to do an OFF GRID SOLAR array.

I don't understand your reasoning.
You may not understand the expenses and inefficiencies of the approach you're thinking of.

If community solar and “virtual net metering” is available to you, it may offer the best of all worlds, except for having power when grid is down.


Since California allows community solar as an alternative to rooftop, in its new laws requiring solar for new construction, there is a reasonable chance virtual net metering is included. But not clear from what I have been able to find.


It's a great idea, but if utilities have their way, won't get past that stage.




Building out your own panels and charger means either having the car parked during daylight hours and a charger that varies charge rate to match PV production, or huge battery to match charge rate and time of day to PV production rate and time of day. Cost and environmental footprint are an issue.
 
What's wrong with this picture.. Purchasing ~$200,000 worth of vehicles and thinking a $2500 investment can make a dent in keeping them charged? I guess I better search around and find Will's Tesla setup info. -Bill
I must also question the logic.

OP, if you plan on being at work during the day, how is your ev going to charge? If are one of the lucky whom work at home, ignore the following. A <3k pv system should, generally speaking, generate ~8'ish kwh meeting your minimum requirement, but if the ev is at work, how do you get the power into the car? Batteries are expensive. Server rack batteries currently appear to be in vogue. The average size of a economy based server rack battery being ~2.5kwh, with an average price <$2k. For $4k you could store ~10kwh which would meet the min requirement.
 
A solar system is typically rated per hour.

At your location, a 2.5 kW system would generate on average about 4000 kWh per year, or close to 11 kWh per day (more in the spring-fall, less in the winter). A 3 kW system would generate about 4800 kWh per year, or on average about 13 kWh/day. A 3.5 kW system would generate about 5600 kWh per year, or on average about 15 kWh/day. Rough numbers (but in the ball-park). Again, that's on average throughout the year, less in the winter months. Below is a rough example using a 3 kWh system in your area broken down by month:

MonthSolar Radiation
( kWh / m2 / day )
AC Energy
( kWh )
Value
( $ )
January4.75344138
February4.74310124
March6.30439176
April6.40444178
May6.12440176
June6.43436175
July6.37442177
August6.88471189
September6.41422169
October5.66395158
November4.77327131
December4.39324130
Annual5.774,794$ 1,921
*Electrical rates were assumed at $0.40/kWh.

As you can see, with a 3 kWh system, you'd average as little as 10 kWh/day in Dec, but make almost 16 kWh/day in Aug.

If your landlord is okay with doing something like this (???), I would think the ROI would be pretty quick. Especially if you didn't add a battery bank to store energy and did all your EV charging during solar production hours. This might not be feasible for your schedule, but it would drastically reduce the cost of the system (and make it more efficient too). I understand it might not be ideal with only one EV, but with two EV's, one could always be charging on the system. Adding batteries is going to blow your budget out the window and significantly extend your ROI. Plus it makes no sense once you have two EV's... unless someone else would be driving the second EV during solar production hours as well.

Hopefully this helps!
Nice idea alternating charging days between cars and basically taking advantage of the car batteries for the storage instead of buying batteries.
 
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