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diy solar

Hey everyone, another new idiot to solar mastery

The new solar idiot

New Member
Joined
Mar 25, 2024
Messages
41
Location
Ohio
So I just purchased 6 used panels at a great deal (I think) and I am wanting to touch the world of solar. Yes i have done some searching but there are alot of on grid solutions and a bunch of manure for off grid in my situation. I do have a Tesla Model 3 I would #1 prefer to charge but that may not be feasible with what I have. My home is all electric and me being an enthusiast of everything I am looking to tinker but still be safe. The panels are 240w 30v 7.98a and I have room for up to 15( I can buy more than the 6 I have). I don't really want on grid and would prefer to charge my car though other suggestions are more than welcome. From what I read i need panels, an inverter, a controller, BMS and batteries. Haven't searched what is all on this site as I assume there is so much I would go cross eyed. Thx in advance. Also, not a Troll or Spam thanks
 
It takes a lot of solar to charge an EV.

Without too much detail, your 6 panels, on a great day, with all the right stuff, would probably add 20 miles of range, based on 3 mi per kwh.

Welcome to the insanity

I come up with the same number, and it's qualified by "when everything is perfect"... :p
 
People buy some used 240W panels for $25 to $50 apiece.
My sweet spot lately has been between 300W and 400W, for price, size & weight, quality.

The most cost effective way to use PV panels is with grid-tie inverter, and a net-metering plan with your utility. Look up if they allow that and what the deal (and utility rates) would be.

You might select a batteries-optional hybrid. That way you start out with straight GT PV, later get battery backup and time of use shifting if desired.
 
A quick pen & paper analysis suggests having at least 2X the watts of panels as your load. Since Tier-1 charging is 12A at 120VAC, that works out to 1440W. 2X of that is 2880W of solar. So, you'd need about double of what you have right now to even get started.

Where would these panels be going? Roof, ground mounts, how far away from your electronics/battery bank? A typical 30Vmp panel will put out ~40Voc at freezing, so you could safely wire three of those panels in series for a 150V limit controller. So, unless you plan on getting a high voltage controller, plan on sticking with 3S (that means three in series).

I tend to favor single-pole ground mounts, and my most recent V5.0 design holds six panels of the size you have. At 90V, you can position a 3S array up to 100' away from your battery with less than 2% voltage drop with standard 10 gauge wire. With two series strings per array, and rotating your arrays East to West over the course of the day, you'll be able to charge the EV at level one at least 8-9 hours per day.

A 48V system is likely to be the most efficient. With 2880W of solar, assuming battery charging starts at ~ 50V, then the theoretical max you'll see going out of the controller is 2880W/50V = 57.6amps. In the real-world, that's more likely to be 49-52A. A 60A controller will fit in here. MorningStar, Outback, Schneider, and Victron all make 150V controllers in this amp range. You might also look at Epever's Tracer 60A.

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The 2X rule also applies to inverters. If you need to supply ~1500W load (the EV), then get at least a 3000W inverter. I'm partial to Schneider products, and their Conext 4048 might meet your needs well. I personally have their 4024 for my workshop. It has excellent surge capacity, has a built-in generator connection, and is split-phase 120V/240V, so you might be able to ratchet EV charging up to tier-2 if you can limit charging to <10A. But, also look at the Outback and Victron products. I think for most of them, their smaller inverters need to be paralleled to get split-phase 240VAC?

If the primary goal is going to be EV charging, then your battery bank is not likely to need to be that big. A series string of eight 6V golf-carts will likely be fine to stabilize your system. CostCo has them for ~110$ now. If you want whole-house power 24/7 instead of just EV charging, maybe a battery twice that size would be appropriate.
 
People buy some used 240W panels for $25 to $50 apiece.
My sweet spot lately has been between 300W and 400W, for price, size & weight, quality.

The most cost effective way to use PV panels is with grid-tie inverter, and a net-metering plan with your utility. Look up if they allow that and what the deal (and utility rates) would be.

You might select a batteries-optional hybrid. That way you start out with straight GT PV, later get battery backup and time of use shifting if desired.
Thanks for your fast response. Was thinking I would get an email when there were response but didnt so sorry for the delayed response. Again I dont mind buying more panels as they seem to be the cheapest part though maybe i overpaid @ 60/each?! The parts looks to be affordable mostly the battery I was concerned with and buying the correct equipment.
 
A quick pen & paper analysis suggests having at least 2X the watts of panels as your load. Since Tier-1 charging is 12A at 120VAC, that works out to 1440W. 2X of that is 2880W of solar. So, you'd need about double of what you have right now to even get started.

Where would these panels be going? Roof, ground mounts, how far away from your electronics/battery bank? A typical 30Vmp panel will put out ~40Voc at freezing, so you could safely wire three of those panels in series for a 150V limit controller. So, unless you plan on getting a high voltage controller, plan on sticking with 3S (that means three in series).

I tend to favor single-pole ground mounts, and my most recent V5.0 design holds six panels of the size you have. At 90V, you can position a 3S array up to 100' away from your battery with less than 2% voltage drop with standard 10 gauge wire. With two series strings per array, and rotating your arrays East to West over the course of the day, you'll be able to charge the EV at level one at least 8-9 hours per day.

A 48V system is likely to be the most efficient. With 2880W of solar, assuming battery charging starts at ~ 50V, then the theoretical max you'll see going out of the controller is 2880W/50V = 57.6amps. In the real-world, that's more likely to be 49-52A. A 60A controller will fit in here. MorningStar, Outback, Schneider, and Victron all make 150V controllers in this amp range. You might also look at Epever's Tracer 60A.

View attachment 204830
The 2X rule also applies to inverters. If you need to supply ~1500W load (the EV), then get at least a 3000W inverter. I'm partial to Schneider products, and their Conext 4048 might meet your needs well. I personally have their 4024 for my workshop. It has excellent surge capacity, has a built-in generator connection, and is split-phase 120V/240V, so you might be able to ratchet EV charging up to tier-2 if you can limit charging to <10A. But, also look at the Outback and Victron products. I think for most of them, their smaller inverters need to be paralleled to get split-phase 240VAC?

If the primary goal is going to be EV charging, then your battery bank is not likely to need to be that big. A series string of eight 6V golf-carts will likely be fine to stabilize your system. CostCo has them for ~110$ now. If you want whole-house power 24/7 instead of just EV charging, maybe a battery twice that size would be appropriate.
Wow so this is a lot for a dummy like me but If I understand correctly, a 3000w inverter, a controller and some 6v club batteries from Sams may get me in the right direction? I was thinking If I couldn't charge the car I could use maybe 4 of them to power my pond pump and lights. Another stupid question, if I ran power directly to like a pond pump from a controller, Could I bypass batteries as I would only need daytime running anyhow? Long shot and most likely stupid question but that's how you learn i guess. And I suppose if I were running 6v batteries, I would prob need 20 of them to get to 120v wouldnt I?
 
Price depends on brand, quality, condition.
Some panels put out 14W/m^2, some 20W/m^2.

I wouldn't buy degraded panels or cracked backsheet etc. but some people have and are happy with them.


I've paid $0.19 to $0.37/W in recent years, for names like SunPower, REC, Qcells.

Some hybrid inverters can run batteryless, but a small lead-acid battery makes a big difference for motor starting surge.
 
Price depends on brand, quality, condition.
Some panels put out 14W/m^2, some 20W/m^2.

I wouldn't buy degraded panels or cracked backsheet etc. but some people have and are happy with them.


I've paid $0.19 to $0.37/W in recent years, for names like SunPower, REC, Qcells.

Some hybrid inverters can run batteryless, but a small lead-acid battery makes a big difference for motor starting surge.
From what I read Tesla charging is a hassle because you cant run dc to dc car battery. It has to go from dc to ac back to dc. idk
 
here is what I bought 6 of. some snail marks but nothing major and the pulled 33-37v testing with a basic multimeter
 

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If you can get net metering, that is best. Backfeed the grid from PV during the day while you're away.
Plug in to charge when you get home, set for whatever time has lowest rates.

Voc is a start. Then Isc. Finally Vmp & Imp which can be bad when the others are OK.

Plan and design your whole system, including inverter and PV array series/parallel, before buying more.

You've only spent $360 so far. Most of us, $thousands.
 
If you can get net metering, that is best. Backfeed the grid from PV during the day while you're away.
Plug in to charge when you get home, set for whatever time has lowest rates.

Voc is a start. Then Isc. Finally Vmp & Imp which can be bad when the others are OK.

Plan and design your whole system, including inverter and PV array series/parallel, before buying more.

You've only spent $360 so far. Most of us, $thousands.
I don't mind doing a grid setup. I just don't know what all is involved or needed. My neighbor has a full setup to grid but he like many others paid probably $35k and surprise it isn't sustainable and wont be for many years. That is one thing i do know is many of these companies will try to sell you on how after 15yrs it has paid itself off, but by then the panels are bad and your money deep again. I am just trying to be as cheap as possible as I would like to build fatherin the land of nowhere in the future and this knowledge seems priceless to me as a DIYer.
 
I'm doing my solar system with a friend I know that installs these for a living. I am gonna work with him from start to finish so I can learn as much as possible, and then expand the system later doing all the work myself. I will be net metering about 9kw of array, and after a year of use I will expand to cover all my electricity usage. I think I need at least a year of using the solar system and learning to see what I need to do in the future. Kind of excited for the experience, but I like learning new things.
 
I don't mind doing a grid setup. I just don't know what all is involved or needed. My neighbor has a full setup to grid but he like many others paid probably $35k and surprise it isn't sustainable and wont be for many years. That is one thing i do know is many of these companies will try to sell you on how after 15yrs it has paid itself off, but by then the panels are bad and your money deep again. I am just trying to be as cheap as possible as I would like to build fatherin the land of nowhere in the future and this knowledge seems priceless to me as a DIYer.

Find out the net metering terms offered in your area. And if you are forced onto a different rate schedule.

Consider whether you want backup while grid is down. If so, what kW simultaneous loads, kW starting surge ("LRA" on motor label, or about 5x operating current.) How may kWh per 24 hours and how many kWh at night.

Those figures can help you select an inverter.

Some AIO may cover everything you need. There are also component systems. Both kinds can be stackable for more total power. There are solutions from 3kW to 25kW or more, wide range of prices.

Hardware for strictly grid tie should cost about $1/W. One capable of using batteries may have more expensive inverter, but there is a wide range of prices. Batteries start around $250 per kWh, some are twice that, some higher.

Plan your system, note its capability, price it out, repeat a few times. Consider permit restrictions in your location for PV panel mounting.
There are some bargains out there, so once you know what you need you can see if they fit your plans or not.
 
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Batteries start around $250 per kWh, some are twice that, some higher.
This!!! I feel like for the most part inverters and panels are priced reasonably, but batteries not so much. I would like to eventually get at least 10-15kwh of battery backup, but that expense will have to wait. :)
 
This!!! I feel like for the most part inverters and panels are priced reasonably, but batteries not so much. I would like to eventually get at least 10-15kwh of battery backup, but that expense will have to wait. :)
This is solely my concern. i considered buying a salvaged battery pack from tesla and using some of the 4 bricks that come in it but im still banging my head that i have to do that with a battery sitting in my driveway. I am not looking to do whole home right now just getting my feet wet but at least with some purpose. I dont have interest in wasting money to try something, but rather building a setup that provides rather than waiting years for it to sustain itself(cost wise). Even if that means powering my pond :p if I cant justifiably power my car. MichaelK was pretty specific in parts needed. I like that, and really that is the direction i need to help better understand all of this. Is it gonna cost another 3k to charge my car or should i go grid and what is that cost? I know I could pull out a Solar sales person and waste their time for info but thats not me if not need be. Just trying to learn the basics before i jump into the pond 😊
 
I don't know how your state operates, but Texas has plenty of solar buyback electrical plans. Most plans down here you can grid tie and sell back to the grid for what you pay per kwh. Rates for us right now are .15 - .19 per kwh going to and from the grid. The best plans down here you can lock in the solar buyback rate for 36 months. Do you have a choice of electricity providers in Ohio? Texas is a strange situation with us being our own grid under ercot.
 
I don't know how your state operates, but Texas has plenty of solar buyback electrical plans. Most plans down here you can grid tie and sell back to the grid for what you pay per kwh. Rates for us right now are .15 - .19 per kwh going to and from the grid. The best plans down here you can lock in the solar buyback rate for 36 months. Do you have a choice of electricity providers in Ohio? Texas is a strange situation with us being our own grid under ercot.
Yes that is indeed available here in Ohio, and I believe i pay .15pkwh. I guess the part I dont understand is how do I tie in and does my provider have to come out and do anything? I would imagine something tracks the usage/upload and something transfers it outside of my incoming powerline. EDIT. SO Understanding in a grid system I need a Grid-Tie Inverter, this look like the panels connect in series or however you want voltage to stack to the inverter, then i has a pc style ac out that plugs into a wall outlet to go back to the grid. Part I am missing is how this is tracked and converted.
 
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