Will the "Beginner Friendly All-in-One Solar Power System" trickle charge a Tesla? Help!

[houts]

Question! Help anyone?

Just a follow-up: I have four 240watt 37v panels charging up my two 12v 100ah batteries.

Since I can't add more batteries to the bank (as it would go over 24v), can I add two 24v (or more) 100ah batteries together?
Ideally, I'd like to build a small battery bank for the winter.

Inverter x 1: PIP 2724LV-MR 24V 2.7kW 120V Inverter, 600W Solar
Solar panels x 4 (used): SST-240-60P Brand : Trina Solar Wattage : 240 Watts Voltage : 37.2V ( open current )
Batteries x 2: Weize 12V 100AH Deep Cycle AGM SLA VRLA Battery

 

[Supervstech]

Question! Help anyone?

Just a follow-up: I have four 240watt 37v panels charging up my two 12v 100ah batteries.

Since I can't add more batteries to the bank (as it would go over 24v), can I add two 24v (or more) 100ah batteries together?
Ideally, I'd like to build a small battery bank for the winter.

Inverter x 1: PIP 2724LV-MR 24V 2.7kW 120V Inverter, 600W Solar
Solar panels x 4 (used): SST-240-60P Brand : Trina Solar Wattage : 240 Watts Voltage : 37.2V ( open current )
Batteries x 2: Weize 12V 100AH Deep Cycle AGM SLA VRLA Battery

You certainly can add more batteries to the bank.
Just put them in parallel…
You would have to add 24V at a time, two 12V in series, or a single 24V…

 

[houts]

You certainly can add more batteries to the bank.
Just put them in parallel…
You would have to add 24V at a time, two 12V in series, or a single 24V…

I currently have two 12v 100ah batteries for my inverter (24v) requirements.
Are you saying I can add more 12v batteries without exceeding the 24v requirement but expanding my ah?

I thought if I added another 12v it would add up to 36v, so that is why I was wondering if I would need to replace the 12v with 24v so I can keep adding batteries. Do I make sense here? My apologies in advance if not.
My ultimate goal is to have a battery bank.

 

[Tomthumb62]

I currently have two 12v 100ah batteries for my inverter (24v) requirements.
Are you saying I can add more 12v batteries without exceeding the 24v requirement but expanding my ah?

Yes you can do that. You just need to wire them up properly.

Your current two 12v batteries are wired in series, which doubles their voltage to 24v.

So get yourself another two 12v 100Ah batteries and wire those the same way, to each other. Don't wire them up to the original two yet.

Then you will wire the two banks to each other, in parallel. To do that, you will take two more of the same thickness of jumper cables you are using on your two banks and wire them like this: Wire the Positive+ terminal of Bank 1 to the Positive+ terminal of Bank 2. Then do the name for the Negative- terminals.

Now the the two 24v banks are sharing their capacity (Ah) with each other. The whole she-bang is now a single 24v 200Ah bank.

You could do it again and end up with a 24V 300Ah battery bank.

With a large AGM bank, the problem will start to become that you don't have enough solar panels to produce enough power to fully charge the battery bank every day. AGM really NEEDS a complete and full charge at least once a week. If you regular discharge down to 50% and only get charged back up to 80% everyday, the AGM batteries don't like that. Lithium, no problem.

Also, if you haven't discovered yet, the other main limitation with lead acid batteries (especially AGM) is you cannot discharge them more than 50% on a regular basis, otherwise you risk causing permanent damage to their capacity (it will reduce). So your current 100Ah bank only had 50Ah that is usable and if you expand to 200Ah, only 100Ah is usable. Sucks, eh? That's a big reason why (besides easier charging) many people switch to lithium. Lithium batteries can safely use 80% of their capacity every day and even 90% occasionally. Even if you discharge a lithium battery 90% every day, you will usually still get more lifetime out of the battery than with AGM at 50%.

You will eventually want a shunt monitor, which attaches directly to the battery and gives you a truly accurate view of the state of your batteries capacity. They are as cheap at $16 and as expensive as $250+. I personally like the user interface and price of the Renogy one, which is currently on sale for $80. For AGM, such a monitor is fairly essential and it's still very useful for lithium. You can even set it to sound an alarm when your AGM bank has reached 50% so you can either turn off the load or plug your grid AC charger into to charge up the batteries if there's no sun.

 

[houts]

Yes you can do that. You just need to wire them up properly.

Your current two 12v batteries are wired in series, which doubles their voltage to 24v.

So get yourself another two 12v 100Ah batteries and wire those the same way, to each other. Don't wire them up to the original two yet.

Then you will wire the two banks to each other, in parallel. To do that, you will take two more of the same thickness of jumper cables you are using on your two banks and wire them like this: Wire the Positive+ terminal of Bank 1 to the Positive+ terminal of Bank 2. Then do the name for the Negative- terminals.

Now the the two 24v banks are sharing their capacity (Ah) with each other. The whole she-bang is now a single 24v 200Ah bank.

You could do it again and end up with a 24V 300Ah battery bank.

With a large AGM bank, the problem will start to become that you don't have enough solar panels to produce enough power to fully charge the battery bank every day. AGM really NEEDS a complete and full charge at least once a week. If you regular discharge down to 50% and only get charged back up to 80% everyday, the AGM batteries don't like that. Lithium, no problem.

Also, if you haven't discovered yet, the other main limitation with lead acid batteries (especially AGM) is you cannot discharge them more than 50% on a regular basis, otherwise you risk causing permanent damage to their capacity (it will reduce). So your current 100Ah bank only had 50Ah that is usable and if you expand to 200Ah, only 100Ah is usable. Sucks, eh? That's a big reason why (besides easier charging) many people switch to lithium. Lithium batteries can safely use 80% of their capacity every day and even 90% occasionally. Even if you discharge a lithium battery 90% every day, you will usually still get more lifetime out of the battery than with AGM at 50%.

You will eventually want a shunt monitor, which attaches directly to the battery and gives you a truly accurate view of the state of your batteries capacity. They are as cheap at $16 and as expensive as $250+. I personally like the user interface and price of the Renogy one, which is currently on sale for $80. For AGM, such a monitor is fairly essential and it's still very useful for lithium. You can even set it to sound an alarm when your AGM bank has reached 50% so you can either turn off the load or plug your grid AC charger into to charge up the batteries if there's no sun.

Thank you so much for the response. This was extremely helpful and put it into perspective.
If possible, and if you have time, might I ask for a slight diagram? I've tried drawing it, but I don't want to mess it up. I plan to purchase two more, probably within a week.

As for the lithium batteries, I intend to go that route, but not immediately. The cost of these batteries is insanely cheap-for now-as that two of them are the cost of one lithium.
The shunt monitor is a new one. I'll get one right away!

 

[houts]

Thank you so much for the response. This was extremely helpful and put it into perspective.
If possible, and if you have time, might I ask for a slight diagram? I've tried drawing it, but I don't want to mess it up. I plan to purchase two more, probably within a week. Also, I'll be adding two more 100ah batteries, so looking to do a 24v 400ah bank.

As for the lithium batteries, I intend to go that route, but not immediately. The cost of these batteries is insanely cheap-for now-as that two of them are the cost of one lithium.
The shunt monitor is a new one. I'll get one right away!

 

[Tomthumb62]

Thank you so much for the response. This was extremely helpful and put it into perspective.
If possible, and if you have time, might I ask for a slight diagram? I've tried drawing it, but I don't want to mess it up. I plan to purchase two more, probably within a week.

As for the lithium batteries, I intend to go that route, but not immediately. The cost of these batteries is insanely cheap-for now-as that two of them are the cost of one lithium.
The shunt monitor is a new one. I'll get one right away!

FIXED! The first image I posted was WRONG, don't use it, you'll start a fire. This one is correct. Sorry about that.

 

[Charleswgibbs]

View attachment 115983

That diagram shows a shorted out bank. Wires 1 and 3 shouldn't be there.

 

[Tomthumb62]

That diagram shows a shorted out bank. Wires 1 and 3 shouldn't be there.

Oh crap, you're right! I'll fix that.

 

[houts]

Oh crap, you're right! I'll fix that.

I was about to ask then what about the wires that would go to the inverter?

 

[Bud Martin]

View attachment 115983

Man! I hope you did not actually wire them up as shown, you are shorting out both battery banks.

 

[Tomthumb62]

Man! I hope you did not actually wire them up as shown, you are shorting out both battery banks.

Yes, so sorry about that. I fixed it. @houts make sure you use the updated image if you saw the first one.

 

[Tomthumb62]

I was about to ask then what about the wires that would go to the inverter?

Not my day, lol. EDITED to delete my previous comment.

A quick google search says that 1AWG would suffice for a 24v 2700W inverter. But I would confirm that with your inverter's documentation.

 

[Bud Martin]

That is why I am glad we always have the third eyes in this forum to check things out.

 

[houts]

Not my day, lol. EDITED to delete my previous comment.

A quick google search says that 1AWG would suffice for a 24v 2700W inverter. But I would confirm that with your inverter's documentation.

May I ask (forgive me) which wires would go to the inverter?

 

[Tomthumb62]

May I ask (forgive me) which wires would go to the inverter?

After you wire up your bank like the image I posted before, you would add 2 new wires. One goes from the + terminal on Bank 1 and the other goes to the - terminal of Bank 2.

Since it's 24V, it would be best to pre-charge the capacitors inside the inverter to avoid a big spark when you first connect the inverter to the battery. The big spark is slightly dangerous to you at 24v but could also damage your inverter. Not always, but could happen. You can buy an inexpensive resistor to help with this, or you can do it the redneck way with a contractor's pencil:

 

[houts]

After you wire up your bank like the image I posted before, you would add 2 new wires. One goes from the + terminal on Bank 1 and the other goes to the - terminal of Bank 2.

Since it's 24V, it would be best to pre-charge the capacitors inside the inverter to avoid a big spark when you first connect the inverter to the battery. The big spark is slightly dangerous to you at 24v but could also damage your inverter. Not always, but could happen. You can buy an inexpensive resistor to help with this, or you can do it the redneck way with a contractor's pencil:

Again, many thanks.

Last question: do you think, instead of buying two more 12v 100ah acid batteries, that I should just begin from scratch with a 24v 200ah lithium battery and start building a bank from there?

 

[Tomthumb62]

Again, many thanks.

Last question: do you think, instead of buying two more 12v 100ah acid batteries, that I should just begin from scratch with a 24v 200ah lithium battery and start building a bank from there?

That's a tough question. Each battery chemistry has it's pros and cons. The upside of Lithium is you can draw them down deeply - safely down to 20%, but they can do 10% occasionally. If you draw it down daily to 0% or 10%, you will severely shorten the life of the battery. Compared to AGM, which can only be safely drawn down to 50%, that's a big plus. Now higher-end sealed lead acid batteries, like the 6v ones (you'd put 4 in series to get your 24v) used for golf carts, those can be abused harder, even down to 20% often, just not every single day. But they're a bit pricier. The downside to lithium is the very popular LiFePO4 (lithium iron phosphate) is quite safe, it's not 100% safe - a punctured cell inside can still smolder though they usually don't get very hot. Just don't puncture it lol. Quality lithium is also more expensive in the short term. At an average $550 for a 12v 100Ah LiFePO4 battery, you'd need four of them to get a 24V, 200Ah bank. The good news is that's about equal to a 24v 400Ah AGM bank. So while the lithium are more expensive up front, you only need half as many batteries.

Another limitation of most LiFePO4 batteries is their BMS (battery management system, basically a small computer inside the battery) limits the discharge rate to 100A. I'm not sure the amp draw from a 24V 2700W inverter, but It's probably over 100A. So you would either need two 200Ah 24v batteries wired in parallel or a set of four 100Ah 12v batteries wired in 2s2p (like the image above I drew for you). That way you would get 200A of draw (100A from each side of the bank), which would be more than enough for your inverter. Best not to max out the discharge rate if you can help it. I haven't priced them out, but it's probably cheaper to get four 12v batteries than two 24v batteries.

A 24v 200Ah bank will set you back about $2000 or a 100Ah bank for about $1000. Or you can start looking at the rack mount batteries for cheaper, I see a 24v 200Ah one from Signature Solar for $1500.

Short version is - you already have a couple of AGM batteries. Why not just buy a couple more and use your batteries for 3-5 years, which will be about the expected lifetime of AGM (lithium will last 10 years typically)? If you hadn't already bought and used your batteries, I would probably encourage you to the lithium route, but that's not the cards. It doesn't make financial sense to switch out, unless you can afford to and can find a use for your AGM batteries. You can't easily mix chemistries unless you really know what you're doing or have a bunch of more equipment going on (you should never connect lead acid and lithium batteries into the same bank as they require different charge profiles and discharge at different rates - a fire could ensue).

 

[houts]

Many thanks to Tom and Bud for your help. It has squelched the fear of all-things-solar and being to move forward.

I'll leave this other question if anyone has the time or willing to answer. If needed, I can provide photos or information.

Here is my current set-up:

Inverter x 1: PIP 2724LV-MR 24V 2.7kW 120V Inverter, 600W Solar


Solar panels x 4 (used): SST-240-60P Brand : Trina Solar Wattage : 240 Watts Voltage : 37.2V ( open current ) wired in parrallel

Batteries x 2: Weize 12V 100AH Deep Cycle AGM SLA VRLA Battery


SolarWatch program (runs on my laptop and plugged into inverter via USB)




I just added two more solar panels (for a total of four), but still am only pulling 330-400(max) watts with the sun out, no shade, and direct hits on all panels. I have them hooked in parallel since each panel has a 37.2v capacity, and if I put in a series, it would go beyond the 60v my Inverter can handle. My MC4 lines run 90ft into my garage (where the inverter sits).

I've tinkered with the settings on the inverter to no avail. Any thoughts on what could be the issue?

 

[Tomthumb62]

I just added two more solar panels (for a total of four), but still am only pulling 330-400(max) watts with the sun out, no shade, and direct hits on all panels. I have them hooked in parallel since each panel has a 37.2v capacity, and if I put in a series, it would go beyond the 60v my Inverter can handle. My MC4 lines run 90ft into my garage (where the inverter sits).

Have you done any of this:

• tested the actual voltage of each panel with a multimeter?
• also tested the voltage at the end of you 90ft lines?

Say you're getting 30-35V for each panel when you test them from the short MC4 leads that come directly of each panel, but then you test at the end of the 90ft lines and you're only getting 23v. In that case, you don't have enough voltage to charge your battery. It's call voltage drop, which can happen if you use too small of cable for too far of a distance. Now maybe you have just enough voltage, but the end result is you're losing a lot of power (wattage) due to voltage drop.

I'm not much familiar with 24v systems so I won't comment any more. But it seems strange to me that the integrated charge controller in your inverter can't accept more than 60v? I mean if you got smaller panels, say some 100W ones that have a Voc of about 21V, then you could put at least two of those in series for a few more voltage points. My pretty basic charge 30A controller can accept up to 100V.