100% off-grid system from the ground up, literally.

[Trukinbear]

Sounds great, will do... For now, you can read up on the other guy who already used a Midnight Classic MPPT charger on a tweaked wind profile to charge his 48v using the Prius: https://www.solarpaneltalk.com/foru...idnight-classic-as-voltage-converter-possible

Mine is a Prius Gen IV with the lithium 207.2v, and the earlier ones used nickel-metal hydride 201.6v (although both types have quite a operating voltage range, like maybe 190-240v DC), if I don't try this later using an MPPT charger, then for now I will use the APC SURT5000XLT UPS I have now and pipe the 240v AC output to a gen input on an all-in-one inverter like the Sol-Ark, to use it as a backup source for charging the 48v bank.

For a minute there I thought you were linking to my post about using Classic 250's... I can't find where I posted that but my work on this idea predates that post. I'm sure many other people have had the same idea as I - pretty sure I'm late to the game. Don't use it set to MPPT, set it to PWM as though you were using wind, or hydro which is selected when you tell the Classic 250 you are doing wind/hydro.

 

[Skysthelimit]

I live in Utah as well, planning an off-grid home in a Self-Reliance community North of Delta, I just bought a LiFePO4 battery system from Treeline Power Systems: https://www.treelinepowersystems.com/LiFePO4-48V-512v-280ah-14kWh-Battery-System-wIth-BMS_p_37.html They come with the 280 ah cells. I just received the shipment a couple days ago. I ordered 2 of the 14 kW/h 48v banks which is 32x cells total (which came with 2 BMS, one per bank, I got the 200a BMS option with mine). It came to $6548 shipped. The guy, Randy from there (Colorado) was very friendly and answered all my beginner questions and I felt good about getting from them. I was originally looking into buying direct from a China company, but the turnaround was something like 50 days doorstep to doorstep. This guy took about 2 weeks to assemble, test, and get them to me. The ones I got here don't come with any case or anything, just the cells and BMS units, all pre-wired, tested, and unconnected for transport. I haven't reconnected all the BMS and tested myself yet, since I am still planning my solar install soon, so maybe later I could report about how well they work. Hoping to try them soon, supposedly this should provide 28 kW/h with 2 48v banks in parallel. The guy said these BMS do balance on discharge, and have full over-voltage/under-voltage cutoff, and over-temp/under-temp cutoff, so they are fully protected. One reason I also decided to go with a local US supplier, is this guy says he will do advance replacement, so if I get a failed cell ever, he says he can ship new one first. He also said they do advance replacements on other parts they sell too. This is my first purchase from them but maybe I will look into other stuff from them later. He doesn't sell Sol-Ark though, so I am holding out, because I think I want a Sol-Ark 12k EMP hardened inverter once I have it in my budget. For now, I will only use my Victron 250|100 and DC only loads until a bit later when I can afford a Sol-Ark. I have 16x 400w solar panels, these batteries, Victron MPPT charger, combiner boxes, all the cables and connecting hardware, hopefully enough to run a 48v 20,000 BTU DC heater I bought, and some LED DC lights, enough to get me through Winter and keep the Motorhome warm so the pipes don't freeze. I think 28 kW/h should allow me to run a couple nights with that size 1200w heater. Eventually I want to get the 48v mini-split heat pump to heat and cool.

Hi there. Just checking in to see how your system is working for you. I'm still researching and trying to determine how much of a battery bank to build and which cells to go with as well as which inverter or inverters to buy. I like the Sol-Ark, like you do, but probably only need the smaller, I think it's an 8k model. The builder of my barn/house in the Cedar City area will probably get going on the building project next week so I have some time to decide on what to buy. Trying to layout the living area and other areas that will require power so I can determine just how much power I'll need to run totally on battery power for lets say, two days. Anyway, I pray your system is working smoothly and would appreciate any feedback you can give me, namely, do you have enough power, was your battery bank overkill for your needs, etc. Cheers!

 

[Samsonite801]

Hi there. Just checking in to see how your system is working for you. I'm still researching and trying to determine how much of a battery bank to build and which cells to go with as well as which inverter or inverters to buy. I like the Sol-Ark, like you do, but probably only need the smaller, I think it's an 8k model. The builder of my barn/house in the Cedar City area will probably get going on the building project next week so I have some time to decide on what to buy. Trying to layout the living area and other areas that will require power so I can determine just how much power I'll need to run totally on battery power for lets say, two days. Anyway, I pray your system is working smoothly and would appreciate any feedback you can give me, namely, do you have enough power, was your battery bank overkill for your needs, etc. Cheers!

Well, I am ordering the Power Peak solar ground mount for 24 panels today actually, so I still don't have my system up and running yet. I had decided to go with the 28kW/h battery solution but haven't actually tried it yet. I have also learned some other things like, how that kW/h 'rating' can vary, like as in, maybe it can approach 28/kW/h if you run the battery cells in deeper cycle to their max, maybe in their full charge discharge cycle (like say 2.5v - 3.65v), however, if you want to get maximum cycles out of the batteries, you might only want to cycle the cells maybe in range of 3.2v - 3.35v or up to 3.4v or something if you want them to last longer, but this of course will cut away from your kW/h rating (that you should factor in about a -20% correction in the advertised kW/h rating if you decide to use a 'long-life' cycle strategy).

For me, coming from the city life, living in an inefficient home, and moving to a passive home strategy in an off-grid environment, it is hard for me to gauge how much power I will require at this point, so I decided that the current setup with 32x 280ah cells should be a good start, and if I need more I can parallel in more banks later (just going by the seat of my pants, no calculators for me here). And just FYI, I probably could've saved half the money by just buying raw battery cells and own BMS's on the 48v system, but the seller in Colorado I bought from is a middle man, so it cost a little more there, but he does offer advance replacement warranty, and 7 year performance warranty on the cells, so the price on the battery stuff can really vary too, depending on your needs.

More recently, I also am building a 12v battery system for my RV with 8x 280ah cells, and this one I am buying direct from AliExpress, and bought my own OverKill BMS's for that system, it is a lot cheaper this way, but no advance replacement or performance warranty. So the jury is still out on which path is better, still waiting for those 8x cells to get here from the China seller.






As far as the Sol-Ark, if you look at the 8k vs 12k, the price isn't much different between them, but the 12k is 'stackable' (up to six units) for future, can support 3-phase, more PV capacity for future growth, etc., so for me the 12k is the way to go... In general, it is more future-proof, and is like $750 more is all.

From: https://practicalpreppers.com/sol-ark-8k-vs-sol-ark-12k/

 

[Skysthelimit]

Well, I am ordering the Power Peak solar ground mount for 24 panels today actually, so I still don't have my system up and running yet. I had decided to go with the 28kW/h battery solution but haven't actually tried it yet. I have also learned some other things like, how that kW/h 'rating' can vary, like as in, maybe it can approach 28/kW/h if you run the battery cells in deeper cycle to their max, maybe in their full charge discharge cycle (like say 2.5v - 3.65v), however, if you want to get maximum cycles out of the batteries, you might only want to cycle the cells maybe in range of 3.2v - 3.35v or up to 3.4v or something if you want them to last longer, but this of course will cut away from your kW/h rating (that you should factor in about a -20% correction in the advertised kW/h rating if you decide to use a 'long-life' cycle strategy).

For me, coming from the city life, living in an inefficient home, and moving to a passive home strategy in an off-grid environment, it is hard for me to gauge how much power I will require at this point, so I decided that the current setup with 32x 280ah cells should be a good start, and if I need more I can parallel in more banks later (just going by the seat of my pants, no calculators for me here). And just FYI, I probably could've saved half the money by just buying raw battery cells and own BMS's on the 48v system, but the seller in Colorado I bought from is a middle man, so it cost a little more there, but he does offer advance replacement warranty, and 7 year performance warranty on the cells, so the price on the battery stuff can really vary too, depending on your needs.

More recently, I also am building a 12v battery system for my RV with 8x 280ah cells, and this one I am buying direct from AliExpress, and bought my own OverKill BMS's for that system, it is a lot cheaper this way, but no advance replacement or performance warranty. So the jury is still out on which path is better, still waiting for those 8x cells to get here from the China seller.


View attachment 27263



As far as the Sol-Ark, if you look at the 8k vs 12k, the price isn't much different between them, but the 12k is 'stackable' (up to six units) for future, can support 3-phase, more PV capacity for future growth, etc., so for me the 12k is the way to go... In general, it is more future-proof, and is like $750 more is all.

From: https://practicalpreppers.com/sol-ark-8k-vs-sol-ark-12k/

View attachment 27265

Thanks for replying: I see you and I are running at pretty much the same speed. We both have some of the components needed for the off-grid living in a permanent structure, and we both want to upgrade our mobile/RV home. I appreciate you sharing the info on charge and discharge of the lithium batteries. If I would have thought about it, after watching umpteen youtube videos, it would've dawned on me that when they check the capacity of the cells in question, they have to discharge them to the point where the bms or inverter shuts the test down....duh.
After spending x thousand of dollars on a battery bank, I will not routinely discharge them down to the lower limit as I cannot afford to buy another set of these batteries, prematurely. I've heard some say they were bottom balancing and other say they were top balancing so I'll have to see what the best way to go is when that time comes. I need to keep a running tally on the price of the 280 ah cells and try to jump in the game when the price seems best. I will almost certainly be buying raw cells and building my own pack, up to 48 vdc, so please let me know how you like the seller and buying experience, time it took to get them, etc, to the point you're comfortable with. All info. is much appreciated.

 

[Samsonite801]

Thanks for replying: I see you and I are running at pretty much the same speed. We both have some of the components needed for the off-grid living in a permanent structure, and we both want to upgrade our mobile/RV home. I appreciate you sharing the info on charge and discharge of the lithium batteries. If I would have thought about it, after watching umpteen youtube videos, it would've dawned on me that when they check the capacity of the cells in question, they have to discharge them to the point where the bms or inverter shuts the test down....duh.
After spending x thousand of dollars on a battery bank, I will not routinely discharge them down to the lower limit as I cannot afford to buy another set of these batteries, prematurely. I've heard some say they were bottom balancing and other say they were top balancing so I'll have to see what the best way to go is when that time comes. I need to keep a running tally on the price of the 280 ah cells and try to jump in the game when the price seems best. I will almost certainly be buying raw cells and building my own pack, up to 48 vdc, so please let me know how you like the seller and buying experience, time it took to get them, etc, to the point you're comfortable with. All info. is much appreciated.

Yeah cool, maybe we can share ideas as our builds go along, help avoid pitfalls as this is a diverse technology with lots of ways of doing the same thing, and there are many potentially more costly ways of learning about best practices than others. This forum is a gold mine though for learning best practices and saving the most money along the way.

Here is the seller I bought my latest cells for the 12v RV system from (Aliya's Battery Store):

1179.9US $ 5% OFF|8pcs/lot Lifepo4 3.2v 280ah Lithium Iron Phosphate Cells For 24v 280ah Rv Battery With Bus Bars - Rechargeable Batteries - AliExpress

Smarter Shopping, Better Living! Aliexpress.com

www.aliexpress.com

There were some other sellers I had looked at, at cheaper price points, but this one had some good reviews I could read about. There are also other forum threads here (which I did not see until later, where people have received products from, and give high regards to, as selling high-quality matched 280ah cells).

As far as balancing goes, my thought based on what I've learned here, is that bottom balance or top balance in all practically doesn't really matter, the main point being that if you look at the charge curve of a LiFePO4 cell, it is fairly flat in the middle of the 'knees' (on the bottom of SOC, and top of SOC), so the point being that when balancing, if you get all the cells into one of the 'knees', either on bottom end or top end, it will ensure that all cells are at the same SOC (back in sync, to a known SOC), because in the middle of SOC somewhere, the voltage is too similar, so they could all be far out of SOC sync. Once they are in sync after balancing, then you know (once you wire them all in series again), that they can 'breath' to the same depth and no one cell can drag the whole bank down. When a cell might be out of sync with the rest, it may hit its low voltage limit where the BMS will cut off the whole pack when all the other cells may still have more SOC...





For me, I will just do a standard top balance, maybe up to 3.5v or 3.6v or something (or do the 3-stage one, where you go like 3.4v, then 3.5v, then 3.6v), just as long as you get it up into that knee without going so high to cook it. Some people go to 3.65v which is still perfectly safe. I don't think it's all that critical how high you go for the balance, as long as we are well into the knee, they should all be pretty much in sync by then anyways.

 

[Skysthelimit]

Yeah cool, maybe we can share ideas as our builds go along, help avoid pitfalls as this is a diverse technology with lots of ways of doing the same thing, and there are many potentially more costly ways of learning about best practices than others. This forum is a gold mine though for learning best practices and saving the most money along the way.

Here is the seller I bought my latest cells for the 12v RV system from (Aliya's Battery Store):

1179.9US $ 5% OFF|8pcs/lot Lifepo4 3.2v 280ah Lithium Iron Phosphate Cells For 24v 280ah Rv Battery With Bus Bars - Rechargeable Batteries - AliExpress

Smarter Shopping, Better Living! Aliexpress.com

www.aliexpress.com

There were some other sellers I had looked at, at cheaper price points, but this one had some good reviews I could read about. There are also other forum threads here (which I did not see until later, where people have received products from, and give high regards to, as selling high-quality matched 280ah cells).

As far as balancing goes, my thought based on what I've learned here, is that bottom balance or top balance in all practically doesn't really matter, the main point being that if you look at the charge curve of a LiFePO4 cell, it is fairly flat in the middle of the 'knees' (on the bottom of SOC, and top of SOC), so the point being that when balancing, if you get all the cells into one of the 'knees', either on bottom end or top end, it will ensure that all cells are at the same SOC (back in sync, to a known SOC), because in the middle of SOC somewhere, the voltage is too similar, so they could all be far out of SOC sync. Once they are in sync after balancing, then you know (once you wire them all in series again), that they can 'breath' to the same depth and no one cell can drag the whole bank down. When a cell might be out of sync with the rest, it may hit its low voltage limit where the BMS will cut off the whole pack when all the other cells may still have more SOC...


View attachment 27273


For me, I will just do a standard top balance, maybe up to 3.5v or 3.6v or something (or do the 3-stage one, where you go like 3.4v, then 3.5v, then 3.6v), just as long as you get it up into that knee without going so high to cook it. Some people go to 3.65v which is still perfectly safe. I don't think it's all that critical how high you go for the balance, as long as we are well into the knee, they should all be pretty much in sync by then anyways.

Obviously, you've got a bunch more knowledge under your belt. For grins, I checked out what 32 of those cells would cost and it came to a bit over $4300.00...ouch! Then I'd need a Sol-Ark, wiring, BMS, and a second job... Think I'll just keep watching the prices and pray they go down in the near future. Keep me posted and I'll do the same. Oh, I was going to ask where you got the Sol-Ark price comparison and where you plan on buying the unit from? I found a store in St. George, UT that is supposed to be a dealer, but so far, they are slow to respond to inquiries and I don't know if they actually have any to sell. I hope to hear back from them tomorrow. Maybe, when your ready, we can make a deal on buy two, in hopes that we get a better price.

 

[Samsonite801]

Obviously, you've got a bunch more knowledge under your belt. For grins, I checked out what 32 of those cells would cost and it came to a bit over $4300.00...ouch! Then I'd need a Sol-Ark, wiring, BMS, and a second job... Think I'll just keep watching the prices and pray they go down in the near future. Keep me posted and I'll do the same. Oh, I was going to ask where you got the Sol-Ark price comparison and where you plan on buying the unit from? I found a store in St. George, UT that is supposed to be a dealer, but so far, they are slow to respond to inquiries and I don't know if they actually have any to sell. I hope to hear back from them tomorrow. Maybe, when your ready, we can make a deal on buy two, in hopes that we get a better price.

Yeah check out some of the battery threads here, I think others have been able to do better than the seller I went with.

That particular Sol-Ark screen shot above I just grabbed from Practical Preppers website (with link right above it), so those are their costs.

Sol-Ark may offer volume discounts for the general public, I know on our agricultural coop, we had 10 shareholders each buy one as a group buy, and they gave us some kind of discount, and they all came on a pallet in one shipment. I never made it in on our first batch though, as I didn't have funds right at that time due to many other expenditures in my homestead planning. I can talk to our director and see when he thinks we would have enough people for our next batch of 10, and how much they are based on a 10 unit group buy. We might be able to get anyone in on it, I don't know for sure what kind of terms they managed to work out with Sol-Ark on that deal.

 

[Nemaha]

Yeah, I bought my 16x Trina 400w panels from SanTan Solar in AZ as they were on sale for $180 panel (960 lbs shipped on a pallet), best bang for the buck I thought. My end plan is to get a Sol-Ark 12k all-in-one inverter as these are the only ones on the market which can be ordered as EMP-hardened (saving more money to afford it), but to get me through this Winter on DC-only power, I bought the Victron 250|100 charge controller (mainly so I can string every 4 panels in series (around 200v open-circuit voltage), while 4 strings of 4 will be paralleled and can charge the 48v battery banks. Bought prefab 8 awg solar cables on Amazon in 5ft, 10ft, and 30ft (with MC4 ends to plug into the panel factory connector and the Eco-Worthy PV combiner panel which has all the string fuses and main DC breaker and surge protection built-in).

As far as Treeline, I stumbled across them just searching Google, was a bit skeptical, but after chatting with him on a contact us message thread for awhile, it became obvious that he was very technical, knows battery stuff very well, and his prices seemed good and the parts like cells and BMS are all tested and balanced, good quality 200a BMS (from Bellhope Technology), and he sent me all of the high quality battery cables and everything. I decided to drop the hammer on the order with fingers crossed, and they eventually came after a couple weeks. Again, the main reason I liked this guy is he offered advanced replacement on warranty stuff, and offer a full 7 year performance warranty ( > 80%) on the battery packs, and even sent me a Treeline baseball cap. I did look up their address on maps.google.com and looks like they're a smaller startup in a business park in Westminster, CO or something. I'm happy with my purchase. I could've easily built a pack like this myself, but decided to go with this just to try it as it was a bit more turn-key.

Now I am just looking into solar mountings lately... Maybe Sinclair Sky-Rack 2.0 or Power Peak, still looking into these, a bit spendy, or I could build one out of wood and Home Depot hardware...

EDIT: The best info on the Sol-Ark inverters I like is from Practical Preppers, Engineer775 on You Tube: https://www.youtube.com/c/PracticalpreppersLLC/videos

He does a lot of Sol-Ark installs.

I've been looking hard at the Treeline LiFePO4 batteries for my new 15kW PV system. Do you have yours installed yet, and if so, what are your early thoughts on performance, etc.? Thanks.

 

[Samsonite801]

I've been looking hard at the Treeline LiFePO4 batteries for my new 15kW PV system. Do you have yours installed yet, and if so, what are your early thoughts on performance, etc.? Thanks.

I have not had a chance to test them out yet. However, he lists the warranty as follows on performance:

"Three years warranty on components and 7 year performance warranty >80% capacity. "


So I believe it was a decent deal on them, the only thing that was a bit frustrating was since then, I learned that clamping batteries with aluminum plates helps to keep cells from potentially bulging and can help them to get longest cycles. But the Treeline packs I got were all stuck together with double-sided foam tape strips. So if I had known about the clamps thing, I would've simply asked Treeline to assemble, test, and disassemble my pack, and not stick the cells together with the tape, because I had to spend hours with Goo-Gone and remove the tape so they are clean cells, and will sit flat together. So before you bought them, I would ping Randy and just tell if if you want them stuck together or if you plan to clamp them, then don't use the tape.

The only other things, I bought mine with the 200a 16s BMS, and they are fine, they look really heavy duty, made by a Chine company called Bellhope Technologies Ltd. I think they are these ones:

116.4US $ |7S 8S 13S 14S 16S 20S 24S li ion or Lifepo4 Battery PCB board with 120A 200A constant current for auto car 48V 72V Battery|Integrated Circuits| - AliExpress

Smarter Shopping, Better Living! Aliexpress.com

www.aliexpress.com

锂电池保护板_电动车保护板_园林工具无刷控制器_无锡百虹科技有限公司

无锡百虹科技有限公司是一家研发，生产，销售动力锂电池保护板,电动车保护板,园林工具无刷控制器及充电器解决方案为一体的高科技企业，本公司本着人才，追求品质，正道经营，共存共赢的企业宗旨。

www.bellhope.com

They seem good enough for a basic high current BMS, I have 2 of them, 16s for each of 2 battery banks (32 cells total), which I will parallel together. The only thing is, these are un-managed BMS's so no bluetooth smartphone app to do cell level monitoring.

So I am adding in a set of active balancers which offer a bluetooth smartphone app function, where I can at least get cell level voltage monitoring (I'm the type which likes to be able to login and check up on them if I want to once in awhile):

Li-ion Lipo Lifepo4 LTO Battery Active Equalizer 2S-24S BMS APP 2A Balancer NEW | eBay

Find many great new & used options and get the best deals for Li-ion Lipo Lifepo4 LTO Battery Active Equalizer 2S-24S BMS APP 2A Balancer NEW at the best online prices at eBay! Free shipping for many products!

www.ebay.com

Just to note, the Treeline 200a Bellhope BMS do have passive balancing on discharge, so for me, I basically thought the enhancement to active balancer is just a bell/whistle more to give me cell level app monitoring of voltages, since the Bellhope are a 'dumb' BMS...

I am happy with the purchase I suppose, since he does offer advance replacement so if a cell goes bad he can ship replacements right away. My next battery bank I'm building for my RV is a 12v, 4s2p (8 cells), w/ 2x Overkill 120a BMS. Buying raw cells from China cuts the cost in half. (but I am still waiting to receive my shipment on those since Oct 23rd, as it's super slow). I got the Overkill BMS's though (as they are sold in US), they look good offer app level smartphone BMS management, can adjust BMS parameters, etc. They only sell those up to 120a though.

So I've learned some things here, not saying any way is better than the other, I guess it depends on your goals, what you want to spend, how soon you need the solution, etc... Treeline did ship these packs pretty fast though.

Anyways, here is a picture of the Treeline cells (I have all the bus bars off, and nothing connected), they just look like a lot of the EVE-style copys or whatever, or maybe these are EVE, I have no idea where they came from, and those are the BMS's down in the bottom right corner:

 

[JoeHam]

I believe those are Lishen.

See the picture in post #7 here:

EVE or LISHEN

Hello, I am about to buy 280ah cells, but I can't decide if it would be better to buy EVE or LISHEN, from everything I have read in the forum it seems that EVE is the king of purchases here, but there are also people who have bought LISHEN and there are no negative comments about them, the...

diysolarforum.com

 

[Samsonite801]

I believe those are Lishen.

See the picture in post #7 here:

EVE or LISHEN

Hello, I am about to buy 280ah cells, but I can't decide if it would be better to buy EVE or LISHEN, from everything I have read in the forum it seems that EVE is the king of purchases here, but there are also people who have bought LISHEN and there are no negative comments about them, the...

diysolarforum.com

Actually, mine look more like the EVE ones on the right (with the 'lens' shape around the terminals):



And mine were advertised as 280ah from the seller.



REFERENCE:

 

[JoeHam]

Oops. That’s what I meant to say. A picture is worth more than.........

 

[Skysthelimit]

You're getting some good advice here. The 100 watt panels are really not suitable and buying stuff before you have a system design is a sure fire way to waste money and make an underperforming system. EMP hardening is a fantasy, at least in the apocalypse sense. Too many wires and whatnot that will induce voltages.

Good to see someone mention considering FLA batteries. While I would love to go lithium I simply couldn't afford it. I got 10 years out of my last bank of FLA's and no way would lithium be cheaper per year. I would say that the idea of having three days of power storage is an outdated notion. I simply charge every day, if the sun isn't cutting it I fire up the genny. This limits the DoD and makes FLA's last much longer.

I'm curious to know why the 100 watt panels aren't suitable? 100 or 200 watt, what's the difference? In fact, if you have a 200 watt panel that is partly shaded by clouds, isn't the same as having 2 x 100 watt panels and having one in the shade? Please excuse my ignorance but I'm still learning about this stuff.

 

[Skysthelimit]

Actually, mine look more like the EVE ones on the right (with the 'lens' shape around the terminals):

View attachment 28659

And mine were advertised as 280ah from the seller.



REFERENCE:
View attachment 28660

Just checking in to see how the 48v system is progressing and to see if you ever got the additional cells for your RV build or the SolArk?

 

[Hedges]

I'm curious to know why the 100 watt panels aren't suitable? 100 or 200 watt, what's the difference? In fact, if you have a 200 watt panel that is partly shaded by clouds, isn't the same as having 2 x 100 watt panels and having one in the shade? Please excuse my ignorance but I'm still learning about this stuff.

Because a 100W panel may be sold for $100 or $200, but we can buy a 250W panel for as little as $37. (A bit more if you want fine, clean PV panels)
Unless 100W is all that fits and you can get some used ones cheap.

For some applications a small panel and PWM SCC is the way to go. But if you want lots of Wh and operation over seasons and temperature range, an MPPT charge controller and larger, higher series string of voltage panels will deliver more. The voltage/current tradeoff of MPPT lets it deal with variations in temperature, illumination, and partial shading.

 

[Samsonite801]

Just checking in to see how the 48v system is progressing and to see if you ever got the additional cells for your RV build or the SolArk?

Not really any progress lately, for the holiday had to go run to Michigan and helping a family member install a Mr Cool 4-zone HVAC at his house as it's too cold here. So my life as a solar enthusiast is like on total hold right now, I'm more like a wannabe HVAC guy for the last couple weeks hehe...

However, I DID get my 8x cells for the 12v system from China before I left, they look like the exact same brand as whatever my existing cells for the 48v system are. I tested the volts on them and they look very close, haven't done much with them yet since I had to tend to this other project...

I did decide too that a Sol-Ark will come later, for now I bought 2x MPP LV6548 to get me by for the next couple years or so until I can find it in better budget to upgrade to Sol-Ark. I need to save money for structures before I mess with too fancy of an inverter for now

 

[boondox]

I'm curious to know why the 100 watt panels aren't suitable? 100 or 200 watt, what's the difference? In fact, if you have a 200 watt panel that is partly shaded by clouds, isn't the same as having 2 x 100 watt panels and having one in the shade? Please excuse my ignorance but I'm still learning about this stuff.

Being small, you need a lot of them. This means more connections, more wire, more racking to mount them and so on. This translates into higher cost per watt, not to mention more time and effort. Not to say they won't work but I think most would be served better by larger panels.

 

[Skysthelimit]

Because a 100W panel may be sold for $100 or $200, but we can buy a 250W panel for as little as $37. (A bit more if you want fine, clean PV panels)
Unless 100W is all that fits and you can get some used ones cheap.

For some applications a small panel and PWM SCC is the way to go. But if you want lots of Wh and operation over seasons and temperature range, an MPPT charge controller and larger, higher series string of voltage panels will deliver more. The voltage/current tradeoff of MPPT lets it deal with variations in temperature, illumination, and partial shading.

I bought 10 x 100 watt panels from Costco at $99 each and 30 x 100 panels from Amazon at about $80 each. Had I know about the $37 panels, I would certainly have looked into them. Please tell me where or share a link to this awesome deal. Thanks, in advance.

 

[Skysthelimit]

Being small, you need a lot of them. This means more connections, more wire, more racking to mount them and so on. This translates into higher cost per watt, not to mention more time and effort. Not to say they won't work but I think most would be served better by larger panels.

I appreciate your response. Yes, I understand about the extra wiring, etc. To be honest, I never thought about that until you mentioned it. Hopefully, the other member who also posted about my choice of 100 watt panels will share the info he has on panels in the 200+ watt range for as little as $37, which is difficult to imagine. Do you have any suggestions as to where I can buy good quality panels?

 

[Hedges]

I bought 10 x 100 watt panels from Costco at $99 each and 30 x 100 panels from Amazon at about $80 each. Had I know about the $37 panels, I would certainly have looked into them. Please tell me where or share a link to this awesome deal. Thanks, in advance.

Solar Panels | SanTan Solar

store.santansolar.com

The cheapest have had UL labels stripped off, not for use on a house.
A number of forum members have bought the 250W inexpensive models.
Others select one that's a bit higher price per watt.

A few other resellers around the nation have similar offerings. Also found on eBay and Craigslist.
I found SanTan by an eBay posting.