diy solar

diy solar

Looking for advice on what size components.

ppzzus

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I just got my 280ah AliExpress cells in the mail today. They look immaculate and Im in the process of bottom balancing them now. I'm incorporating them into my short bus skoolie build. I had some questions on fb and they pointed me here. I have 8 cells and want to build a 24v system. My power requirements are pretty low (will likely never exceed 400W) but I wanted a large reserve. I was going to buy a 24v 250a 8s Daly BMS, but is this the right size I need? I haven't purchased a charge controller but wanted to use a smart solar system. I guess I'm a little confused about sizing the panels/BMS/charge controller so they all agree with each other.

I built wiring panels on industrial washing machines for a while so I'm fairly competent with wiring but sizing these 3 items correctly is throwing me for a loop. My job was mostly just following schematics/blue prints. Any advice would be appreciated!
 
If you like to see the data on your future system- (watts being generated by solar, used by loads, battery status - all in one place) look at Victron. It costs more, but is nice and the different items can pass the data so you can see it. Look up YouTube’s for a CCGX or Cerbo.(The CCGX is old - but the data screen is the same).

If that info has value! Go all victron-but it will cost a bit more.

Will you want a microwave or convention oven in your bus? (Those are the largest loads in my MotorHome). What 120v items do you want to run? For systems you need to start with the largest items?
 
If you like to see the data on your future system- (watts being generated by solar, used by loads, battery status - all in one place) look at Victron. It costs more, but is nice and the different items can pass the data so you can see it. Look up YouTube’s for a CCGX or Cerbo.(The CCGX is old - but the data screen is the same).

If that info has value! Go all victron-but it will cost a bit more.

Will you want a microwave or convention oven in your bus? (Those are the largest loads in my MotorHome). What 120v items do you want to run? For systems you need to start with the largest items?
Really the only thing I'm running is a PC for work and one for some light video editing. I have a propane burner installed. It's really a basic setup. I won't be living in it full time but I like the idea of roughing it a bit. Other than the PC's it's just a router and small devices like cell phones cameras etc.
 
250A @ 24v is way overkill for your stated system, but it would allow you a lot of overhead/room to grow.

250A * 24v = 6000W
Compare that to your expected load of 400W

You do want to oversize the BMS to some degree, to account for 'optimistic' marketing/specs on cheap products, and any unforeseen loads or future growth of your system, but still 250A is huge overkill if you only expect 400W max.

You want to size the BMS for the max expected or designed for current in and out. And then add on 25% to 100% overhead to account for the above.

In terms of how it fits with the rest of your system, the BMS should be rated to handle at least the inverters max and the solar charge controller's max.
 
Is there anything specific I need to look for in terms of panels? I was going to go with 800-1200 watts for panels.
 
I saw lots of posts with problems/quirks with the Daly BMS(s) so bought a JBD (some refer them as Overkill)
For your use an 8s/100a would work well. You could draw 2000w or about 80a (roughly)
If at some point you expand your battery bank, a pair of batteries in parallel will split the load allowing a draw double the original 2000w / 80a

JBD 8s/100a BMS
from Current Connected : https://www.currentconnected.com/product/jbd/
This is where I bought mine along with the Y leads for it. Great service.

Overkill offers more options for wiring
https://overkillsolar.com/product/bms-100a-8s-lifepo4/
..as of this time there is only one left in stock

Got to agree with Rocketman,
a Victron SCC is the way to go. You'll pay a premium but after I upgraded to a Victron 100/50 Bluetooth I swear by them.

The choice of size of a SCC depends on your panels and how you want to configure them. The primary concern is voltage in.
In my case I have (8) 195w panels wired 2s4p.
The VoC of the panels is around 20v but calculated for low temp (-40) to 27v.
I could go to series strings of 3 panels - plenty of leeway to expand.

If you buy larger panels be aware of the VoC and chose a SCC that can handle the higher voltages.

I'd also recommend planning on expanding as you buy components. Once bitten by the solar bug it's hard not to think about "MORE".
More battery for prolonged use during rainy/cloudy weather
More panels for collecting some power on those cloudy days and power to burn on good days
(in my case an A/C unit in a shed during the dog days of summer)
 
I saw lots of posts with problems/quirks with the Daly BMS(s) so bought a JBD (some refer them as Overkill)
For your use an 8s/100a would work well. You could draw 2000w or about 80a (roughly)
If at some point you expand your battery bank, a pair of batteries in parallel will split the load allowing a draw double the original 2000w / 80a

JBD 8s/100a BMS
from Current Connected : https://www.currentconnected.com/product/jbd/
This is where I bought mine along with the Y leads for it. Great service.

Overkill offers more options for wiring
https://overkillsolar.com/product/bms-100a-8s-lifepo4/
..as of this time there is only one left in stock

Got to agree with Rocketman,
a Victron SCC is the way to go. You'll pay a premium but after I upgraded to a Victron 100/50 Bluetooth I swear by them.

The choice of size of a SCC depends on your panels and how you want to configure them. The primary concern is voltage in.
In my case I have (8) 195w panels wired 2s4p.
The VoC of the panels is around 20v but calculated for low temp (-40) to 27v.
I could go to series strings of 3 panels - plenty of leeway to expand.

If you buy larger panels be aware of the VoC and chose a SCC that can handle the higher voltages.

I'd also recommend planning on expanding as you buy components. Once bitten by the solar bug it's hard not to think about "MORE".
More battery for prolonged use during rainy/cloudy weather
More panels for collecting some power on those cloudy days and power to burn on good days
(in my case an A/C unit in a shed during the dog days of summer)
Ended up scoring that jbd BMS. I hope the don't use FedEx ?. Now I need to work with the local solar place on panels. Then I'll be able to get my charge controller.
 
Ended up scoring that jbd BMS. I hope the don't use FedEx ?. Now I need to work with the local solar place on panels. Then I'll be able to get my charge controller.
I know Current Connected ships UPS. I bought 2 from them and it took about 3/4 days - cross country
Don't know about Overkill

A number of members have purchased good used panels.
If you're anywhere near and can pick them up to save shipping expenses they are well worth the price.

Two frequently mentioned sellers:

SanTan Solar
https://santansolar.com/

SIGNATURE SOLAR
https://shop.signaturesolar.us/collections/solar-panels
 
I know Current Connected ships UPS. I bought 2 from them and it took about 3/4 days - cross country
Don't know about Overkill

A number of members have purchased good used panels.
If you're anywhere near and can pick them up to save shipping expenses they are well worth the price.

Two frequently mentioned sellers:

SanTan Solar
https://santansolar.com/

SIGNATURE SOLAR
https://shop.signaturesolar.us/collections/solar-panels
Unfortunately those are quite a ways away. I've been working with a company called Mann solar. They are kind of a paint to reach sometimes though.
 
For panels on a rig, size usually wins. I used four 200watt hightec panels from continuous resources. They had them shipped from the manufacturer directly to me. (Then I added two more later). These went on my MotorHome. At about $200 each they were expensive, but they fit the space very well.
When I was helping my father put some panels on his 5th wheel, he had LOT of roof space, so we put two used 250watt Suntan solar panels. They are much bigger (not as efficient in terms of watts/square meter), but he has so much space cheaper dollars wins (and 500w for him is plenty)

A lot depends on your roof space.
 
Agreed, a lot of time and focus is spent asking about brand, efficiency, etc, but for mobile or marine, the tetris/origami specific to your situation and your roof can have a much larger impact, on how many Watts of solar you can squeeze in.
 
Luckily if got a pretty large roof with a ton of space. So really sky is the limit as far as how many panels I can fit.
 
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I have a call setup with the local solar people today so I should get more info on the panels and charge controller later.
 
Can anyone recommend a battery charger for top balancing? I believe it was 3.65 volts?
 
Can anyone recommend a battery charger for top balancing? I believe it was 3.65 volts?
There is some discussion and some users reviews of a few of the budget friendly options in the Tools section of this website.
RD Riden is one of the popular cheaper options (or it was last time I paid any attention which was about ~8 months ago). Mastech is one of the more popular pricier but higher quality options, possibly overkill/too much $$ if you will only be using it for a single top balance.

Here is one related post, there are others too:
 
There is some discussion and some users reviews of a few of the budget friendly options in the Tools section of this website.
RD Riden is one of the popular cheaper options (or it was last time I paid any attention which was about ~8 months ago). Mastech is one of the more popular pricier but higher quality options, possibly overkill/too much $$ if you will only be using it for a single top balance.

Here is one related post, there are others too:
Thanks I scored one out of there. Went with a cheapish option since I will hopefully only be building one battery bank lol
 
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