Need some advise regarding my first build.

[Johnyguy]

Hello Guys.

I like to build a battery backup made out of 8 EVE 280Ah cells I have ordered the batteries already ,
I will have the batteries and all the electronics placed in the closet next to the living room the solar panels will be placed at the balcony it is a long balcony so i was thinking 2 panel at each end or depends how much I need to keep the batteries full , im in the renovation of this apt so i will able to run a 8 AWG cable (20 feet) or whatever AWG I need in the ceiling from the balcony to the closet to carry the power across also was thinking to use a 1" aluminum conduit for the cable for safety if need.

My initial idea was to build a 24V battery bank so I thought I buy (I did) 8 of EVE 3.2v cells in series will make 25.6V but now I am thinking maybe I could connect the 4 in series so i have two sets of 12 volt and that connect them in parallel to get the 24V what is the best way to get the most out of them??

What I like to power with this batteries if the power goes out power the fridge I will have a wire to the fridge just from the inverter in case I need . would i be able to run it permanently from the batteries ?

Run a wire to the living room behind the the TV and power my TV and stereo system permanently.?

And run the led lights i have installed upstairs in the bedrooms permanently or temporary?

Is this enough battery how much do i need?
My balcony is facing south so i have a lot of sun exposure all day long (I am in Florida)
But because of the management I don't or can't fill my balcony with solar panels for obvious reasons but i would get away with 4 I think....

Alot of questions...

Any advice would be appreciated!!

Thank you

John

 

[MisterSandals]

Is this enough battery how much do i need?

You need to do an energy audit and figure out how many watt hours the things you listed use each day.
You will need solar panels about 1/5 your watt hour number.
You will need batteries to store all the power outside the 5 quality charging hours each day.
It’s all pretty easy to add up once you get your daily watt hours.

There are links to a couple energy audit tools in my signature.

 

[time2roll]

My initial idea was to build a 24V battery bank so I thought I buy (I did) 8 of EVE 3.2v cells in series will make 25.6V but now I am thinking maybe I could connect the 4 in series so i have two sets of 12 volt and that connect them in parallel to get the 24V what is the best way to get the most out of them??

Parallel batteries add amps, not volts. Series batteries add volts, not amps. Either way it is the same amount of energy.

If going 24 volts it is best to have a single 24v battery (8 cells in series) with a single BMS to keep the cells balanced.

The battery will power an inverter to provide 120vac. Use an extension cord to plug the fridge etc into the inverter when needed.

 

[Johnyguy]

You need to do an energy audit and figure out how many watt hours the things you listed use each day.
You will need solar panels about 1/5 your watt hour number.
You will need batteries to store all the power outside the 5 quality charging hours each day.
It’s all pretty easy to add up once you get your daily watt hours.

There are links to a couple energy audit tools in my signature.

thank you for the reply
what about connecting the batteries the way i described it ?

 

[Johnyguy]

Parallel batteries add amps, not volts. Series batteries add volts, not amps. Either way it is the same amount of energy.

If going 24 volts it is best to have a single 24v battery (8 cells in series) with a single BMS to keep the cells balanced.

The battery will power an inverter to provide 120vac. Use an extension cord to plug the fridge etc into the inverter when needed.

Hi
yes i will have the 8 cells on the way ....
i will have the option to run wires just for the fridge tv etc ...
I will need 24 volt panels correct?
If i have 5 good hours of sun everyday how many panels would i need ?
I was thinking to connect the panels in parallel because the sun is moving so it would hit 2 in the morning than move over to the other 2 is it a good idea?

 

[time2roll]

One panel is fine for emergency use or use a plug in charger periodically.

To run the fridge full time I would guess 600 to 1000+ watts of panels could be needed. Post the energy consumption of the fridge for a calculation.

 

[Johnyguy]

Parallel batteries add amps, not volts. Series batteries add volts, not amps. Either way it is the same amount of energy.

If going 24 volts it is best to have a single 24v battery (8 cells in series) with a single BMS to keep the cells balanced.

The battery will power an inverter to provide 120vac. Use an extension cord to plug the fridge etc into the inverter when needed.

would 8 AWG cable be enough to run it 20 feet to the charge controller and should i put it into a metal conduit for safety in the ceiling ?

 

[MisterSandals]

what about connecting the batteries the way i described it ?

I like a single BMS to manage and that means an 8S battery.

The biggest gotcha is if you need to pull more amps than your BMS can deliver.

If i have 5 good hours of sun everyday how many panels would i need ?

You REALLY should do an energy audit to figure out your needs. And it’s more than just arriving at a number, you will learn more in this step than any other.

 

[time2roll]

I doubt more than #10 is needed to connect the panels to the solar controller. Depends on the configuration and wattage. Controller should be mounted close to the battery. May need heavier wire to connect the controller to the battery.

Best to know what Equipment is being connected. Then the wire is easy.

Yes all building codes need to be followed.

 

[Johnyguy]

One panel is fine for emergency use or use a plug in charger periodically.

To run the fridge full time I would guess 600 to 1000+ watts of panels could be needed. Post the energy consumption of the fridge for a calculation.

659 kWh yearly of course for the fridge I think i like to take advantage of the sun if I build this and use it for the Fridge permanently and for upstairs lights 4 led total 60 watts.

 

[MisterSandals]

To run the fridge full time I would guess 600 to 1000+ watts of panels could be needed. Post the energy consumption of the fridge for a calculation.

Just messing with numbers…
80W x 24h = 1920W
1920W / .85 inverter loss = 2259Wh
2259Wh / 5h = 452 W solar panels operating at 100% efficiency.

Storage for 19h non-peak solar:
2259W x (19/24) = 1788Wh from battery (just the fridge still)
1788Wh / 25.6V battery = 70Ah

All rough numbers, I used my fridge consumption.

 

[Johnyguy]

Just messing with numbers…
80W x 24h = 1920W
1920W / .85 inverter loss = 2259Wh
2259Wh / 5h = 452 W solar panels operating at 100% efficiency.

Storage for 19h non-peak solar:
2259W x (19/24) = 1788Wh from battery (just the fridge still)
1788Wh / 25.6V battery = 70Ah

All rough numbers, I used my fridge consumption.

I am not good with spreadsheets
So i would need 70 Ah for the fridge in a perfect conditions ?
so the eve 280Ah if i get half out of it it would work?
and also using 4 panels 200 W each would help right?
more solar not a bad thing right

 

[MisterSandals]

also using 4 panels 200 W each would help right?

Have you checked Craigslist for big cheap panels?

If you got 3 or 4 big panels,
900-1000W, you might be ok.
280Ah @ 25.6 V is a great battery (I have 2 of those on deck).

With 280Ah x 25.6V = 7168Wh

To just recharge, with nothing running, not even the fridge, you would need:
7168Wh / 5h = 1433W of panels to recharge in a day under perfect conditions an 100% efficiency. If you matched array to battery, for single day recharge, with loads, you’d be over 2000W of solar.

But if you calculate your usage (same as I did for fridge), you can get a realistic number.

 

[Johnyguy]

Have you checked Craigslist for big cheap panels?

If you got 3 or 4 big panels,
900-1000W, you might be ok.
280Ah @ 25.6 V is a great battery (I have 2 of those on deck).

With 280Ah x 25.6V = 7168Wh

To just recharge, with nothing running, not even the fridge, you would need:
7168Wh / 5h = 1433W of panels to recharge in a day under perfect conditions an 100% efficiency. If you matched array to battery, for single day recharge, with loads, you’d be over 2000W of solar.

But if you calculate your usage (same as I did for fridge), you can get a realistic number.

to use the fridge on a daily basis i would need more solar but i don't have the space for it so the to use the fridge it is only for a emergency situation ... but i can use it for the lights upstairs 15 W each x 4 60W 4 hours a day , and use it for computer smaller loads so the batteries have some usage not just sitting , if i would get more cells than i need to charge them so that would make things worst ... just thinking loud ... this is the limitations i have but it is ok i guess....

 

[time2roll]

Yes. Nothing wrong with adjusting the power usage based upon the solar yield to power what you can.
If conditions are expected to possibly create an outage.... let the battery fill 100% to prepare.

 

[MisterSandals]

can you rec

Can you recommend a charger for this batteries?

Budget?
Quality/reliability level?
How quickly do you want to charge? Or, what is the wattage of your array?

Any other constraints or desired features?

Good discussion here we just had:

MPPT Charge Controller

Is it possible use a MPPT charge controller and have my panels hooked in series to make 24V and keep my batteries at 12V?

diysolarforum.com

 

[Johnyguy]

Budget?
Quality/reliability level?
How quickly do you want to charge? Or, what is the wattage of your array?

Any other constraints or desired features?

Good discussion here we just had:

MPPT Charge Controller

Is it possible use a MPPT charge controller and have my panels hooked in series to make 24V and keep my batteries at 12V?

diysolarforum.com

this 8 cells i purchased to charge them up time to time 280Ah something decent does not damage the battery no need super fast ... any recommendation ?
thanks!!

 

[MisterSandals]

For what array size? 800W?

800W / 25.6V = 32A max.

I have one of these, Cadillac solution (5 yr warranty, bluetooth configuration, monitor and firmware updates…awesome):

https://www.amazon.com/dp/B073ZJ3L13

If you had 400W solar:

Amazon.com: Victron Energy SmartSolar MPPT 75V 15 amp 12/24-Volt Solar Charge Controller (Bluetooth): Industrial & Scientific

Buy Victron Energy SmartSolar MPPT 75V 15 amp 12/24-Volt Solar Charge Controller (Bluetooth): Energy Controllers - Amazon.com ✓ FREE DELIVERY possible on eligible purchases

www.amazon.com

And get the model with Bluetooth. (You’re welcome.)

 

[Johnyguy]

For what array size? 800W?

800W / 25.6V = 32A max.

I have one of these, Cadillac solution (5 yr warranty, bluetooth configuration, monitor and firmware updates…awesome):

https://www.amazon.com/dp/B073ZJ3L13

If you had 400W solar:

Amazon.com: Victron Energy SmartSolar MPPT 75V 15 amp 12/24-Volt Solar Charge Controller (Bluetooth): Industrial & Scientific

Buy Victron Energy SmartSolar MPPT 75V 15 amp 12/24-Volt Solar Charge Controller (Bluetooth): Energy Controllers - Amazon.com ✓ FREE DELIVERY possible on eligible purchases

www.amazon.com

And get the model with Bluetooth. (You’re welcome.)

hi yes i need that too but i meant to charge the batteries from the grid when i get them...
i see many people using a power supply is that a better way to do it i guess you would have more control over it
any you would recommend or just a stand alone charger?

 

[MisterSandals]

any you would recommend or just a stand alone charger?

I only have solar chargers, nothing from grid.