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Car/Motorcycle lithium batteries on solar system

Edas

New Member
Joined
Feb 22, 2021
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5
Hi everyone,

I'm really a beginner in this forum and in Solar subjects.
I'm about to buy and install my first solar kit, but I would like to buy different batteries like for motorcycles or cars, since they are a lot more cheaper than the ones sold by solar companies. I have a couple of questions that I would like to have your advice/comments:

1. Is there any problem to connect a lithium motorcycle battery (LiFePo4,12,8V, 20Ah/256Wh) like the one below instead of the lithum batteries usually sold by Solar companies?
1614015877656.png

2. Should I have anything else in consideration when buying LiOn batteries like BMS (battery management system)? What happens if I don't have a battery with BMS?

3. I'm about to buy and install the system in the picture below. This inverter is prepared to connect lithium batteries, but I don't know exactly where should I install them. I marked in red in the diagram, is it correct? If so, should I use any protection (fuses, for eg.)? Where?

1614045847055.png
I would really appreciate your help.
Thanks in advance.
 
What does.
Solar panels 4x450Kw mean?
How many panels?
Panels are measured with Watts.
How big are the panels?

What is the price of that 20Ah motorcycle battery?
Sales link?

The battery connects to the battery terminals on your Inverter.
 
Vehicle starting batteries will fail quickly if you deep cycle them.
But if used in a PV system which only powers loads while the sun is providing enough power, the batteries would give the surge needed to start a motor like an air conditioner.

As Forbisher said, battery has to go to battery terminal of the inverter. Reason is, direct connect to PV panels would drive voltage too high and rupture the batteries, venting their electrolyte. We always use a charge controller which must have its parameters set to match the battery.

The inverter you show appears to use a high voltage (400V) battery, "LG-RESU battery connected: 350–450 V"
So no, this inverter can't use the pair of 12V batteries you're considering.

file:///C:/Users/the_f/AppData/Local/Temp/SUN2000-2-5KTL-L1_UserManual.pdf

"The SUN2000 can connect to LG-RESU batteries (LG RESU7H and RESU10H)"

At least one of those (RESU10H) has been recalled for fires in the US.


Probably, this inverter only works with LG RESU or possibly other batteries which have a BMS that uses compatible communications.
You will need to select all equipment to work together.

Some other brands people here use don't have communication links, so almost anything can be mixed and matched, but then there are issues having the inverter or charge controller adjusted correctly so BMS doesn't have to disconnect for protection.
 
What does.
Solar panels 4x450Kw mean?
How many panels?
Panels are measured with Watts.
How big are the panels?

What is the price of that 20Ah motorcycle battery?
Sales link?

The battery connects to the battery terminals on your Inverter.
it is a mistake, obviously it's not kW but W. It means I expect to install 4 panels of 450 w each.

The battery I put is only an example and it costs 155€ (https://innpo.pt/baterias-recarrega...ah-innpo-baterias-recarregaveis-de-litio.html)

When you say "The battery connects to the battery terminals on your Inverter.", it means the inverter has a specific input for batteries? I though it whoul be the same input for panels and batteries, since both use 12V DC.
 
Vehicle starting batteries will fail quickly if you deep cycle them.
But if used in a PV system which only powers loads while the sun is providing enough power, the batteries would give the surge needed to start a motor like an air conditioner.

As Forbisher said, battery has to go to battery terminal of the inverter. Reason is, direct connect to PV panels would drive voltage too high and rupture the batteries, venting their electrolyte. We always use a charge controller which must have its parameters set to match the battery.
Good explanation. Thanks.

The inverter you show appears to use a high voltage (400V) battery, "LG-RESU battery connected: 350–450 V"
So no, this inverter can't use the pair of 12V batteries you're considering.

I thought batteries would charge at 12V DC like the panels. Now I understand that panels drive voltage is too high and the inverter input is prepared. I've searched several inverters but they always use an high voltage range for batteries charge, the minimum I found is 100V which is not compatible with 12V batteries.

"The SUN2000 can connect to LG-RESU batteries (LG RESU7H and RESU10H)"

At least one of those (RESU10H) has been recalled for fires in the US.


Probably, this inverter only works with LG RESU or possibly other batteries which have a BMS that uses compatible communications.
You will need to select all equipment to work together.

Some other brands people here use don't have communication links, so almost anything can be mixed and matched, but then there are issues having the inverter or charge controller adjusted correctly so BMS doesn't have to disconnect for protection.
The idea is to buy cheaper batteries because those LG are too expensive for my budget. Any recommendation?

Thanks for the good help.
 
A 20 amp hour battery is tiny, compared to what most people use for a solar system. There are some systems that don't use any batteries, but if you want to have power when the sun isn't shining you need to be grid tied, or have a generator, or have batteries to store the power you make during the day.

The first question you need to answer is, "what are you going to run off of this system?" That is what determines how large your system needs to be.
 
The idea is to buy cheaper batteries because those LG are too expensive for my budget. Any recommendation?

Don't use that inverter.

There are inverters and battery chargers for 12V, 24V, 48V batteries.
There are hybrids (similar to the inverter you considered) which connect to PV and an inexpensive battery.

Here's just one of many that some people here use or discuss. Pick a brand or model and try the search function on this site to learn about it.

 
A 20 amp hour battery is tiny, compared to what most people use for a solar system. There are some systems that don't use any batteries, but if you want to have power when the sun isn't shining you need to be grid tied, or have a generator, or have batteries to store the power you make during the day.

The first question you need to answer is, "what are you going to run off of this system?" That is what determines how large your system needs to be.
The system will be grid tied. The objective is to add additional amps to the power contracted to the electrical company (higher contrated power, more expensive it will be the bill in the end of the month). My contract has 3,45 kVA (15A @230V AC) and I will need to have a couple of equipment working at the same time, a consumption like 25A. The batteries are necessary because, besides the place being very sunny almost all the year, the major consumption is in the night period.
 
The system will be grid tied. The objective is to add additional amps to the power contracted to the electrical company (higher contrated power, more expensive it will be the bill in the end of the month). My contract has 3,45 kVA (15A @230V AC) and I will need to have a couple of equipment working at the same time, a consumption like 25A. The batteries are necessary because, besides the place being very sunny almost all the year, the major consumption is in the night period.


With SMA Sunny Island (my picture), I could set grid input to 15A max. If demand was higher, the inverter would produce power from battery. Other times it would recharge battery.

You would need enough battery for the nighttime consumption.

With Sunny Boy (connected to output of Sunny Island), PV is converted to AC. It also provides power to loads. If more than needed either for loads or recharging battery, it back-feeds the grid. That is good if you have "net metering", are only charged for net consumption considering both consumption and production.

I think I could also configure Sunny Island to never backfeed, disconnect and run off-grid whenever PV exceeds needed power.

Some other brands will do the same. I'm not sure with the MPP but probably some of their models do and those would be more economical than SMA.
 
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