New install

[robster]

Hi guys had a new installation a couple of days ago and works great but have a few questions.

The battery discharges to 20% then the grid kicks in, is this to protect the batteries? (Pylontech)

is there a max power charge and discharge rate 3kw/h? Again can that be changed?

can the batteries be charged from the grid and does that effect the batteries?

[SunEagle]

Hello robster and welcome to Solar Panel Talk

How your batteries charge should have been detailed in your proposal. The 20% depth of discharge is also dependent of the chemistry and may effect the life of that system.

[Srrndhound]

The battery discharges to 20% then the grid kicks in, is this to protect the batteries? (Pylontech)

Stopping the discharge before reaching 0% has multiple reasons. As SunEagle noted, you do not want batteries drained to zero as that can harm their life. Also, you do not want to drain them in case there's a grid failure, and you might want to keep some lights on. The grid thus has to kick in at some point as the batteries deplete.

is there a max power charge and discharge rate 3kw/h? Again can that be changed?

That depends on your inverter and the PV capability. It would help to know your system components if you want to discuss more specifically.

can the batteries be charged from the grid and does that effect the batteries?

In my system the batteries can take charge from the grid in the specific case of topping them off prior to a storm. SolarEdge calls it Weather Guard. Other than such occasions I cannot think of many reasons to charge from the grid. That's what the panels are for. Regardless of whether they are charged from the grid or the panels, the batteries don't know or care.

[Ampster]

Hi guys had a new installation a couple of days ago and works great but have a few questions.
.......
can the batteries be charged from the grid and does that effect the batteries?

If you took the investment tax credit on the batteries, charging from the grid more than occasionally could jeopardize that credit.

[robster]

Cheers guys

I've got a sofar 6000es inverter and pylontech batteries. Looks like 20% charge on the batteries gives a 10yr warranty, reducing to 10% is about 7.5years.

I've got an electric car so maybe occasions where want to use off peak grid power to make sure I have some charge in the car if the battery and/or house have consumed it all

[Srrndhound]

I've got a sofar 6000es inverter

Ok, to your original questions, my read of the data sheet confirms that the maximum battery charging power is 3 kW. It also says the charging current is programmable, but that would only serve to reduce the charging power, not increase it.

I've got an electric car so maybe occasions where want to use off peak grid power to make sure I have some charge in the car if the battery and/or house have consumed it all

Yes, that makes sense to try to make sure any use of grid power is during the cheapest cost windows.

[Calsun]

Battery life is defined as XXX charge cycles and going from 50% SOC to 100% or 20% to 100% are both charge cycles. Depending on the type of battery the safe discharge level can be 50% as with common flooded lead acid to 10% with lithium-phophate batteries. Some lithium batteries need a special jumping to reactivate them if they are discharged below 10% SOC.

We have net metering so the charging is from the grid and done at off-peak hours which does not interfere with our normal use of electical devices in the house. We have a 100-amp panel and so we are limited on what we can operate at the same time.

[Ampster]

Battery life is defined as XXX charge cycles and going from 50% SOC to 100% or 20% to 100% are both charge cycles. .......

That may be true for Pb batteries but my EV manufacturer defines a cycle as a full cycle so I get twice as many cycles only using 50 percent of the capacity. Even then the battery may only be reduced to 75-80 percent capacity so it still would have a lot more life than a dead Pb battery. My stationary pack may only have 3000 cycles but since I only use 25 percent of it. it may well out live me.