Solar Production Exceed Load, Is Battery Used?

[Anteclansing]

Hi,

I am pretty new to DIY Solar and stuff. I'm just trying to look for the answer to this question:

Let's say I have an offgrid solar system with 1kw solar panels and some battery, but I'm pulling only 500w. I understand that I have 500w extra to either charge the batteries if they are not full or if they are full then they will just disappear. But the question I have is if I'm pulling 500w, does this 500w come from the solar panels -> battery -> load or does it come directly from solar panels. Does this use up my battery cycles? Thank you so much if you can help me to clarify this.

 

[zanydroid]

I’ll assume here that you are actually getting more than 500W of production from the panels. It is highly dependent on angle and weather conditions, and the nameplate on solar panels is optimistic.

In this case the batteries will not provide the power; the solar will go straight to the inverter or load.

Now with regard to cycles… the number of cycles on LFP batteries is theoretically high enough that calendar wear is more important to worry about than cycles.

 

[Anteclansing]

Thank you so much for your reply. Yes. Assuming you ACTUALLY get 1000w from the solar panels, not just the rating. So that means as long as I keep my PV production higher than load, the batteries are untouched?

 

[gotbeans]

Hi,

I am pretty new to DIY Solar and stuff. I'm just trying to look for the answer to this question:

Let's say I have an offgrid solar system with 1kw solar panels and some battery, but I'm pulling only 500w. I understand that I have 500w extra to either charge the batteries if they are not full or if they are full then they will just disappear. But the question I have is if I'm pulling 500w, does this 500w come from the solar panels -> battery -> load or does it come directly from solar panels. Does this use up my battery cycles? Thank you so much if you can help me to clarify this.

depends on the charge controller / inverter setup but any ideal setup and hybrid is going to bypass the battery and just convert the solar power directly to your AC power you're using.
batteries are only used if they're needed. If you pull 1000 watts and your solar is only doing 500 watts then 500 watts of solar and 500 watts of battery is going to be used.
If your batteries are charged they're not gonna be touched other than the above scenario

again this depends on charge controller / inverter etc. You can certainly have independent parts that don't do this and always use the battery. That's not optimal though

 

[zanydroid]

Thank you so much for your reply. Yes. Assuming you ACTUALLY get 1000w from the solar panels, not just the rating. So that means as long as I keep my PV production higher than load, the batteries are untouched?

Sure. But that is a probabilities game, dependent on weather and time of year. Battery is in general still needed for most loads to buffer low production.

 

[Anteclansing]

Thanks. I have a hybrid charger/inverter all in one and my batteries are 48v with individual bms. The bms shows the cycles are going up even though according to the data, the number of cycles should not go up that fast if it got by passed. So does that mean I got a bad inverter? I was monitoring the load and production and was conservative not to pull over the production by a lot, but the cycles still go up by the end of the day.

 

[timselectric]

Assuming that you don't live in Antarctica. You're pulling from the battery at night. So you are cycling the battery every day.