Grid Off Standalone wind-solar hybrid battery charging system

Thameraladnan

Hello there,

I am interested in understanding the behavior of my little 2kW wind and 900W solar PV system for charging double string of 48V Battery Bank!

firstly, I am curious weather there is a formula to calculate the battery capacity of a specific system despite the end-load size.

secondly, my wind turbine is 2kW and it never gives even 1.5 kW! I think this is due to the size of battery, I believe it would give more power if I add more batteries in parallel to maximize the charging current from the PMSG used in the WEC system.   

looking forward seeing from you experts.

best wishes.

mike95490

I am curious weather there is a formula to calculate the battery capacity of a specific system despite the end-load size.

Huh ?  The end load for 24hours is what sets the required size of the battery.  Too large, and you waste money, too small and you deplete the battery and loose power.

my wind turbine is 2kW and it never gives even 1.5 kW! I think this is due to the size of battery,

No, it's because wind turbines are sold with lots of hype and most are improperly installed.  Your battery size has nothing to do with the about of power the turbine can deliver.  (well, too small of battery would burn up, but that's pretty rare.)

Thameraladnan

Huh ?  The end load for 24hours is what sets the required size of the battery.  Too large, and you waste money, too small and you deplete the battery and loose power.

great to have you mike95490 in this post.

I would again work it out starting from the nature of the load I want to supply and then I can choose the right wind turbine size. but I have to remember the wind regime in the site.

Your battery size has nothing to do with the about of power the turbine can deliver.

the reason I am thinking that way is the idea of having a 5kW diesel generator supplying a house having total power of 3kW of appliances.
the generator will supply whatever the load need as long as the load is within its rated power. but the diesel generator will not provide its max power when the load is less than it. does it ?

(well, too small of battery would burn up, but that's pretty rare.)

that's right when there is no charging controller. But my system has a controller with a dump load to dump excess power from the wind when the batteries are satisfied.

mcgivor

 @Thameraladnan said:  The reason I am thinking that way is the idea of having a 5kW diesel generator supplying a house having total power of 3kW of appliances.

the generator will supply whatever the load need as long as the load is within its rated power. but the diesel generator will not provide its max power when the load is less than it. does it ?

The generator has a regulator, so correct when there is no load the current will drop off and the throttle will back off the fuel to the injection system to reduce power output. Say for example the load was 3Kw but the fuel delivery was fixed to that load, when the load is  suddenly disconnected, the engine would speed up to maximum revolutions and potentially damage could result. This is how the wind turbine behaves, the reason a dump load, or a brake,  is required, to prevent runaway, you can't throttle the wind back to suit the load. The size of the battery will determine the transition to the dump load, but economically speaking this would be sized to satisfy your demands, having an infinitely sized battery won't make the turbine produce more, it will only output what it, and the wind  can supply. Even if the turbines output was tied to the grid, an extremely large battery, the output maximum wouldn't increase, it is what it is. 

Thameraladnan

Huh ?  The end load for 24hours is what sets the required size of the battery.  Too large, and you waste money, too small and you deplete the battery and loose power.

great to have you mike95490 in this post.

I would again work it out starting from the nature of the load I want to supply and then I can choose the right wind turbine size. but I have to remember the wind regime in the site.

Your battery size has nothing to do with the about of power the turbine can deliver.

the reason I am thinking that way is the idea of having a 5kW diesel generator supplying a house having total power of 3kW of appliances.
the generator will supply whatever the load need as long as the load is within its rated power. but the diesel generator will not provide its max power when the load is less than 5kW. does it?


thanks for your comment again.