Battery function in daylight hrs ???

wannabeoffgrid

OK this the beginners corner so goes. In a offgrid system what is the function of the batteries at say 1pm after they are "charged"? Hypothetically after the batteries are charged doesn't the power come from panels to inverter then to house breaker panel for distribution of 110/220 vac. Or does power ALWAYS have to go through batteries before it's inverted for house uses? Could the system be used during peak sun without batteries to run drills/chargers/saws?

waynefromnscanada

Re: Battery function in daylight hrs ???

Hi wannabeoffgrid! Welcome to the forum.
Your question is a good one.
The answer:
Once the batteries are fully charged, a good charge controller will switch to Float mode and attempt to hold the batteries at a voltage lower than used for charging, to ensure the batteries stay fully charged, but without overcharging them. At this point, the charge controller will throttle back the power coming from the panels, and only allow through what is needed to maintain the batteries, + enough to power any loads that may be running. Yes, at this point, any power the inverter demands, will essentially pass on by the batteries and go directly to the inverter - - - UNLESS the load is larger than the panels can supply, in which case the batteries will automatically supply the difference as needed, but only when needed. When the heavy load is removed, the charge controller will automatically top the batteries back up, assuming the sun is still shining on the panels.
And NO, you cannot disconnect the batteries and run the inverter directly off the panels. The batteries are ESSENTIAL for stabilizing the whole electrical system, and without the batteries, nothing will work properly and it's possible both the inverter and charge controller could be damaged.

vtmaps

Re: Battery function in daylight hrs ???

wannabeoffgrid wrote: »

Could the system be used during peak sun without batteries to run drills/chargers/saws?

As Wayne pointed out you cannot use your inverter without a battery (or, at least, you won't be happy with the results).

But you can use solar electricity without batteries for some types of DC loads.

--vtMaps

wannabeoffgrid

Re: Battery function in daylight hrs ???

Just curious what would be some examples of dc loads that could be powered without batteries in the system?

vtmaps

Re: Battery function in daylight hrs ???

wannabeoffgrid wrote: »

Just curious what would be some examples of dc loads that could be powered without batteries in the system?

Motors (fans, pumps, etc) and heating elements come to mind. You may need a linear current booster to get motors to work efficiently.

--vtMaps

waynefromnscanada

Re: Battery function in daylight hrs ???

And those DC loads connected directly to the panels would have to be able to handle a wide range of changing voltages.