diy solar

diy solar

Grid charging and using at same time

zlamb

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Joined
Apr 30, 2021
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I have decided to build my system myself instead of going with an AIO. How do I get the capabilities of an AIO charging batteries with grid or generator and also using the power from grid or generator to power my system?
 
Several options.
Either use an inverter charger, or get a power supply and feed it into the charge controller on the PV input.
 
Grid cannot be put on the charge controller unless you have grid connected to a dc power supply.
After looking at Wills videos do I need an Automatic Transfer System like the one shown on the video "DIY 2000 watt, 24v Solar Power System w/ LiFePO4 Batteries"
 
After looking at Wills videos do I need an Automatic Transfer System like the one shown on the video "DIY 2000 watt, 24v Solar Power System w/ LiFePO4 Batteries"

Some inverters have an internal transfer switch. They function like a UPS - if grid (shore power) is available, it supplies the load. When not available, battery supplies load. If inverter doesn't contain it, then can be external (or use a battery charger as Supervstech says.)
More difficult is using up to 100% of PV to supply load plus additional power as needed from grid.
Without grid, up to 100% from PV and balance from battery is normal operation.

Once you size your planned system (Wh of battery, W of PV, W of continuous AC, W of surge AC), you can compare various AOI or individual components.
 
Some inverters have an internal transfer switch. They function like a UPS - if grid (shore power) is available, it supplies the load. When not available, battery supplies load. If inverter doesn't contain it, then can be external (or use a battery charger as Supervstech says.)
More difficult is using up to 100% of PV to supply load plus additional power as needed from grid.
Without grid, up to 100% from PV and balance from battery is normal operation.

Once you size your planned system (Wh of battery, W of PV, W of continuous AC, W of surge AC), you can compare various AOI or individual components.
Which inverters have the internal transfer switch?
 
Many of the inverters intended for RVs have an internal transfer switch and comply with UL-<something or other> in terms of bonding neutral to ground only when shore power isn't present.
Outback has had a number of inverters which do that. Some were for vehicles & RVs, some for on-grid or off-grid homes.
Victron. Many others.
I use a large SMA inverter which accepts grid power, but doesn't do neutral bonding. That is also common.

Pretty much any inverter with AC input and AC output will do that. But only some can do such things as using battery power to supplement AC input (for instance, 15A 120V extension cord plus PV/battery to run larger loads.)

Start by deciding how many watts of AC you need, then look at inverters in that range. Inverters under 1kW probably don't. From 2kW to 15kW there are many which work with the grid, and many which are battery only. Just search for "inverter charger"
 
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