…… Solar-Electric Power Generation System Sizing tool?

[buttie]

Forget AC and any kind of electric heat. Get a gas kitchen range. Then maybe you could do a complete solar powered house.

Plus a gas hot water heater and dryer. We live quite comfortably on a 3.4kw off-grid solar system.

 

[LoupGarou]

On YouTube, they are saying you need a shunt with a Bluetooth readout in order to see the actual charge level of a LiFepo4 battery. The Bluetooth app for my charge controller does not show actual charge level, just charge rate. Something else to buy I guess.

Yes, just like Lead Acid and the Ni__ battery chemistries, battery voltage will only tell you a close ballpark figure of what you have left in the tank. And that is only true if the battery has not been charged or discharged at all in the last 30-60 minutes....

The only way to know for sure is a Coulomb counter based system. The good news is that with the advent of Hall Sensor based Columb counters that are getting more accurate, you don't have to use a shunt anymore on each separate battery (or the combination point if you are paralleling them together), but you can run a power lead from each battery through the same ferrite core and have it sample the H field for the whole lot at one time. This way one meter and Hall sensor can be used for the whole battery bank.

I still have one per battery, that way I can see if one battery in the paralleled bank is getting weaker than the others. This is what I did on all of my Lead Acid battery banks, and is what I am still doing on all of my LiFePO4s. Yes, it is an extra expense, but there are other options than the $500+ models out there now. I'm currently (no pun intended) using these:

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www.amazon.com

 

[WFK]

Yes, just like Lead Acid and the Ni__ battery chemistries, battery voltage will only tell you a close ballpark figure of what you have left in the tank. And that is only true if the battery has not been charged or discharged at all in the last 30-60 minutes....

The only way to know for sure is a Coulomb counter based system. The good news is that with the advent of Hall Sensor based Columb counters that are getting more accurate, you don't have to use a shunt anymore on each separate battery (or the combination point if you are paralleling them together), but you can run a power lead from each battery through the same ferrite core and have it sample the H field for the whole lot at one time. This way one meter and Hall sensor can be used for the whole battery bank.

I still have one per battery, that way I can see if one battery in the paralleled bank is getting weaker than the others. This is what I did on all of my Lead Acid battery banks, and is what I am still doing on all of my LiFePO4s. Yes, it is an extra expense, but there are other options than the $500+ models out there now. I'm currently (no pun intended) using these:

Loading…

www.amazon.com

I support the use of Hall Effect sensors for current (A) or charge (Coulombs) because the shunt voltage (drop) losses have always bothered me in high current applications.
Because of voltage drop consideration of cables (and CONNECTIONS) I had my system on a 24-V DC bus from the beginning (with a 4kVA sinusoidal Inverter.)

 

[SackLunch]

Plus a gas hot water heater and dryer. We live quite comfortably on a 3.4kw off-grid solar system.

It is amazing what you can live comfortably without.

With the solar, I can run the electric hot plate, coffee pot, crock pot, or instapot on sunny days. On snow days I can use the wood stove. There's a propane stove for backup or for the convenience of tea on a cool, late summer evening.