Help choosing a battery

Screwdriva

Reed_Richards said:

Just to be absolutely clear, "they would use the inbuilt inverter" as the only inverter so serving both the battery and the solar panels?  And what happens if that inverter fails before the battery, as the OP asked?

Yes.

Tesla has a firm "no repair only unit replacement" policy for the duration of the warranty. I specifically asked what that meant and the answer I received was, "we will replace the installed faulty PW3 at our cost within a reasonable timeframe". 

I then asked what happens to the cells in any faulty battery. I was told they are re-used to assemble large scale storage solutions, which I thought was very environmentally responsible.

Solarchaser

Since there are no quotes in the op, I cannot comment on how cheap the op has managed to get a pw3 installed for, Internet searches suggest between 7k and 9k, against a £1500 battery at the same capacity plus say £1000 for inverter, I maintain that Tesla is nowhere near the best for roi

thevilla

I must be missing something but I don't see a huge improvement in PW3 vs. PW2 other than maximum power output.  I certainly didn't see the PW3 release and wish I'd waited before going for the AIO.  Rumour has it it is lfp?  Maybe cheaper with software gateway in the future?

Edit: one thought for the op. if applicable, consider separating any EV charger from the house circuit to prevent the battery discharching into the ev.  Mine is separate, my sister's is not and her PW2 empties into the ev on some IO sessions.

Qyburn

Solarchaser said:

Qyburn said:

That's true of a DC coupled battery like our Solaredge.

Not really the case with an AC coupled battery like Tesla. In that case it's the battery that decides when to charge or discharge. I assume the inverter just whacks out it's full power and doesn't know or care whether it's being consumed by house loads or by the battery.

Batteries are DC not AC, and so the inverter sets the limits.

OK but if you read my post you'll notice I wrote "DC coupled" and "AC coupled". In the former the battery sits on the DC side of the solar inverter so charging does not require AC to DC conversion.

An AC coupled battery has its own inverter so that battery charging from solar goes DC to AC to DC. Controlling whether the battery charges or discharges and thus whether electricity I'd exported, imported or in balance, is done by the battery's inverter and not by the solar inverter.

Solarchaser

The battery will be charged by a charge controller to convert the few hundred volts DC into usually a nominal 50v depending on batteries, that charge controller sits within the inverter, and that dictates how fast you can charge and discharge based on how much current it can handle

Heedtheadvice

Yes comments that a battery ( of cells) is always DC ( I do not like the term AC battery!) is correct, it is the charge power source that is AC or DC.

At some point for either charge power source there is always control of the charge current be it as part of the inverter 'charger' circuit from AC or DC or other means such as within a hybrid inverter or charge controller.

When from a AC source ( 'AC Inverter') doing the charging or a DC source ( via a voltage converter/charge controller ) there will always be losses. Not sure if there is a significant difference in their relative efficiency.

The naming in common use that can confuse is that  in a supposedly 'AC Battery' the conversion from AC to DC and control of charge current forms part of the battery system/package rather than a separate unit.