Tesla battery is good for suburban living but has limitations in a rural situation as the batteries can’t be used to operate a water pump that needs more than 30 amps to start and count be used as backup in a fire when the power goes off. Not sure if a 2nd Battery is added it would double amps
What kind of water pump are we talking about here? Tesla Powerwall specs say 7kw is available at peak. Big domestic pressure activated water pumps run at around 1 - 1.5 kw.
Tesla also claim to be your home’s power source when the grid goes down.
Powerwall is a battery that stores energy, detects outages and automatically becomes your home’s energy source when the grid goes down. Unlike generators, Powerwall keeps your lights on and phones charged without upkeep, fuel or noise. Pair with solar and recharge with sunlight to keep your appliances running for days.
Welcome to the community.
Assume you are referring to the current model of Tesla Powerwall - the peak short term output is approx 30A.
It is possible to operate Tesla’s Powerwall or some other brands of Solar battery product in parallel with another of the same brand. There may be restrictions on which models are most suitable. The configuration and components required are best left to a CEC accredited designer. Especially if you require an effective solution when power from the grid is lost to run the pump.
Tesla are supposedly bringing a higher rated Powerwall 3 model to Australia towards the end of 2024. (11.5kW peak output).
There are options other than Tesla. Solar battery brands such as Sungrow, Victron, SMA SunnyBoy, …. offering battery inverters which can be packaged with suitable battery packs. Several offer single phase inverters with greater starting capacity (EG Sungrow SH10.0RS 10kW continuous 63A max for 10 seconds). Most offer parallel operation options.
@syncretic has asked about your pump. It’s relevant because depending on your choice of
pump a single Powerwall or other brand may be sufficient.
Background:
If one is looking at a typical household pressure pump there are two common types in use. Newer constant pressure pumps use a variable speed controller (electronics). These do not draw high peak starting currents due to the energy conversion by the electronic controller. The older type of constant speed pumps which stop and start to regulate the pressure have very high starting currents. Typically referenced as the LOR (locked rotor current). It can be many times the full load running current stamped in the name plate of the motor. Typically (but sometimes not) the LOR is also found on the nameplate and data sheets. Something one needs to ask for either type and the model of pump you have installed.
We have a Grundfos CMBE constant pressure variable speed pump for our house supply. Grundfos, Davey and others offer competitive alternatives. It may be more cost effective to upgrade the house pump compared to a higher capacity inverter or multiple Powerwalls.
Sites such as the following (if you have not found it previously) can be a useful resource if one is looking at solar battery options. Tesla included.
P.S.
We have a second Honda powered fire pump. 400lpm. Up to 10 times the output of our house pump. Depending on your situation there are various options for home fire pumps including battery start. Relying on an electric house pump it is typically suggested one assess how secure the home electrical wiring, and solar battery installation is against incidental fire damage.
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If you are grid-connected, it is more likely the inverter will be the limitation. Grid-connected inverters don’t generally have any surge capacity, max output is close to rated output. Off-grid inverters on the other hand, have massive capacity for starting pumps relative to their rated capacity, often 2 or 3 times their continuous output rating.
If you have a 10kW inverter and a battery rated to deliver 7kW or more, you should be ok. Starting your pump unloaded can assist with reducing start-up current - closing the output greatly reduces load on impeller type pumps, which most FF pumps are. Don’t try it on a positive displacement pump though!
What is the output rating of your Tesla battery? It may be less for stand-alone than when grid connected.
