| Battery comparison | Tesla Powerwall 2 | CPS ESS 4kw/10kwh | CPS ESS 8kw/20kwh |
| Capacity kwh | 13.2 | 10.24 | 20.48 |
| Whole home backup | no | yes | yes |
| EV charger included | no | yes | yes |
| Battery size extendable | no | yes | yes |
| Secondary power input | no | yes | yes |
| Switch time to backup | 5 sec + | <50millisec | <50millisec |
| Max continuous power kw | 5 | 4 | 8 |
| Burst power kw | 7 | 10 | 20 |
| Grid tied max continuous power kw | 5 | 12 | 12 |
| Charge EV in backup mode | no | yes | yes |
| Battery voltage | 50V | 54V | 54V |
| Grid-tied | yes | yes | yes |
| Charge battery from solar | yes | yes | yes |
| Charge battery from grid | no | yes | yes |
| Battery feed grid | yes | yes | yes |
| Solar inverter included | no | yes | yes |
| Weight kg | 122 | 152 | 220 |
| stackable | yes | yes | yes |
We’re often asked why CPS ESS is preferable over a Powerwall 2. The main reason customers choose the CPS ESS system is that it provides a simple whole home backup system – since the system can handle up to 12kw (50A) in grid-tied mode and 50kw (200A) with an ATS, we can provide ANY home with a complete power system that can run ALL normal home loads in grid-tied mode, and even perform EV charging during power outages. The switch from grid-tied to battery/solar power is so fast customers can’t tell when it happens – whereas the Powerwall has a several second delay before the battery kicks in – causing many appliances to loose their memory and can cause computer systems to loose data. The Powerwall 2 is limited to the 5kw continuous operation – a fraction of what the CPS ESS can handle in grid-tied mode. The CPS ESS also uses one inverter for the entire system – this simplifies the construction and provides higher overall efficiency – the solar->battery storage efficiency is over 96%.
For those considering going off-grid, the secondary power input provides a means to connect another power source to your system, such as a wind generator or an inverter powered by your EV. Modern EV’s can now provide typically up to 1.5kw continuously from the traction battery by routing through the 12V auxiliary system. This makes the entire traction battery available for emergency storage through the secondary power input. The CPS ESS system is vehicle to grid ready.
The CPS ESS can also have larger battery sizes for those considering off-grid applications or those adding storage to existing solar. Battery size can be increased in 10kwh increments, without incurring the additional costs of an inverter and associated electronics. Normally battery size 2.5X the solar size is ideal for storing enough energy from solar to operate off-grid one day to the next, when solar refills the battery. Example – for an existing 8kw solar system, you can add a 4kw/20kwh CPS ESS AC coupled system.
Charging battery from grid must be kept below 25% of total use to qualify for SGIP rebates.