P91-1kLi vs APC Smart-UPS SMTL1000RM2UCNC
The P91-1kLi and APC Smart-UPS SMTL1000RM2UCNC are both short-depth 1000 VA lithium rack UPS systems with different architectures. The P91-1kLi is online double-conversion at 10.6 inches of rack depth; the SMTL1000 is line-interactive at 12.5 inches. The P91-1kLi adds LiFePO₄ chemistry, 900 W instead of 800 W, operation up to 50 °C, optional wall mounting with PV-WMB, TAA compliance and a 6-year warranty. It ships November 2026.
What the P91 Li brings
- Online double-conversion vs line-interactive topology
- 10.6 in rack depth vs 12.5 in
- 900 W vs 800 W at the same 1000 VA
- Eight outlets, with a controllable bank of four, vs six
- LiFePO₄ chemistry for lifecycle and thermal stability
- Operation up to 50 °C for edge and non-conditioned sites
- TAA compliance and a 6-year warranty
Side-by-side specifications
| Specification | Xtreme Power P91-1kLi | APC Smart-UPS SMTL1000RM2UCNC | Advantage |
|---|---|---|---|
| Topology | Online double-conversion | Line-interactive (6 ms transfer) | P91 Li – zero transfer time |
| Depth | 10.6 in rack-mounting depth (11.6 in with bezel) | 12.5 in | P91-1kLi – shallower |
| Capacity | 1000 VA / 900 W | 1000 VA / 800 W | P91-1kLi – 100 W more real power |
| Battery chemistry | LiFePO₄ | Lithium-ion | P91 Li – LiFePO₄ |
| Battery design life | Up to 15 years | Up to 10 years | P91 Li – longer lifecycle |
| Runtime (P91-1kLi published) | 7 min at 900 W · 20 min at 360 W · 44 min at 180 W | See APC runtime data for your load | Compare at your load |
| Recharge | About 3 hours | About 3 hours | Matched |
| Outlets | 8 × NEMA 5-15R (one controllable bank of 4) | 6 × NEMA 5-15R | P91-1kLi – more outlets |
| Individual outlet control | No (bank control only) | No | Not in this class; see the J90 |
| Temperature rating | Up to 50°C | 40°C typical | P91 Li – higher-temp operation |
| Deployment | Rack / tower / wall (with PV-WMB) | Rack / tower | P91-1kLi – wall-mount option available |
| Network management | Optional Web/SNMP card | Network card and SmartConnect included | APC – included |
| TAA compliance | Yes (standard) | No (US-suffix SKUs only) | P91 Li – TAA standard |
| Warranty | 6 years, UPS and battery (USA and Canada) | 5 years | P91 Li – longer warranty |
| Availability | Ships November 2026 | Available now | APC – shipping today |
APC figures from published APC product listings, checked October 2026; confirm against current vendor documentation. Depths as published; the P91-1kLi figure is rack-mounting depth behind the front rail. The SMTL1000RM2UCNC is line-interactive; the P91 Li is online double-conversion. TAA compliance note: P91 Li models are TAA-compliant as standard. APC Smart-UPS SMTL models require the “US” suffix designation (e.g., SMTL1000RM2UCUS) to meet Trade Agreements Act requirements for federal procurement; the SMTL1000RM2UCNC model shown here does not include US TAA compliance.
Choosing between them
At 1000 VA, both systems target the same capacity. The core difference is topology: the P91 Li runs the load through its inverter continuously (double conversion, zero transfer time), while the line-interactive SMTL corrects voltage with AVR and transfers to battery on an outage. The P91-1kLi is also shallower at 10.6 inches of rack depth against 12.5. The P91 Li adds higher-temperature operation (up to 50°C), optional wall-mount (with PV-WMB), TAA compliance, and a longer warranty. The APC offers integrated network management out of the box.
Choose the P91 Li if you need
- True online double-conversion protection
- Less rack depth: 10.6 in vs 12.5 in
- LiFePO₄ and operation up to 50°C
- Edge or non-conditioned environments
- TAA compliance and extended warranty
The Smart-UPS SMTL may fit if you need
- A line-interactive UPS for cost-sensitive deployments
- Voltage regulation without full double-conversion
- Integrated network management built-in
- Alignment with the APC Smart-UPS ecosystem
- A unit that ships today
P91-1kLi vs SMTL1000: common questions
Which is shallower, the P91-1kLi or the APC SMTL1000RM2UCNC?
The P91-1kLi needs 10.6 inches of rack-mounting depth, about 11.6 inches with its front bezel. APC lists the SMTL1000RM2UCNC at 12.5 inches deep.
What is the difference between online and line-interactive at 1000 VA?
An online UPS such as the P91-1kLi runs the load through its inverter all the time, so there is no transfer when power fails and the output is regulated continuously. A line-interactive UPS such as the SMTL1000 passes utility power through with voltage correction and switches to battery on an outage, with a short transfer (about 6 ms for this model).
Is the APC SMTL1000RM2UCNC TAA compliant?
No. APC states that its TAA-compliant SKUs carry a US or TAA suffix; this SKU carries neither. The P91-1kLi is TAA compliant as standard.
When is the P91-1kLi available?
It ships November 2026. Call (800) 582-4524 to quote a project or reserve units.
What warranty and protection come with the P91-1kLi?
Six years on electronics and battery in the USA and Canada, reduced to 2 years for continuous operation between 40 and 50 °C, and 2 years depot repair elsewhere, plus a $50,000 load protection policy on connected equipment in the USA and Canada.
Related comparisons
Comparing 1000 VA lithium UPS options?
The P91-1kLi brings online double-conversion at 10.6 inches of rack depth, LiFePO₄, up to 50°C operation and TAA compliance to the 1000 VA segment. Ships November 2026; quote it now.