SOLAR EQUIPMENT / INVERTER PLANNING
Work out what needs to run together, what needs help getting started, and what your battery can actually supply.
The coffee maker is on. The refrigerator starts. The inverter quits. That is a frustrating way to discover that a daily energy total and an inverter power rating answer different questions.
An inverter supplies AC power from a DC source. An inverter/charger also adds charging functions, with features that vary by model. Start with your loads and your system architecture before comparing the largest numbers on the box.
Make a list of appliances that need AC power. Record their operating power, required voltage and frequency, and whether they can start while other loads are already running. Keep DC loads in the overall battery budget, but do not add them to the inverter’s AC output total unless they actually use that output.
Suppose the following AC loads overlap. Every number is invented for this example; use measurements and manufacturer information for real equipment.
| AC load | Assumed running power |
|---|---|
| Coffee maker | 900 W |
| Refrigerator while running | 100 W |
| Laptop charger | 60 W |
| Lights | 20 W |
| Total | 1,080 W |
The inverter must support that running demand under its actual operating conditions. If the coffee maker is kept off, this example drops to 180 W. Scheduling can reduce simultaneous power, but it does not erase the coffee maker’s energy consumption when you eventually use it.
A 1,080 W total is not enough evidence to select a particular inverter. You still need startup behavior, continuous output at the installation temperature and the manufacturer’s sizing requirements. Adding an arbitrary percentage cannot resolve missing load information.
Motors and compressors may briefly demand more than their normal operating power. Find the startup specification for the exact appliance or have it measured with suitable equipment. A general-purpose energy meter may not capture a short inrush accurately.
For another hypothetical check, suppose the refrigerator requires 700 W during startup while the other three loads draw 980 W. The combined demand during that event is 1,680 W. An inverter’s peak rating must support the required duration and load type. A peak number without a duration leaves the important part unanswered.
Some inverter ratings emphasize VA, while appliance energy budgets often use watts. Power factor and the manufacturer’s rating conventions matter, so a 2,000 VA label does not automatically establish 2,000 W of usable continuous output for every load. Read both ratings and the application guidance.
As an illustration, supplying 1,000 W AC at an assumed 90% inverter efficiency requires roughly 1,111 W DC before other losses. At an assumed 12 V battery voltage that is about 93 A; at 24 V it is about 46 A. Actual voltage varies, and these are conceptual comparisons, not cable or fuse specifications.
Check the bank’s continuous and peak discharge limits, battery-management system, supported voltage range and the inverter manufacturer’s recommended pairings. Capacity in amp-hours alone does not establish adequate current delivery.
Confirm the output waveform required by your appliances, AC voltage, frequency, outlet limits and any split-phase requirements. A 120 V outlet cannot serve a 240 V appliance just because the inverter has enough watts. Hardwired building circuits need an appropriate professionally designed installation.
These local notes are not submitted or saved. Print to keep your checklist.
Our inverters and batteries guide explains the relationship. If you want an integrated unit instead of separate components, compare portable power stations, checking both output and storage. Return to the off-grid planning guide to connect the decisions.
No. Runtime depends on usable stored energy and actual consumption, including losses and idle draw. More output capability is not more battery capacity.
Do not assume so. Such modes have equipment restrictions and may alter output behavior. Use the model’s continuous rating and documented compatibility for your intended appliances.
Examples are original AZSP calculations with stated assumptions. Victron’s inverter/charger selection guidance covers model ratings, system voltage and manufacturer-recommended battery pairings. Consult the exact appliance and inverter manuals before selection.
AZSP educational guide. Numerical examples are hypothetical planning exercises, not measured product performance or a finished system design. Product guides may contain affiliate links that earn AZSP a commission.