1. Describe Your Backup Load
Load shedding is why most people buy a power station, so start with the outage you actually expect. List the devices you need to keep running and the backup hours you need each one to run — your own estimate of how long an outage lasts for you. The card totals those into Total Load (watts) and Total Energy (watt-hours) for that worst case. These devices are shared, so every power station below is judged against the same outage.
Device Wh = Watts × Qty × Backup Hours · Total Load (W) = sum of Watts × Qty
Running More Than One of the Same Device
The Qty column saves you entering three fans as three rows. Quantity multiplies the row both ways: the load it adds is Watts × Qty, and the energy it adds is Watts × Qty × Backup Hours. A blank quantity counts as one. Qty takes whole numbers, while Watts and Hours accept decimals — the arrow keys step a field by 0.5.
Don't Know a Device's Wattage?
You do not need to know the watts to use this. The list of common appliances appears as soon as the cursor lands in an empty Device field — LED bulb, Ceiling fan, WiFi router, Phone charger, Refrigerator and more — and it filters down as you type. Move through it with the arrow keys and press Enter to take one, or click it; press Escape or leave the field to dismiss it. Picking a device fills the Watts cell, and sets Qty to 1 if you had left it blank. The wattage is filled in for you and shown with a dashed border, so you can see it is a typical figure rather than your own. Every suggested value also states the realistic range for that appliance. Type any number over it and the dashes disappear — a figure you enter is never overwritten by a suggestion.
These are typical draws, not ratings off the label, and for two appliances those differ enough to matter. A phone draws its own charging rate, so a 45 W charger still only pulls about 15 W. A fridge's compressor runs roughly a third of the time, so it is better entered with fewer hours than a lower wattage. If you have the appliance to hand, its label or power adapter states the real figure — usually in watts, or as volts × amps.
Same Outage Time for Everything?
You can also skip hours altogether. Runtime is worked out from the total load, not from the hours — so the moment your devices have wattages, every station shows how long it will run them. Hours are what turn that load into total energy (Wh), and they are what the Coverage figure needs. Leave them blank and you still get runtime; the card tells you when hours are missing and what they would add.
During a power cut your devices usually all run for the same stretch. Tick “Same backup time for every device” and enter that one number in the Backup time (h) field beside it — it fills the Hours column for every row and locks those fields, so you only type it once. Untick the box and the Hours column becomes editable again with the values left in place. Leave it unticked if devices run for different lengths: a router on all night, a fridge cycling on and off.
Adding, Removing and Typing Rows
Add Device adds a row at the bottom and puts the cursor in it. The bin icon at the end of a row removes that row; if it was the last one, an empty row is left in its place so the table always has somewhere to type. Figures go straight into the row — anything that is not a valid number is given a heavier outline and left out of the totals, rather than being read as zero and quietly shrinking your load.
2. Check the Shared Settings
These live behind “Shared Settings” in the navbar. Pick the currency used for station prices, and adjust the derate factors if you want more optimistic or more conservative recharge estimates. Typical values: solar 1.15–1.25, AC ~1.1. Each change applies as you make it, so the results behind the dialog are already up to date when you close it.
3. Add Power Stations
Click “+ Add Power Station” beside the station tabs. Choose “From Catalog” to pick a brand, then search or scroll its listed models — the published specs are filled in for you and stay editable. Where a listing does not state a figure, that field is left for you to enter and the form says which ones. Choose “Custom” to enter every spec yourself. Required fields are marked with an asterisk (*). Catalog prices come from a BDT source listing, so a price is filled in only while the currency under Shared Settings is Tk; in any other currency that field is left blank rather than re-labelling the number. A model already on the page is tagged “Added”. The station is added when you press “Add Station”; “Cancel” closes the form and clears it. To change a station later, press “Edit Specs” in its summary — the same form opens filled in, and “Save Changes” updates it in place, keeping its position in the comparison. Each station's tab carries a 0/3 counter showing how many of its three results it can produce, and the small × on the tab deletes the station after a confirmation.
4. Read the Results
Each station tab shows its specs and three results, recomputed automatically whenever anything changes:
Runtime (h) ≈ (Capacity Wh × 0.85) ÷ Total Load W
Solar Recharge (h) ≈ (Capacity Wh ÷ Solar Input W) × Solar Derate Factor
AC Recharge (h) ≈ (Capacity Wh ÷ AC Input W) × AC Derate Factor
0.85 is the inverter efficiency factor for AC output; DC loads may run longer. The derate factors cover real-world losses such as sun angle, panel temperature and charging losses. A warning appears if your total load exceeds a station's continuous AC output. The station summary also shows two derived figures: Coverage — how many days one charge covers your backup energy need — and Price / Wh, the value per watt-hour.
5. Compare and Save the Report
Once every included station has its inputs, the comparison appears; until then the section lists exactly what is still missing, and the “Go” button beside each line jumps to the field that needs it. Click any column heading to rank by it, and click again to reverse the order; the blue bars show how much more or less a station offers at a glance. The longest runtime and the shortest solar and AC recharge times carry a green “Best” badge. Switch between “Ranked” and “All Specs” at any screen size — Ranked lists the stations best-first for whichever metric you pick (Runtime, Coverage, Capacity, Solar Recharge Time, AC Recharge Time or Price), and All Specs is the full table. On a phone the table becomes one card per station and Ranked leads by default, because a stack of cards cannot be compared. Untick “Include in comparison” on a station to keep it on the page without it taking part in the table. “Download PDF” opens the print dialog — choose “Save as PDF” to get a report with your backup load, each station's summary and the comparison table.
6. What Each Comparison Column Means
Hover, tap or keyboard-focus the ⓘ beside any column heading — or beside any button under “Rank by” — to see the same short explanation in place. Every station is measured against the same backup load, so the columns can be read straight across.
- Price
- What the station costs, in the currency you chose under Shared Settings. If your stations are priced in different currencies the comparison says so instead of ranking them against each other, because those numbers are not comparable.
- Price / Wh
- Price divided by capacity — what you pay per watt-hour of storage. Lower is better, and it is usually the fairest way to compare stations of different sizes.
- Capacity
- The energy the battery can store, in watt-hours (Wh). Only about 85% of it reaches your devices through the AC inverter, which is why the runtime, coverage and recharge figures all start from capacity × 0.85.
- Coverage
- One charge's usable energy (capacity × 0.85) divided by your total backup energy need. A value of 1.0 means the station covers your outage exactly; below 1.0 it falls short and you would need to recharge or trim your device list. Higher is better.
- Runtime
- How long one charge runs your whole load: (capacity × 0.85) ÷ total load in watts. It ignores the backup hours you entered, because it is a rate — how long the station lasts at that draw. Longer is better.
- Solar Recharge
- How long to refill from solar panels: (capacity ÷ solar input W) × the solar derate factor. Shorter is better. It assumes steady, full-strength sunlight, so treat it as a best case rather than a promise.
- AC Recharge
- How long to refill from a wall socket while the grid is up: (capacity ÷ AC input W) × the AC derate factor. Shorter is better, and it is the number that decides how quickly you can turn the station around between outages.
Columns that can be ranked show a small ↕ arrow; click the heading to sort by it and click again to reverse the order. The green “Best” pill marks the longest runtime and the shortest recharge times, and the blue bars show how each station compares with the best one in that column.
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