What size solar generator do I need?

People ask what size generator they need, and the answer is always two numbers, not one. The first is how much energy you use in a day. The second is how much power you draw at the same instant. A battery is sized by the first. An inverter is sized by the second. Buy a big battery behind a small inverter and the lights still go out when the well pump starts.

Only the first number belongs on this page. Daily energy is what the storage is for. Power and surge decide whether a particular unit will run your appliances at all, and the load calculator works both of them out from the same appliance list.

There is one place where the two numbers collide. A unit with a large battery but a small inverter is common in the cheaper classes, and it looks generous on the box. It will hold a lot of energy and still refuse to start a fridge compressor. Read the output rating before the capacity rating, every time.

If your daily energy is still unknown, the honest first step is a load count, not a shopping trip. Fifteen minutes with a spreadsheet and the labels on your appliances beats any rule of thumb, including the ones on this page.

The number printed on the box is nameplate capacity. The number you can spend is usable capacity, and the two differ by the depth of discharge the manufacturer allows. A 2,048 Wh pack at 85 % gives you 1,741 Wh of actual draw. The other 307 Wh stays in the pack as a guard against over-discharge.

So the sizing rule runs backwards from what people expect. You do not start with the battery and ask what it covers. You start with the energy you need, then divide by the depth of discharge to find the nameplate you have to buy.

That division is where most estimates go wrong by twenty percent. Adding two days of autonomy and then forgetting the depth of discharge produces a number that looks right on paper and dies on the second night.

Eighty-five percent is a planning value, not a law. Some lithium iron phosphate packs publish a lower usable limit for a longer cycle life, and some publish higher. Use the figure on the specification sheet for the model you are considering, and treat 85 % as the neutral default when you have no sheet in front of you.

If your answer lands in the 1-2 kWh class, that is the tier most portable stations cover: Anker SOLIX C1000 Gen 2 (check current price).

Below is the same division done across the range of daily energy most US homes land in, for the three outage lengths people actually plan for. Every cell is daily energy multiplied by days, divided by 0.85. Nothing else is folded in.

The jump from one day to two is the expensive one. It doubles the nameplate you need for a house that already had a plan. The jump from two days to three is a smaller relative step, which is why people who have been through one long outage usually go straight to three.

There is a practical ceiling in this table. Portable stations sold in the US top out around 4 kWh of nameplate in a single box. Anything above that row is either an expansion battery on the same product line or a second unit in parallel where the manufacturer supports it. That is not a marketing limit, it is what the largest 120 V single-box units we track offer.

Take the default set on this page: a refrigerator, four LED bulbs, a router, a phone charger and a television, 2,170 Wh a day. Run the same kit through four plans and watch the nameplate move while the daily energy stays put. This is the only number in the table that changes the answer.

The last row is the one worth staring at. Raising the depth of discharge from 85 % to 95 % removes 538 Wh of nameplate from a two day plan. That is real money, and it is only available if the pack you buy actually tolerates that depth on a regular basis. Do not assume it does.

Notice also what did not change. Every row keeps the same daily energy. Autonomy and chemistry move the nameplate; they do not move your house. This is why the sizing question can be answered before you pick a brand.

A battery is a countdown timer. An array turns it into a supply. The array figure is daily energy divided by peak sun hours and then divided again by system efficiency, which covers the charge controller, the wiring, and the fact that a panel almost never sits at its rated output.

At four and a half peak sun hours and 75 % efficiency, 2,170 Wh a day needs 643 W of panels. At four sun hours it needs 723 W. At five it needs 579 W. The spread between a good site and a poor one is not small.

Panel wattage is not the same as panel count, and the count is what you buy. At 400 W per panel, 643 W rounds up to two panels. That rounding matters more than the exact wattage, because you cannot buy one point six panels.

Four peak sun hours is a planning average for much of the lower 48 states. Coastal areas and northern winters run lower, the desert southwest runs higher. The National Renewable Energy Laboratory publishes the monthly numbers by location, and the spread between December and June is large enough to change a panel count on its own.

The order of purchase follows from the diagram. Buy the battery for the night first, then the array for the days. Doing it the other way leaves you with generation you cannot store, which is a common way to spend money and still sit in the dark.

One check before any array purchase. Confirm the solar input limit on the station you are buying. A 600 W panel set feeding a unit capped at 300 W of input will simply clip, and you will own panels you cannot use. The limit is on the specification sheet, and it is the number people forget to read.

If you plan to grow the system, buy a unit whose solar input can grow with it. A station that caps input at 200 W forecloses every expansion you might want later, and that cap is rarely mentioned in the headline specs.

Capacity classes are not marketing categories. Each one covers a different outage for the same 2,170 Wh a day house, and the class names hide how much of the published number is usable. The table converts nameplate into hours of that day so the classes can be compared on one scale.

The 300 Wh row is the one that disappoints people most often. It is a phone and router device that can also run a laptop. It is not an outage kit, and no amount of careful reading changes that.

The jump from 1,024 Wh to 2,048 Wh doubles the battery and roughly doubles the price. The jump from 2,048 Wh to 3,072 Wh buys half a day more autonomy. That is the point where people start asking whether panels are the better use of the same money.

Above 4,096 Wh there is no single box in the 120 V category among the models we track. The next step is an expansion battery on the same product line, and those are only sold for some models. Check that the line exists before you buy into it.

Ordered by nameplate, not by price or brand. Each entry says who it fits and who should walk past it. Every link goes to a product page, and this site does not print prices.

EcoFlow RIVER 3 Plus is 286 Wh with a 600 W output. EcoFlow RIVER 3 Plus fits a bag, a router and a laptop for an evening. Skip it if you need a fridge, because it will not start one.

Anker SOLIX C300 is 288 Wh with a 300 W output and a 600 W rated surge allowance. Anker SOLIX C300 fits a small flat and a phone-first outage. Skip it if your plan includes anything with a compressor.

Jackery Explorer 300 is 292 Wh with a 300 W output. Jackery Explorer 300 fits a first-time buyer who wants something light. Skip it if you already know your daily energy is over 400 Wh.

BLUETTI AC70 is 768 Wh with a 1,000 W output. BLUETTI AC70 fits a fridge through one night and nothing more. Skip it if you want two nights, because 653 Wh of usable energy will not stretch that far.

Jackery Explorer 1000 v2 is 1,070 Wh with a 1,500 W output. Jackery Explorer 1000 v2 fits the 1,024 Wh row of the table with a little headroom. Skip it if your total load needs more than 1,500 W at once.

Anker SOLIX C1000 Gen 2 is 1,024 Wh with a 2,000 W output and a 3,000 W peak. Anker SOLIX C1000 Gen 2 fits a house that needs power headroom more than capacity. Skip it if the battery figure is the binding constraint, because the class is the same.

EcoFlow DELTA 3 is 1,024 Wh with a 1,800 W output. EcoFlow DELTA 3 fits a mixed load of fridge and electronics. Skip it if you need the full 2,048 Wh class, because this is not it.

Jackery Explorer 2000 v2 is 2,042 Wh with a 2,200 W output. Jackery Explorer 2000 v2 fits the 19.3 hour row and covers a full day of the outage kit. Skip it if you have committed to three days.

BLUETTI AC200L is 2,048 Wh with a 2,400 W output and a 3,600 W surge rating. BLUETTI AC200L fits a load with a pump or a fridge compressor. Skip it if you need the biggest single box, because 4,096 Wh is the ceiling of this category.

EcoFlow DELTA 3 Max Plus is 2,048 Wh with a 3,000 W output. EcoFlow DELTA 3 Max Plus fits a house that draws hard for short periods. Skip it if your problem is run time rather than power.

Anker SOLIX F2600 is 2,560 Wh with a 2,400 W output. Anker SOLIX F2600 fits the step just above the two-day class. Skip it if the arithmetic says you need 7,659 Wh, because this is less than half of that.

EcoFlow DELTA 3 Ultra is 3,072 Wh with a 3,600 W output. EcoFlow DELTA 3 Ultra fits the 28.9 hour row with margin. Skip it if you need three full days without charging.

EcoFlow DELTA Pro 3 is 4,096 Wh with a 4,000 W output. EcoFlow DELTA Pro 3 fits the top of the single-box category, 38.5 hours of the outage kit. Skip it if 4,096 Wh is not enough, because the next step is a different kind of purchase.

If you want the panels bundled rather than sourced separately, Jackery Solar Generator 1000 v2 with a 200 W panel is one box with both halves. It fits the one-night plan and the panel count this page computes for it. Skip it if your daily energy is above 1,070 Wh.

One: sizing on nameplate instead of usable energy. A 2,048 Wh pack gives 1,741 Wh of draw at 85 %. Plan a two-day backup on 2,048 Wh a day and you are short before the second night begins.

Two: buying capacity to cover a power problem. The inverter rating is a separate number, and the cheaper units in every class have the smaller one. A 1,024 Wh box with a 600 W output will not start a well pump no matter how carefully you sized the battery behind it.

Three: forgetting the second purchase. Storage without generation is a countdown timer. Generation without storage is a daytime-only supply. The calculator prints both figures on purpose, and the two are not substitutes.

Each mistake is cheap to make and expensive to discover. A wrong power figure shows up as a device that will not start, which at least announces itself. A wrong energy figure shows up as a dead battery on day two, which does not.

There is a fourth that belongs to a different page. Counting appliances that run on 240 V inflates the daily figure without any of them being connectable to a 120 V station. Dryers, ranges and central air belong on the electrician side of the line.

A capacity claim is three claims stacked together: the nameplate, the depth of discharge, and the output rating. Product pages publish the first, sometimes publish the second, and frequently blur the third with a marketing peak figure that is not a motor surge rating.

The peak figure is where manufacturer claims and third-party measurements most often differ. A unit advertised at 2,000 W of peak output may be listing a short-duration boost for resistive loads, not the surge a compressor needs. Those are different numbers, and only one of them starts a fridge.

On this site we hold one rule for that: where a manufacturer's headline figure and the specification sheet disagree, the sheet wins, and where a third party has measured the unit we say so instead of quoting the box.

Three things are worth confirming on the specification sheet before you spend anything. The usable capacity, the continuous output, and the shutdown behavior when a load exceeds that output. The third one decides whether a mistake is an annoyance or a dead unit.

This is not professional electrical advice. Anything that involves house wiring, a transfer switch or a new breaker needs a licensed electrician, and consult your local code official before installing anything permanent. A portable station plugged into a wall outlet is an appliance. A circuit fed from a battery is a different kind of work.

The formulas on this page are arithmetic, not opinion. The planning values behind them are the ones worth checking, and each one is listed below with the source and the date it was read.

Appliance draw figures come from our own load data, which lists 150 appliances with a source and a read date for each. Where the label on your appliance disagrees with any table here, the label is right.