We Compared 4 Solar Generators for Greenhouse Fans and Pumps

Most greenhouse buyers start by asking how big a battery they need. For a structure that draws the same modest load every day and sits under a panel, the better first question is how quickly the pack can take that energy back.

The ratio that matters in a greenhouse#

Set the solar input against the capacity it has to fill and the four units here separate sharply. The C1000 accepts 600W into 1056Wh, which is 0.57W of array per watt-hour of storage. The DELTA 2 Max manages 0.49 and the S2000 only 0.20.

In practice, derate a rated array to about 80% of its figure and the C1000 charges at roughly 480W. Our reference greenhouse day, defined in the buying guide below, draws about 1.17kWh from the pack. That is replaced in around two and a half hours of strong sun. The whole 1056Wh pack refills in about 2.2 hours.

That is the number a grower actually cares about. A short clear window between weather fronts is enough.

What it runs, and for how long#

The 1800W inverter is not the limiting factor for the steady part of a greenhouse load. A 60W inline exhaust fan, a 20W horizontal airflow fan and a 300W irrigation pump running together come to 380W, well inside the rating.

The start-up instant is a different question. SurgePad’s 2400W is a voltage-lowering boost mode, so it does nothing for a motor, and the figure a pump start has to fit inside is the 1800W continuous rating, leaving about 1420W of margin above the running load. A small diaphragm or centrifugal pump fits inside that. A jet or shallow well pump with a stiff start may not.

Running only the exhaust fan, 1056Wh divided by 60W gives about 17.6 hours. That is a full summer day of ventilation from a single charge, which is the shape of load this unit fits.

Where it stops#

The capacity is the ceiling. At 1056Wh it holds under one reference day. Every watt-hour the fans use has to come back from the panel that same day, and on a site that goes grey for 48 hours the arithmetic simply fails: two days of load is 2.34kWh against a pack that holds 1056Wh.

One expansion battery takes the pack to 2112Wh, which buys the second day. Beyond that there is no path, and a grower who already knows they need reserve rather than turnaround should read the DELTA 2 Max section instead.

Who should buy it#

Growers whose greenhouse is a fan-and-pump load on a sunny site, who want the smallest unit that reliably ends each day full. Anyone whose weather regularly takes the sun away for more than a day should buy capacity instead of charge speed.

Greenhouses fail on the days the sun does not come out. That is a different problem from the one the C1000 solves, and it is the reason this heavier unit is on the page.

Nearly two days of autonomy, stated plainly#

Our reference greenhouse day, set out in the buying guide, draws about 1.17kWh from the pack. Divide 2048Wh by that and you get 1.75 days. A grower who leaves on Friday evening with a full pack has ventilation and irrigation covered until some time on Sunday even if no sun arrives at all.

The C1000 and the Mega 1, at 1056Wh and 1024Wh, cover about 0.9 of a day each. That is the whole argument for the extra weight.

The refill window is short#

The 1000W solar ceiling is the highest here. Derated to a realistic 80% of rated input, that is 800W of charging. Replacing the 1.17kWh a greenhouse day costs takes about an hour and a half. Refilling the entire 2048Wh pack takes about 2.6 hours.

So this unit does not trade charge speed for capacity, which is the usual compromise. It has more of both than the smaller units, and pays for it in mass.

What the boost figure does not do#

EcoFlow quotes 3400W with X-Boost. That number is reached by lowering the output voltage so current stays within limits, which works for a resistive load like a propagation heat mat and does not work for a motor, which needs the voltage to develop torque.

For an irrigation pump, a circulation pump or an exhaust fan starting under load, the applicable rating is 2400W continuous. That is the highest continuous rating on this shortlist, so this is a caution rather than a disqualification. What it does mean is that the margin a stalled motor has to fit inside is narrower than the 3400W headline suggests, and narrower than the 4500W the Mega 1 quotes as a surge on its normal output.

The weight problem#

Fifty point seven pounds for 2048Wh is 40.4Wh per pound. The S2000 delivers 56.3. Practically, that means the DELTA 2 Max is 15 lb heavier for 38Wh more storage, and it stops being a unit you move. In a greenhouse that is often fine, because it is going to sit on a shelf under the bench all season. It is not fine if you wanted one battery shared between the greenhouse, a shed and a camping trip.

Who should buy it#

Anyone whose weather is the constraint, and anyone who expects the load to grow. The expansion path to 6kWh is the only route here to a pack that can hold a week of winter ventilation. Growers on reliably sunny sites are paying for reserve they will never draw on.

Every other unit here is chosen for how it stores or replaces energy. This one is chosen for a single moment: the fraction of a second when a pump motor tries to start.

Why inrush is the greenhouse failure mode#

An irrigation or booster pump draws several times its running current at the instant it starts, while the motor is stalled and generating no back-EMF. A pump whose plate says 400W can ask for well over a kilowatt for a moment. Under an undersized inverter the unit protects itself, shuts down, and the watering cycle silently does not happen. In a greenhouse in July, that is a crop.

The Mega 1’s 2000W continuous and 4500W surge is a 2.25 times ratio, the widest here, and the S2000’s 3000W peak against 1500W is 2.0. The DELTA 2 Max carries a higher continuous rating at 2400W, but its second figure of 3400W is X-Boost, which reaches that number by lowering voltage and so does nothing for a motor, and the C1000’s 2400W SurgePad works the same way. Set the boost-mode figures aside and the Mega 1 is the only unit here quoting more than twice its continuous rating as a surge on its normal output.

The pack is the compromise#

At 1024Wh this is the smallest battery on the page. Against our 1.17kWh reference greenhouse day, it holds about 0.87 of a day. Running only a 60W exhaust fan it gives about 17.1 hours, and 1024Wh across 27.8 lb is 36.8Wh per pound, the lowest density here.

So this is not a reserve battery. It is a pump starter with a day’s fan energy attached, and it is bought by growers who already know their motor is the problem.

Charging around a watering schedule#

Thirty-six minutes to 80% on AC is the fastest AC top-up here, and 26 minutes with AC and solar together is faster still. For a greenhouse close enough to the house to run a cord, or one that shares a generator with a workshop, that turnaround matters more than capacity does, because the pack is never far from full.

What we cannot tell you is how it behaves on solar alone. The specification set we hold does not publish a maximum solar input, so we will not estimate one. If your greenhouse has no other charging source, that gap should send you to the C1000 or the DELTA 2 Max instead.

Who should buy it#

Growers with a pump that has already failed to start on something smaller, who have mains or generator access nearby, and who can add the B2 batteries later if the load grows. Anyone charging purely from a panel should choose a unit that publishes what its array can be.

Daily cycling is what separates a greenhouse from almost every other use of a portable power station. A home backup unit might see thirty cycles a year. A greenhouse pack sees 365. That single fact changes which specification matters most.

Cycle life, converted into years#

Rated cycle counts are usually printed and ignored. Convert them and they become the most decisive number on the page.

Ten thousand cycles at 2010Wh is roughly 20,100kWh of energy through the pack before it is rated down to 80% of its original capacity. Our reference greenhouse day draws about 1.17kWh. That is more than 17,000 days of use.

For comparison, on the same daily load the C1000’s 3,000 cycles across 1056Wh works out at roughly seven and a half years, the Mega 1’s 3,500 cycles at about eight and a half, and the DELTA 2 Max’s 3,000 cycles across 2048Wh at about fourteen. The honest conclusion is not that this unit lasts half a century. It is that the battery stops being the part that wears out first, which is not true of any other unit here.

What you give up for it#

Four hundred watts of solar input. Derate that to 80% of rated and you are charging at about 320W. Replacing the day’s 1.17kWh takes roughly 3.7 hours of strong sun, and refilling the full 2010Wh pack takes about 6.3 hours.

In July on a clear site that is fine, because the pack starts most mornings only part-empty. In a cloudy week it is the whole problem. Two grey days ask 2.34kWh of a 2010Wh pack, so it is flat before the second one ends, and the clear day that follows has to put back the full 2010Wh and cover its own 1.17kWh on top. At 320W that is close to ten hours of strong sun. The DELTA 2 Max, at 1000W in and therefore about 800W after derating, banks the same energy in about four hours.

The missing 12V port#

Worth flagging because it is specific to this application. Greenhouse kit is full of 12V devices: circulation fans, drip timers, vent openers, soil probes. Most units let you run those straight off a DC port. This one has eight outlets and no 12V DC output, so every one of those loads goes through the inverter and a wall-wart, adding conversion losses to exactly the small, always-on draws you were trying to keep cheap.

Who should buy it#

Growers who are sure of their site and sure of their load, who want to buy once. Anyone whose weather is unreliable, or who wants to run heat mats or a dehumidifier alongside the fans, is better served by the 2400W and 1000W solar input of the DELTA 2 Max.