The Grid Doctor 300 is a small plug-in battery: 300 watts out, 320 watt-hours stored, $497 with one 100W panel on My Patriot Supply's page (read 2026-11-04). It suits a phone, a router, lamps and a CPAP for a night. It does not suit a full-size refrigerator, and the seller says so itself.
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How to read this review
This is a spec-and-fit review. We did not test, own or use the unit. Every number about what the unit is rated to do comes from My Patriot Supply's product page, read on 2026-11-04, and is attributed to the seller. Every runtime we calculate ourselves is labelled as an estimate, with the arithmetic shown, so you can swap in your own appliance's watts. If you are still choosing between sizes, start with the main guide to the best portable power station for home backup and come back here.
Spec table
| Item | What the seller's page lists |
|---|---|
| Price (read 2026-11-04) | $497, includes one 100W solar panel |
| Output | 300W continuous, 600W surge, pure sine wave |
| Stored energy | 320Wh, LiFePO4 chemistry |
| Weight | 8.625 lb; 9.5 x 7.3 x 5.5 in |
| Ports | 9 in total, including two AC outlets, USB-A, USB-C (30W out; 60W in and out) and 12V DC |
| Wall charging | 80W adapter |
| Solar | One 100W panel included (IP65, 9.8 lb); one more 100W panel allowed, so 200W at most |
| Extra panel (read 2026-11-04) | $247 for another 100W |
| Operating temperature | 14 to 104 F |
| Stacking | Units can be stacked for more capacity, each operating independently |
Price per watt-hour, our arithmetic: $497 divided by 320Wh is about $1.55 per Wh with the panel included. The larger unit works out lower; the head-to-head page lays the two side by side.
What it can run
Two figures matter. Watts decide whether the unit can power a device at all: anything that draws more than 300W running, or whose start-up surge goes past 600W, is out. Watt-hours decide for how long. The formula we use throughout the site is hours = Wh x 0.85 / watts, where 0.85 is our own planning assumption for conversion losses. The ideal ceiling, with no losses, is Wh divided by watts.
The watts below are illustrative assumptions, not sourced facts. Read the rating label on your own device.
| Load (assumed watts) | Ideal hours | Planning hours (x 0.85) | Within 300W? |
|---|---|---|---|
| Wi-Fi router (10W) | 32.0 | 27.2 | Yes |
| Four LED bulbs (40W) | 8.0 | 6.8 | Yes |
| CPAP, no humidifier (40W) | 8.0 | 6.8 | Yes |
| 42-inch LED TV (80W) | 4.0 | 3.4 | Yes |
| Mini refrigerator (80W) | 4.0 | 3.4 | Yes |
| Full-size refrigerator, average running draw (150W) | 2.1 | 1.8 | Running only; start-up surge unchecked |
| Gas furnace blower (400W) | 0.8 | 0.7 | No, above 300W |
| Sump pump, running (800W) | 0.4 | 0.3 | No, above 300W |
The seller's runtimes next to ours
The seller's page lists these runtimes for the 300: a CPAP up to 8 hours, a Wi-Fi router up to 16 hours, a mini refrigerator (1.5 cubic feet) up to 4 hours, a 42-inch TV up to 4 hours, a 60W lamp up to 5 hours and a box fan up to 5 hours. It also lists up to 20 smartphone recharges and up to 6 laptop recharges.
Ours differ for a plain reason: the seller does not print the wattage it assumed. Our router figure is longer than the seller's because we assumed 10W; a router drawing 20W would land near the seller's 16 hours. Our CPAP ideal figure of 8.0 hours matches the seller's only because we assumed 40W. Treat the seller's numbers as ceilings and your own label as the input that counts.
Charging
The seller lists three ways to refill the 300: the 80W wall adapter, solar, and a car port. Our arithmetic, with no losses counted: 320Wh at 80W is about 4 hours from empty at the adapter's rated input. On solar, one 100W panel in five good sun hours would give 500Wh on paper, more than the battery holds; with real-world haze, angle and cable losses the figure is lower, and the two-panel limit of 200W only helps if you have the sun. Those are estimates, not seller figures.
If you plan to run it every night of an outage, the charging side matters as much as the 320Wh. Our guide to choosing a solar generator for home backup works through the panel math.
The cycle-life conflict
The seller's page says 2,000+ cycles in the specification list, with 800 cycles to 80% capacity noted beside it. The technology blurb on the same page says 3,500. The seller's page says one thing in one place and another in another, and we cannot tell which describes the product, so we print both. A "cycle" is one full discharge and recharge; the page does not say how the figure was measured. Our guide on how long these units last explains why the 800-cycles-to-80% line is the more conservative reading to plan around.
The seller's review figure
On 2026-11-04 the seller's page showed a 4.7 rating from 148 reviews, with 128 of them five-star and 7 one-star. That is the seller's own display, dated and attributed; we did not collect or verify the reviews, and we use no rating markup on this site.
Limits to know before you buy
My Patriot Supply says the 300 is not designed for full-size refrigerators, microwaves, sump pumps, space heaters or HVAC. Our numbers agree: a full-size fridge on this unit gives under two hours on paper, and the furnace blower and sump pump examples exceed the 300W output.
A few practical limits follow from the spec:
- It is plug-in power, not a home system. Do not plug a power station into a wall outlet to power the house. Run cords from the unit to the device.
- Motors surge. A fridge compressor or pump can draw several times its running watts for a moment. Check surge against the 600W rating.
- Medical devices. If you plan to run a CPAP, read the watts on its label and manual, remember that a humidifier or heated hose raises the draw, and ask your clinician about an outage plan. Ready.gov advises talking to your medical provider about backup for electrically powered medical devices. Our CPAP sizing guide shows the arithmetic.
- Fridges. Ready.gov and food-safety guidance say a closed refrigerator keeps food cold for about 4 hours; see our refrigerator runtime math for what 320Wh does and does not buy you.
If your load list is longer than a few small devices, total it first with the watts to run a house guide.
Who should skip it
Skip the 300 if your must-run list includes a refrigerator, a sump pump, a furnace blower or anything on 240V. The step up in the seller's range is the Grid Doctor 3300, covered in our 3300 vs 300 comparison: 2,048Wh and 3,300W, at $2,997 with a 200W panel. A 3,300W unit also has limits: the seller says it is not meant for 240V loads.
A good fit
- A phone, a laptop, a router and a lamp through a short outage
- A CPAP for a night, after you check the watts on your own machine
- A small, 8.625 lb backup you can carry from room to room
FAQ
How many watts is the Grid Doctor 300?
The seller's page lists 300W continuous and 600W surge, pure sine wave, with 320Wh of LiFePO4 storage.
Can the Grid Doctor 300 run a refrigerator?
The seller says it is not designed for full-size refrigerators. A mini refrigerator is listed at up to 4 hours. Our arithmetic gives a full-size fridge under two hours at an assumed 150W, before counting the start-up surge.
How long will it run a CPAP?
The seller says up to about 8 hours. Check the watts printed on your machine, include any humidifier or heated hose, and use hours = Wh x 0.85 / watts. Ask your clinician about your own outage plan.
What does it cost?
The seller's page showed $497 with one 100W panel on 2026-11-04. An extra 100W panel was $247. Check the live page, because prices change.
Is it safe to use indoors?
The seller says it can be used indoors because it has no combustion. Keep it ventilated while charging, use only cables the manual approves, and read the manual. We have not seen a safety certification for it and do not claim one.
Related guides
Sources
- My Patriot Supply, Grid Doctor 300 product page, read 2026-11-04: https://www.mypatriotsupply.com/products/solar-generator-300w-by-grid-doctor
- Ready.gov, Power Outages, read 2026-11-04: https://www.ready.gov/power-outages
- FoodSafety.gov, Food Safety During a Power Outage, read 2026-11-04: https://www.foodsafety.gov/food-safety-charts/food-safety-during-power-outage
Update history
| Date | Change |
|---|---|
| 2026-11-04 | First published |