The short answer: the number of panels matters less than their total watts and the sun you get. As a guide, about 800 watts of panels refills a HomePower 3000 in a long sunny day, 400 watts takes a day and a half or more, and in winter or under cloud you should plan on a partial charge. Below is the sum, so you can work it out for your own yard.
The sum, in plain steps
A solar panel is rated in watts, and that is its output in perfect lab light. In a real yard you get less. The sum has three parts:
- The battery size. The HomePower 3000 holds 3,072Wh (watt-hours). That is the amount of energy to put back.
- The real panel output. Take the panel rating and multiply by about 0.7. Heat, angle, dust, cables and the charger all take a cut.
- The hours of strong sun. Not daylight hours, but “full sun equivalent” hours. Most of the US gets roughly 3 to 6 in a day, with summer at the high end and winter at the low end.
Charge time in hours is the battery size divided by the real output. For example, 800W of panels gives about 560W real output. 3,072 divided by 560 is about 5.5 hours of strong light.
These are rough figures. Panel wattage, tilt, shade, latitude and cloud all move them, and the real bundle rating is on the Jackery product page.
Charge time by panel wattage
This table assumes an empty battery and nothing plugged in. Real output is 70 percent of the panel rating.
| Panels (rated) | Real output | Hours of strong sun to fill | Days at 4 sun-hours | Days at 6 sun-hours |
|---|---|---|---|---|
| 200W | 140W | about 22 | 5.5 | 3.7 |
| 400W | 280W | about 11 | 2.7 | 1.8 |
| 600W | 420W | about 7.3 | 1.8 | 1.2 |
| 800W | 560W | about 5.5 | 1.4 | 0.9 |
| 1,200W | 840W | about 3.7 | 0.9 | 0.6 |
A caution on the bottom rows: every unit has a maximum solar input. If your panels can produce more than the unit accepts, the extra is wasted. Check the figure on the product page before buying panels beyond the bundle.
What matters more than the panel count
Season. The same panels that fill the battery in one summer day may give a third of that in December, when the sun is low and the day is short.
Cloud. Heavy overcast can cut output to a small fraction of normal. Plan on the router and phones, not on the fridge and a full recharge.
Angle and shade. Panels flat on the ground lose a lot compared with panels tilted at the sun. A single shadow across one panel can pull the whole string down. Move them once or twice a day.
What is plugged in. Power from the panels goes to your loads first. A fridge uses about 1,000 to 1,500Wh a day, so on a good day that comes out of the panel’s output before anything reaches the battery.
What the panels need to do in an outage
Panels do not have to fill the battery. They only have to put back what you use. Most households in an outage run a short list of essentials:
| Load | Typical use per day |
|---|---|
| Refrigerator | 1,000 to 1,500Wh |
| Wi-Fi router and modem | 400 to 500Wh |
| LED lights, a few rooms | 300 to 400Wh |
| Phones, laptop | 200 to 300Wh |
| CPAP | 300 to 700Wh |
That adds up to roughly 2,000 to 3,000Wh a day for the full list, and about 1,000 to 1,500Wh if you only keep the fridge and the router. Now compare that with what panels deliver:
| Sun-hours in the day | 400W of panels | 800W of panels |
|---|---|---|
| 2 (winter, cloudy) | about 560Wh | about 1,100Wh |
| 4 (typical) | about 1,100Wh | about 2,200Wh |
| 6 (summer) | about 1,700Wh | about 3,400Wh |
So 800W of panels in typical sun more or less covers the full essentials list every day, which means the outage can run on indefinitely. Roughly 400W covers the fridge and router in typical sun but not much more. In deep winter, even 800W only covers the very short list.
Plan for an outage that comes in winter
If your outages are mostly winter storms, do not count on the panels to recharge the battery. Count on the battery.
- Charge to 100 percent from the wall the moment a storm is forecast.
- Cut the list. Fridge, router, phones and one light is about 1.5 to 2kWh a day, and the full 3,072Wh then lasts well over a day with the sun adding what it can.
- Run the fridge in short bursts only if the outage is long. A closed fridge stays cold for roughly four hours without power.
- Use sun while you have it. Set the panels out first thing and bring them in at dusk.
For a longer view, our HomePower 3000 review walks through a two-day outage hour by hour.
Check the current price of the HomePower 3000 bundle
When panels cannot keep up
Some homes need more energy than panels can return, either because the list includes a furnace blower or window air conditioner, or because the outage is in a dark season. The options are:
- More battery. The HomePower 3600 Plus expands up to 21kWh, so a big battery carries you through low-sun days. Compare them in HomePower 3000 vs 3600 Plus vs 5000 Plus.
- A smaller list. Sizing starts with the list. Our sizing guide shows how to build it.
- A fuel backup for long outages. See solar generator vs gas generator for how the two compare, including the carbon monoxide rule that applies to the gas option.
Before you buy panels
- Write down the daily watt-hours of your essentials list.
- Pick the season your outages usually fall in and use its sun-hours, not the summer figure.
- Multiply panel watts by 0.7, then by sun-hours. That is your daily return.
- If the return is less than your daily use, either shorten the list or add battery, not panels.
- Check the unit’s maximum solar input before buying beyond the bundle.
- Find a spot with a clear view of the sun between mid-morning and mid-afternoon.
The pattern is the same everywhere: panels are what keep an outage going, the battery is what gets you through the night and the cloudy days, and the list decides how much of each you need. For the full picture of which unit suits which home, read our national buying guide.