Awhile back several members including myself engaged in a good discussion around Solar. Awhile back being 2017. You can find the thread here.

https://sigforum.com/eve/forum...935/m/9140038034/p/1 https://sigforum.com/eve/forum...935/m/9140038034/p/1

I asked Chat to summarize and modernize since tech has changed a lot in nearly 9 years. Here is a summary of that post on portable solar.

Portable Solar Panels & Battery Charging (2026 Update)

The old thread still has good advice, but portable solar has improved a lot. USB-C PD, LiFePO₄ batteries, MPPT controllers, and portable power stations have become the standard.

The basic principles haven't changed.

1. Think in Watt-hours (Wh), not mAh

Solar panels produce watts (W), while batteries store watt-hours (Wh).

Wh = Volts × Amp-hours

Example:

20,000 mAh battery

20 Ah × 3.7 V ≈ 74 Wh

A battery bank won't deliver all 74 Wh because of charging and conversion losses. Plan on roughly 80–90% usable energy.

2. Figure out your daily energy needs

Add up everything you want to charge.

Example:

Phone = 15 Wh
Tablet = 30 Wh
Flashlights = 10 Wh

Total = 55 Wh/day

For devices that list watts instead:

Energy (Wh) = Watts × Hours Used

3. Size your panel using Peak Sun Hours

Don't use daylight hours.

Use:

Panel Size = Daily Wh ÷ Peak Sun Hours ÷ System Efficiency

Example:

Need 100 Wh/day

4 Peak Sun Hours

75% efficiency

100 ÷ 4 ÷ 0.75 = 33W minimum

I'd buy at least a 50–100W panel to provide margin for clouds, heat, poor panel angle, and seasonal changes.

4. Expect real-world losses

A simple planning equation is:

Daily Solar Production ≈ Panel Watts × Peak Sun Hours × 0.7–0.8

Example:

100W panel

4 Peak Sun Hours

100 × 4 × 0.75 = 300 Wh/day

The biggest losses come from:

Panel temperature
Poor sun angle
Clouds
Partial shade
Battery charging
Voltage conversion

5. Charge a battery—not your phone

Instead of:

Solar → Phone

Use:

Solar → Battery Bank/Power Station → Phone

The battery acts as a buffer, allowing your panel to collect energy throughout the day while providing stable power to your devices whenever you need it.

6. Avoid unnecessary conversions

More conversions = more losses.

Best:

Solar → Battery → USB-C Device

Less efficient:

Solar → Battery → Inverter → Wall Charger → Device

Only use the inverter when you actually need AC power.

7. MPPT is worth it

Modern MPPT charge controllers harvest more energy than older PWM controllers, especially in changing weather and cooler temperatures.

Most quality portable power stations already include an MPPT controller.

8. Buy enough solar

The #1 mistake is buying the smallest panel that works on paper.

I'd rather have extra charging capacity than spend all day chasing sunlight.

If the math says you need 60W, I'd probably buy a 100W panel.

If it says 150W, I'd probably buy 200W.

9. Buy for your use case

Backpacking

20–30k mAh USB-C power bank
40–60W folding panel

Vehicle camping

300–700Wh LiFePO₄ power station
100–200W panel

Home emergency backup

1–3kWh LiFePO₄ power station
400W+ solar

Bottom Line
Calculate your daily Wh usage.
Use Peak Sun Hours, not daylight hours.
Plan on 70–80% real-world solar efficiency.
Charge a battery first, then your devices.
Buy more panel than the math says—you'll almost never regret having extra solar.

I picked up one of these for my get-home bag.
I didn't get chance to mess with it yet and actually see how it does charging - but I do like that you can connect your phone or something directly to it with no intermediary device.

I have a couple 100 watt solar panels from Harbor Freight that work pretty well. They were highly rated so I grabbed them on sale along with a different brand off Amazon. I don't have much illusion of 300 watts worth of panels being of too much use but they'll be of some use if ever needed.

Thought about starting a new thread, but I think this'll fit here.

About the only thing that I am concerned with at this point, should the power go bye-bye, is keeping my freezers running and possibly the fridge. I don't need lights and I don't a TV, so that is the only power that I will truly need.

To that end, I think that I'm going to order up an EcoFlow 4kwh solar generator with a 400w solar panel. My thought is that on a full charge it'll keep my stuff cold/frozen for a couple of days. The bonus of this unit is that I currently have two 200w panels that I can hook into the 400w one and increase my charging speed. Off season or in cloudy conditions, I can charge it up with my Honda generator in about an hour and a half and I keep roughly 50 gallons of gas and 300 gallons+ of propane to run that (not counting the 500g main tank for the house and the 250g one for the shop). So, between the sun and the Honda, I think that I'll be good for a good long while if need be. It's a tad on the spendy side, though, at $3K, but I think that it is a better to have it and not need it sort of thing.

It's a bit early now, but for the past few years Amazon has had some aggressive Holiday sales on Ecoflow and Jackery products. Keep an eye out in November. (I have an Ecoflow 1600W and am thinking about picking up a larger 2nd unit)

If you are a Veteran, you can check Home Depot. I picked up a BLUETTI with solar panel charging. Vets get 10% off every day and a couple times a year they have those type of things as the deal of the day.

Mine is only good for small things, but gets me portable power. My 4Runner already has a 120v outlet and I can charge the BLUETTI off that or the solar panels. I already have a natural gas generator on my house so I do not need anything real large.

A few months back I picked up a 7w HarborTools solar panel that was on clearance for $10.

It will absolutely charge a cell phone and charge the tractor battery.

It's made me rethink solar and what I want to do in the future.
There will be a shooting shack put up at my little range and I'm seriously considering covering the roof in panes.

Maybe 2500 watts to start.