Low PV charging

I am using 2 24V Newpowa 210 Watt solar panels in series. I get 360 + watts of power on a clear day, but my Ac200p only went from 8% to 23% battery in 2 1/2 hours. This seems much less than I expected. Why is the charging so low? I can charge this unit in about 3 hours plugged in at 450 watts but solar isn’t recharging the battery back. This is a problem.

My first thought is that if you are getting around 360 watts of power on a clear day then your “clear” day sun conditions are not lasting long or the timeframe you mention you are charging that you are not getting 360 watts. You would need around 6 hours or so of those perfect conditions to fully charge. I would suggest closer monitoring of the incoming charging watage and see if the 360 watts is constant or comes and goes bases on a cloud or any shading. The panels also have to be appropriately aligned with the sun and this position changes throughout the day.

You state you can charge the AC200 when plugged in (to AC?) in 3 hours but that would have to be at a greater than 0% battery condition at the beginning of the charge.

Lastly, you did not state if you are using any outgoing power (load) during the solar charging. This will affect your charge time as well. Your fastest charging will occur with the AC and DC outputs in the Off position.

My first test was with load. I had my kitchen refrigerator plugged in. It was pulling from 0 - 120 watts but mostly between 86 -120 Watts. Add to that the inverter inefficiency and it adds up. Also, the panels are not properly aligned as I hoped to recreate real world conditions for a van rooftop mount.
I did another test without load and AC and DC both off. The sky was perfectly clear and the AC200P went from 19% to 44%. I also have blockage as the house shades the panels until 11- 11:30 AM, but I can’t expect more than an additional 20% if I had all morning hours. Also, it is winter.
Still, I expected more charging than I got. I guess I should have done more math rather than spend money first. I was hoping to have the AC200P fully charged on a daily basis. 4 panels with series pairs in parallel seems to be a minimum requirement. That’s going to take up all my roof space. Or, mount one pair on the side of the van lengthwise with the ability to lift out to angle with rooftop mounted lengthwise and able to lift to angle leaving half of one side of the roof for exhaust fans and such. Just make sure the van is facing parallel the sun path. Charging while traveling is not recommended anyway.

Any small amount of shading on any panel will dramatically affect the total output. The new Bluetti PV series panels are a good choice if shading is an issue as they only cut out the amount of power in rough comparison to the % of panels shaded.

I need something that withstands weather and hale. The suitcase panels I’ve seen just don’t fit the bill for permanent outdoor mounting. I wish they did.

No matter what you do, shading any part of any panel will drop the rate of charge far more than the amount shaded. Good angle and proper sunlight are critical for max charge rates.


I’ve just discovered how true that is. My panels were getting shade, very LITTLE shade at all but it made a big difference. With only a small corner of one panel between the two shaded I was getting 70 watts at 36deg angle at 12:45PM. I then set the panels flat with no shade at all and the watts immediately jumped to 240.

I did read about panels that were built to minimize the effect of shaded cells but my Newpowa panels are very susceptible and obviously weren’t made that way.

I’m glad to discover this though because it means my plan to mount them flat on a van rooftop is still valid. I’ll post results of a full day of sun the next time I have one.

Roof top will work, but they are still subject to shading depending on where parked.

At least you can move the van, unlike moving your house =)

New results! My Bluetti AC200P went from 62% charge to 99% with my panels laid flat with no portion of shadow. This is with full sun starting between 11 - 11:30 am until 3pm. Prior to that, the panels were shaded by the house, so I do not have the benefit of morning hours. At 3pm the Bluetti reported between 20 - 30 watts charge so I don’t expect to gain much from the rest of the daylight hours.
I think with full morning to sunset I could expect a 70% charge with these 2 24v panels laying flat. I will investigate angling and solar concentration with reflective panels next.

I’m much happier with my purchases now.

See, now you understand why they are called “solar panels” and not light absorbing thingys. Best results always are from the panel angled to point straight toward the sun source with no shading on any part of the panel and with the sun at the highest point of the day.

Yes, angling to be perpendicular is ideal, but avoiding shading is often more critical.

Yes it is, because solar panels must be exposed to direct sunlight in order to efficiently produce electrical currant.