Do you think solar will ever be a practical alternative to batteries?

#1

I own solar panels and batteries and I look at their weight and volume, and overall I feel solar is not worthwhile for most folks.

An example is with Anker of the 21W panel. That is 21W from the solar panels, it then passes through regulators to become 5V 3A theoretically but more usually 2A.

Then that that is in strong direct sunshine. You either take the solar panel out in strong sunshine and point directly to the sun and so be getting 2A output or be leaving it pointed in a general direction so it peaks at 2A but then be lower before/after related to sun angle.

So then you’re talking say 1Amp as an assumed bright day, generally pointing to the sun, average.

Then you’re comparing to mains power, which is say a Powerport2 or Powerport5 which is 2A-2.4A.

Then compare the weights. A 2A output (sunny conditions, pointed at the sun) panel weighs about the same as 20Ah battery, so needs about 10 hours of that condition (sunny, pointed to sun) to make the same power from sun for the same weight as a battery.

So that means you’re talking multi-days, a week, weeks, and/or sunny, to make solar viable relative to batteries.

So is solar worth it?

Trips it suits?

(weeks off grid, days in sunny climes)

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#2

How new is your solar gear? There have been great leaps forward in PV technology in the last few years. I believe it’s now up to 30℅ efficiency.

I would like to see more use of a transparent PV layer. Car roofs and phone screens especially.

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#3

Efficiency is the electron mobile layer. A 21W panel is using that assumed 30% efficiency. Then it downgrades from there through the …

Go put a meter on a solar panel.

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#4

I don’t know if you can really judge the practicality of two wildly different technologies by their ‘weight’ and outputs per se. Solar definitely has its uses as do battery packs. In some cases they go hand in hand. Such as when you need reliable power, you hook up a solar panel to charge the batteries so you can still have electricity without solar.

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#5

Solar is good in theory, but as pointed out by @nigelhealy is terribly inefficient. I live in MN and we’re seeing some solar array farms popup all of a sudden. I can only assume that these are heavily subsidized by the government, because I don’t see how it can make economic sense otherwise. With our very low sun angle in the fall-winter-spring it seems like a losing proposition.

Now if they put all of these solar arrays on top of the neighborhood Walmart, Target, Home Depot, etc. I’d have less problem with it. At least then your not using up good farmland, etc.

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#6

Solar makes most sense for static situations, where you lug all of the weight and leave it there for years.

Solar for portable is where I challenge its efficacy.

You can get in strong sunshine a decent 1A output, in perfect conditions I see 2A output. That is very useful, so its just matter of how many days of sunshine are you expecting, the length of the trip, etc.

So say it was somewhere I’d expect sunny at least half the time and I was at least a 5 days off-grid trip, then I’d take solar.

A 21W is a sweetspot with most modern devices because it produce 1A-2W output is fairly in balance with the input capability of the device attached. If you are moving a lot with the solar panel, it will tend to be unfolded at stops so breakfast/lunch/evening type of which lunch is the strongest sunshine and evening probably the longest time, so you’d like connect your device (mobile say) directly to the solar panel, and most mobiles struggle to take more than 1A-2A anyway, particularly if you are using the device at the same time (thermal throttling causes battery recharging to be reduced if the cpu/gpu is busy serving you).

In a more static situation you’d likely not leave devices attached but use batteries with solar then use those batteries overnight, then batteries are more capable of higher input current, then large solar panels pointed south tilted to latitude would another sweetspot, so two 21W panels each with say a 13000mah attached.

So I think the current portable solar devices are about well balance with use cases, and they are fairly affordable, my 21W panel I paid $43 a year ago. I’d expect solar panel efficiency to nudge slowly so most of the change will be the cost dropping.

#7

I don’t, because modern smartphones that have Quick Charge are requiring more and more amps to be charged. I just don’t think the sun will ever be able to provide enough power to quickly and efficiently charge a device.

#8

Quick Charge has little to do with this topic of solar.

Batteries have more of an ingest capability when less charged than when more charged. That is exploited by technologies to boost the charging of mobiles when less charged.

A mains powered charger is able to ingest higher power to feed a low charge battery and then reduce the ingest and output to match a battery.

A solar panel has a fixed input which cannot be increased to match a battery’s ingest capability.

This is best moved to basic electrics and not text waffle.

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