Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

How much load can be served from 1m² of sunlight

medium.com

Post reply on HN
Print view View original

101–110 of 141 posts

Re: How much load can be served from 1m² of sunlight

#101

Post by Robotbeat »

Of course, you can juice this a bit by doing two things: 1) using concentrating photovoltaics with multifunction solar cells to achieve ~30-40% efficiency. (This requires active cooling.) 2) use 2 axis tracking. 3) solar cells on the back of your array. (Bifacial solar arrays do this in an integrated manner but aren’t concentrating.)

These three together give you on the order of a factor of 3 greater total energy. (Note: concentrating buys you about 20% greater raw efficiency BUT means capturing diffuse light basically doesn’t happen. Might be better off with a non-concentrating bifacial multijunction panel that is still two axis tracked. Concentrators can still help financially because multijunction solar panels are EXPENSIVE.)

Also, if your laptop already has a beefy battery, you don’t need a separate battery. You’ll need a custom MPPT with the right output voltage, but you could hook it straight into your laptop. That saves money (potentially) and a lot of inefficiency.

Re: How much load can be served from 1m² of sunlight

#102

Post by kempbellt »

londons_explore wrote: post #60
danuker wrote: post #2

Rather than inverting 12V DC to 240V AC and back, you could skip a step and use a laptop car charger, converting 12V DC straight to ~20V DC.

A very cheap, bad-practice, but effective solution is to run the inverter to AC and back to DC again with the ATX power supply, but to connect the 12V from the battery direct to the motherboards 12v rail. The motherboard uses most of its power from the 12v rail, and due to the galvanic isolation in the ATX power supply, it should be safe to do. The 12VDC from the battery may not be in spec for the motherboard, but ty…

It's also worth noting that many "12 volt" DC batteries do not store and output at exactly 12 volts.

Depending on the tolerances of your board, you might want to throw a buck converter in the circuit and set the output voltage set to exactly 12 volts to account for any potential over-voltage coming from the battery/panel setup.

They are pretty cheap if you want to DIY (7 for $10 on Amazon). Worth the peace of mind, imo.

I imagine this is what most car-laptop chargers are, but with branded packaging.

Re: How much load can be served from 1m² of sunlight

#103

Post by jtbayly »

fragmede wrote: post #79
Ballas wrote: post #55

Earlier quoted context omitted.

> run on intel only How does that work on a Ryzen laptop?

The English doesn't (quite work), but Intel here refers to the integrated, power-thrifty GPU, so could be more pedantically stated as "run on integrated graphics chip and turn off the Nvidia discrete GPU (and save power)" instead.

I think you may have missed the point. It's Ryzen, meaning AMD, not Intel.

Re: How much load can be served from 1m² of sunlight

#105

Post by forkfork »

jakogut wrote: post #9

> With an idle load, this particular laptop draws 14W of power with the screen turned off. That's an extremely high idle power usage, I also have a laptop with a Ryzen 9 4900HS (the ROG Zephyrus G14, the only laptop with this chip, to my knowledge), and it idles around 9-11W with the screen on . Most of that is actually because of the RTX 2060 that's bundled with it, and won't turn off in Linux because Nvidia doesn't…

Author here, you are correct, not tuned.

Will try your suggestions! Much appreciated.

Re: How much load can be served from 1m² of sunlight

#106

Post by forkfork »

rexreed wrote: post #36
jacob019 wrote: post #10

You won't get 200W from a 200W panel in direct sunlight, but it will still generate some watts at other times, so it should work out. "A 4.6b year old yellow dwarf as a light source" loved that

I thought that was factored in when he talked about 3 full-hours of 200W across the full day? The day in Australia is certainly longer than 3 hours, so I figured that accounted for panel inefficiencies, indirect sunlight, and other such things. But could be wrong. Not sure how the 3 hours was calculated, but I am sure some solar calculators will take your location, average annual sunlight, efficiency and spit out an…

3 hours comes from averaging the daily power generation my Victron MPPT reports. I’m using a 200 watt panel and it reports and average of 600Wh since I set it up a month ago.

Re: How much load can be served from 1m² of sunlight

#107

Post by forkfork »

lmilcin wrote: post #6
PragmaticPulp wrote: post #3

Obviously there is infinite room for optimization of this problem, but this was a fun blog post. I’m interested to see where the author goes with the series.

It is interesting concept for a blog post but ruined by very inefficient implementation. I would expect orders of magnitude more work done on ~20W. Also parsing a compressed 10MB JSON seems like an unusual request. It would maybe be more fun to put a Hello World or Pet Store and get some numbers that will be more relatable to a regular developer.

Intentionally inefficient. I’ve seen a number of my customers doing this pattern, working with ~10 meg JSON for the model layer.

Inefficient but not unrealistic outside of FAANG.

Re: How much load can be served from 1m² of sunlight

#108

Post by forkfork »

bo1024 wrote: post #88
ketralnis wrote: post #83

The armchairs here are all great. If they used a raspberry pi and rewrote their javascript in ARM assembly and reinvented a more power-efficient compression algorithm and solved your favourite problem of serving static pages instead of the problem they actually want to solve, they could maybe get more instructions per watt. But really, I'm glad that they're actually doing it instead of talking about doing it and spen…

I was confused about the "doing it" part. I see that they have all the materials and got some numbers like average power consumption, but they didn't seem to actually set it up and see how it worked?

Author here - I’m learning as I go. I thought of talking a out the actual sunlight starting at closer to 1300W and losing efficiency at each step, but I don’t get have the right tools to do that properly.

I’d def love to hear your suggestions though as I continue to iterate this one.

Re: How much load can be served from 1m² of sunlight

#109

Post by rexreed »

forkfork wrote: post #106
rexreed wrote: post #36

Earlier quoted context omitted.

I thought that was factored in when he talked about 3 full-hours of 200W across the full day? The day in Australia is certainly longer than 3 hours, so I figured that accounted for panel inefficiencies, indirect sunlight, and other such things. But could be wrong. Not sure how the 3 hours was calculated, but I am sure some solar calculators will take your location, average annual sunlight, efficiency and spit out an…

3 hours comes from averaging the daily power generation my Victron MPPT reports. I’m using a 200 watt panel and it reports and average of 600Wh since I set it up a month ago.

Even better than a calculator - it's your actual experience ;)

Re: How much load can be served from 1m² of sunlight

#110

Post by forkfork »

marcosdumay wrote: post #56
lxe wrote: post #49

Technically, it should be "200 watts". The losses happen due to all the inversion and conversion (I think... right?)

TLDR (although it's quite short), he got 21W. The largest factor is the day-cycle. He gets 3 hours equivalent of Sun light a day. I really expected Australia to be more sunny than that.

Mostly clouds and rain bring this down to 600Wh/day. Washed the bird poo off the panel to get an extra 2 watts.
Post reply on HN