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

Show HN: $200 Solar Self-Sufficiency Without Your Landlord Noticing

medium.com

Post reply on HN
Print view View original

61–70 of 192 posts

Re: Show HN: $200 Solar Self-Sufficiency  Without Your Landlord Noticing

#61

Post by mod »

AnimalMuppet wrote: post #57
grecy wrote: post #33

I built a very similar system into my Jeep-house. I have two 100W panels on the pop-top roof, a charge controller and a dedicated solar battery (isolated from the engine-starting battery) that runs my fridge, water pump, UV treatment lamp, interior lights, air compressor and charges all my electronics (laptop, kindle, cameras, etc.) directly from 12V DC. I can leave the Jeep parked without running the engine for days…

A question: How much did the solar aspects of your rig cost? And a comment: You might want the ability to tap your solar battery to start the Jeep, if you're going to leave it parked that long.

Wouldn't tapping the other battery be a simple matter of a pair of jumper cables?

I mean, I guess it'd be nice to have wired in, but I can't imagine the time-savings would ever catch up to the initial amount of work.

Re: Show HN: $200 Solar Self-Sufficiency  Without Your Landlord Noticing

#62

Post by quickthrower »

Is the flat panel on the roof optimal? Maybe at the equator but on our house we angle them to catch more of the sun throughout the day.

Also I echo sentiments of whether the landlord and/or building supervisor would be happy and also the electrics regulations in your country. It's only 12v but is this legal to hang loose wires down the building?

Re: Show HN: $200 Solar Self-Sufficiency  Without Your Landlord Noticing

#63

Post by Retric »

sitkack wrote: post #54

Please bolt the panel down, if wind picks it up and blows it off the roof it could easily kill someone.

I really doubt the wind is going to pick up a 2'x4' ~20lb panel like that when it's flat on a roof. Now if he had lifted an edge to try and get a better angle with the sun that would IMO be a much larger issue.

Re: Show HN: $200 Solar Self-Sufficiency  Without Your Landlord Noticing

#64

Post by cjonas »

Obvious Problems:

1: You're not using a pure sine wave inverter so right off the back you are losing significant efficiency (Most the things you're charging use DC power anyways so it would be better to just get a nice DC charger).

2: If you are discharging your battery past 50%, you're going to significant reduce it's life span.

Re: Show HN: $200 Solar Self-Sufficiency  Without Your Landlord Noticing

#65

Post by quickthrower »

reaperducer wrote: post #46
mchannon wrote: post #15

Far more cost-effective would have been to skip the battery and just put a cheap chinese pure-sine-wave grid-tie inverter to bridge between the wall outlet and the panel. It's simple- it has a 110V line cord and plugs into the outlet, sending current the opposite way of normal. Do a search on your favorite e-commerce site for "grid tie inverter" and you'll see what I mean. These cheap inverters have most of the same…

The two big reasons not to do this are his own words: "cheap" and "chinese."

Yep it going to be a fire risk.

Re: Show HN: $200 Solar Self-Sufficiency  Without Your Landlord Noticing

#66

Post by AnimalMuppet »

mod wrote: post #61
AnimalMuppet wrote: post #57

Earlier quoted context omitted.

A question: How much did the solar aspects of your rig cost? And a comment: You might want the ability to tap your solar battery to start the Jeep, if you're going to leave it parked that long.

Wouldn't tapping the other battery be a simple matter of a pair of jumper cables? I mean, I guess it'd be nice to have wired in, but I can't imagine the time-savings would ever catch up to the initial amount of work.

Depends on how close the two batteries are to each other.

I mean, I guess you could physically remove the solar battery, and hand-carry it to the ground just in front of the engine compartment, but now the hassle factor is getting rather high...

Re: Show HN: $200 Solar Self-Sufficiency  Without Your Landlord Noticing

#67

Post by matt_wulfeck »

xsmasher wrote: post #30
galdosdi wrote: post #8

Cool! The one thing I notice the author gets wrong is (out of modesty perhaps) claiming the system isn't very financially successful. But it actually is! > 200W system payback period: $300 / $48 = 6.5 years until payback > Either way you cut it, this is not a money saving machine. Energy prices are just too low. That represents like a 16% rate of return with little risk, which any investor would take in a second. How…

Those calculations also assume he'll use all of the energy it produces, every day, with no loss; it's a back-of-envelope best-case calculation, at best.

If we're getting into the nitty-gritty, then let's also include energy cost inflation into the equation. These numbers are for PG&E which is roughly equivalent for SF:

    2001: 0.10c kw/h
    2017: 0.28c kw/h (as per my recent bill)
That's an average of 10% increase in energy cost per year!

https://www.pge.com/tariffs/electric.shtml

Re: Show HN: $200 Solar Self-Sufficiency  Without Your Landlord Noticing

#68

Post by mbreese »

Retric wrote: post #63
sitkack wrote: post #54

Please bolt the panel down, if wind picks it up and blows it off the roof it could easily kill someone.

I really doubt the wind is going to pick up a 2'x4' ~20lb panel like that when it's flat on a roof. Now if he had lifted an edge to try and get a better angle with the sun that would IMO be a much larger issue.

No, that could easily happen. The parent was right, that panel should be secured in some way. Wind gusts can do some crazy things.

Re: Show HN: $200 Solar Self-Sufficiency  Without Your Landlord Noticing

#70

Post by winter_blue »

I wonder if you can mount this over a roof rack for a plug-in hybrid car like he Chevy Volt/Bolt. It'd be an amazing way to charge your car.

Although, 200 W might be a bit too low for the Chevy Volt. It draws circa 100 W when charged via the slow charger that you plug in to an outlet.

Post reply on HN