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

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

#181

Post by mindslight »

kogepathic wrote: post #153

The author's calculations for the capacity of the battery are very wrong and the battery will not last many years the way he's using it. Deep cycle lead-acid batteries should not be discharged below 50% (known as Depth of Discharge, or DoD) unless you really want to kill them quickly. The author's calculations assume he can drain the battery 100% (35Ah), which while technically correct, will kill his battery very qui…

To be fair, the DoD vs cycle numbers aren't as dire as they first look. Even an ideal deep-discharge battery would have a 1/x curve, as the real metric is total energy stored, which is proportional to DoD*ncycles vs DoD.

For instance, for the two datapoints you gave. At 50% DoD, the battery will have stored 1500 times its capacity over its life. At 90% DoD, the battery will have stored 1350 times its capacity over its life. This is only a 10% degradation.

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

#182

Post by 35bge57dtjku »

dragonwriter wrote: post #92
35bge57dtjku wrote: post #88

Earlier quoted context omitted.

Not if you want to avoid stealing.

Using means not permitted by the law and your contract with the service provider to (attempt to, at any rate) reduce your utility bill would seem to be stealing.

No, it would be breaking an agreement or somesuch. If you're generating your own power you're not taking anything from anyone else, so it's not stealing.

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

#184

Post by sitkack »

nikodunk wrote: post #137
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.

Okay I'm gonna have to look up a mate who works in statics – not sure what to believe from the discussion below (good sources on both sides) :). My gut says it wouldn't move either, but I'm not about to gamble with others' lives. In the meantime, I'll weigh down the four corners with massive cinder blocks (so as not to block sunlight).

Awesome

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

#185

Post by sitkack »

quickben wrote: post #178
Retric wrote: post #149

Earlier quoted context omitted.

No, I have no problem saying securing stuff is generally a good idea. If nothing else it makes it harder for someone to steal it. My point is the specific bad thing described is unlikely to happen. And sure I got a lot of knee jerk reactions but nobody actually did any kind of meaningful calculation demonstrating an issue.

It's not a knee jerk reaction. You have limited view of the problem. I've lived next to a three building being constructed as a kid. The amount of stuff flying is unreal. You aren't accounting for cats, earthquakes, determined birds, malicious intent, gravel under the panel+wind, strong rain that may move the board and angle it. Your sole argument is, historical wind speeds won't lift it. That is not realistic, naive…

Thank you for trying to reach this person. I think they perceive the safety recommendation as a direct attack on logic and mathematics.

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

#187

Post by taneq »

winter_blue wrote: post #70

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.

> It draws circa 100 W when charged via the slow charger that you plug in to an outlet.

1kW - 2kW, surely? 100W would take days to charge.

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

#188

Post by Retric »

sitkack wrote: post #185
quickben wrote: post #178

Earlier quoted context omitted.

It's not a knee jerk reaction. You have limited view of the problem. I've lived next to a three building being constructed as a kid. The amount of stuff flying is unreal. You aren't accounting for cats, earthquakes, determined birds, malicious intent, gravel under the panel+wind, strong rain that may move the board and angle it. Your sole argument is, historical wind speeds won't lift it. That is not realistic, naive…

Thank you for trying to reach this person. I think they perceive the safety recommendation as a direct attack on logic and mathematics.

Ehh, I just said I had no problem tying something down. Especially in earthquake country. Just that wind was unlikely to lift a panel, but rather than admit they where wrong everyone keeps doubling down as if wind where the only issue.

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

#189

Post by Retric »

quickben wrote: post #178
Retric wrote: post #149

Earlier quoted context omitted.

No, I have no problem saying securing stuff is generally a good idea. If nothing else it makes it harder for someone to steal it. My point is the specific bad thing described is unlikely to happen. And sure I got a lot of knee jerk reactions but nobody actually did any kind of meaningful calculation demonstrating an issue.

It's not a knee jerk reaction. You have limited view of the problem. I've lived next to a three building being constructed as a kid. The amount of stuff flying is unreal. You aren't accounting for cats, earthquakes, determined birds, malicious intent, gravel under the panel+wind, strong rain that may move the board and angle it. Your sole argument is, historical wind speeds won't lift it. That is not realistic, naive…

>It's not a knee jerk reaction.

Followed by a knee jerk reaction without any facts backing it up...

> That is not realistic, naive and outright dangerous thing for which people actually get badly hurt or die.

PS: Potted plants are often placed on the top of flat roofs with a lip and don't get tossed off it by the wind. The reason has to do with how the wind is deflected over the building and the obstructions around it. Often pushing them in opposite directions from the wind because of a giant counter rotating vortex of air. But, be happy with your inaccurate and over simplified model of how the world works.

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

#190

Post by galdosdi »

JumpCrisscross wrote: post #124
galdosdi wrote: post #42

Earlier quoted context omitted.

Being able to sell the system is irrelevant as long as the system will last indefinitely (or say, 30 years, which approximates the same value anyway). Everything but the battery is solid state and should last indefinitely -- or certainly more than 8 years. I already excluded the battery as a consumable to calculate the 13% rate of return. But one thing you are right about is the other parts will fail eventually, drag…

> as long as we believe we are right and the market is wrong about the likely future earnings In a liquid market like the stock market, the odds of this being true is small. Recognizing a 10% return against a stock that's crashed 50% borders on, depending on if you're investing your money or others', delusion and fraud, respectively. There is no liquid secondary market for home-solar components, however, so approxima…

Yup, it's very hard to make a good return in the competitive stock market, but easy to make a good return in the market you have exclusive monopoly access to: making investments that cut your own personal costs of living
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