
Show HN: Build A Personal Power Plant for $200 - nikodunk
http://gridlesskits.com/2017/09/06/burning-man-update.html
======
charlesju
Here is the much more portable and expensive version of this kit.

Anker PowerHouse to store the energy. 400 WH which is about the same capacity
as the deep cycle battery listed, but this is lithium based so it's much
lighter (9.3 lbs vs about 30 lbs for the deep cycle version). $500
[https://www.amazon.com/Anker-PowerHouse-Generator-
Alternativ...](https://www.amazon.com/Anker-PowerHouse-Generator-Alternative-
Rechargeable/dp/B0196GQAKM/ref=sr_1_1?ie=UTF8&qid=1505144286&sr=8-1&keywords=anker+powerhouse+120000)

Foldable 80W solar panel. $190 [https://www.amazon.com/ALLPOWERS-Foldable-
SunPower-Technolog...](https://www.amazon.com/ALLPOWERS-Foldable-SunPower-
Technology-
Notebooks/dp/B01M5DCPKD/ref=pd_sbs_107_1?_encoding=UTF8&psc=1&refRID=AAP7K0VNKBN6G93D6MBR)

Extension cord for solar panel to battery. $8
[https://smile.amazon.com/gp/product/B00FTFYH0U/ref=oh_aui_de...](https://smile.amazon.com/gp/product/B00FTFYH0U/ref=oh_aui_detailpage_o06_s01?ie=UTF8&psc=1)

Evaporative Cooler instead of building your own. $112
[https://smile.amazon.com/gp/product/B007SNQ4FM/ref=oh_aui_de...](https://smile.amazon.com/gp/product/B007SNQ4FM/ref=oh_aui_detailpage_o08_s00?ie=UTF8&psc=1)

$810 for the total package. The benefits are that you get to use a lithium-
based battery which is 20 lbs lighter, you can use a foldable solar panel
which is more portable, and you buy a pre-assembled evaporative cooler which
has nice features like swinging. Mainly this is a good solution for those that
just want to press buttons and set up their configuration in a few hours
otherwise the kit seems like a good option too.

I used this configuration at burning man and the battery was permanently
charged even with the cooler on the whole time. I needed another shade
structure for the tent to keep it down a couple more degrees but I was able to
sleep until noon with this set up and be totally off grid and have enough
power left over for lights and music.

~~~
stevenwoo
Is there a major difference between lithium and deep cycle lead acid batteries
with respect to battery life versus amount of discharge per usage or is it a
wash?

~~~
irq
There are indeed several major differences. The first one that comes to mind
is to get the most cycles out of a lead acid battery, they recommend not
discharging it below 50% capacity. Lithium ion batteries are usually good to
85% - 90% discharge.

~~~
detaro
And on the other hand shouldn't be fully charged. Only going to 90% capacity
does wonders for their lifetime.

~~~
photojosh
Yes, but you're still talking hundreds of charges to 100% for a Li-ion before
you lose capacity. A regular charge to 90% and then only charging to 100% on
the odd occasion you need the little bit extra gives you the best of both
worlds.

Do even a handful of deep discharges on a lead-acid battery and you'll kill
it.

------
okreallywtf
This got mentioned under another comment but it is worth stating at the top
level: always use fuses or breakers in any kind of system, that battery is a
fire/bomb waiting to happen if there is a dead short. Charge controllers can
do this when they fail (I had a 30A MPPT CC do this, and not a cheap one). I
wouldn't sleep next to this thing without it (I didn't look in incredible
detail at their site but a cursory search didn't find anything about current
protection).

DC systems and AC systems also require differently rated components. You
cannot just go buy a 30A 120V AC breaker from home depot for the DC side of
your system. It takes a lot more to disconnect DC than it does in AC (because
AC cycles to 0V 60x/s it doesn't take much of a gap/insulator to break a
connection, DC is not the same. Trying to use a light-switch for a DC light
can result in problems [1].

I've had good luck with midnite products (charge controllers and breakers,
etc) [2]. Their breakers are 100% rated in that if you expect your max current
output to be 30A DC (12v probably), you can use a 30A breaker and not have to
oversize it, they are rated to take the guess work out of how to size your
breakers which is nice.

Edit: I tried to find some info on the CC they use (in case it had internal
protection which I wouldn't trust even if they said it did) and no luck. Given
its pedigree and price (most charge controller add on displays cost more than
this thing) you definitely don't want to take any chances. Price doesn't
always mean quality but there is probably a good reason they are usually more
expensive than this.

[1] [http://blog.gogreensolar.com/2015/02/ac-vs-dc-
breakers.html](http://blog.gogreensolar.com/2015/02/ac-vs-dc-breakers.html)

[2]
[http://www.midnitesolar.com/products.php?menuItem=products&p...](http://www.midnitesolar.com/products.php?menuItem=products&productCat_ID=16&productCatName=)

------
mikestew
I figured this to be some rinky-dink setup with some teensy pocket solar
panel. I mean, $200? Hell, a decent 100W panel will cost you that much.

100W panels are $94 now? Holy crap, if we used more power boondocking I’d
cover the roof of the camper with them. But we don’t use the power we make
now, with a propane-powered refrigerator and LED lighting. And that’s the
problem with solar, it can power the little stuff, like LED lights or a small
invertor, and 100W panels are almost overkill. But get to something like a
fridge or A/C for even a small camper, and one will need multiple panels and a
big set of batteries.

Nice setup, and I wish them well with their turnkey solution.

~~~
tyingq
They mention a swamp cooler in the article, which is surprising. I would
expect those to have a big power hungry fan motor that's too much for the
panel.

They do say it's a DC based swamp cooler. Looks home made though...more detail
on it would be interesting.

~~~
mikestew
After a relatively blistering summer here in Seattle, here’s something I’ve
considered building for when we leave dogs in the camper:
[http://www.mdpub.com/swampcooler/index.html](http://www.mdpub.com/swampcooler/index.html).
Eight watts for the fans, and the bird bath pump can’t be but a couple of
watts. Easily done with a 100W panel, should be able to run overnight with a
reasonable battery. That’s going to cool a room or a camper, though, and not a
house.

~~~
criddell
Isn't the humidity in the PNW way too high for swamp coolers to work?

~~~
mikestew
High? I keep an accurate and calibrated hygrometer in the musical instrument
room, and it's the rare day when it goes over 50% in Redmond. That said, I've
never used one in the PNW.

According to the chart at the bottom of this article, it's not optimal, but
it'll take the edge off: [https://www.air-n-water.com/common-swamp-
mistakes.htm](https://www.air-n-water.com/common-swamp-mistakes.htm). And for
most summers, this one being an exception, our problems with heat are in the
high desert east of the mountains.

------
finnn
This reminds me of a power box I built for Burning Man this year. The I had
~700W of solar panels, and in a box I put an MPPT charge controller, rather
than the PWM charge controllers shown here, I had a 1kW inverter rather than
150W one shown here, but also tried to make most people in my camp use DC when
possible, offering 2 USB plugs for each person in the camp, radio charging
with a DC-to-DC converter, and a fuse box to prevent accidents. It worked out
quite well, and we successfully ran a chest freezer and a number of other
things off solar in the middle of the desert for a week.

Also, I used 2x100Ah deep cycle marine batteries + 2 additional batteries of
unknown capacity, probably between 50 and 100Ah

~~~
stevenwoo
Does battery type matter for the charge controller? Just learning about the
differences between deep discharge lead acid versus lithium in another thread
- can the charge controller optimize for battery life of either type?

~~~
okreallywtf
In short, yes. In my experience MPPT and PWM generally are used in similar
situations, the difference mainly being in how they charge and MPPT "making
the most" of the available power (which is why they tend to be more expensive)
and charge the same types of batteries.

Both charge batteries using pulses rather than a constant voltage which
extends the lifetime of the batteries compared to a cheap automotive charger
that would over time reduce the capacity of the battery), all of which is
geared towards lead acid.

Most PWM or MPPT charge controllers I've seen only support lead acid (which
come in a variety of configurations, some vented some not) and do not do li-
ion, at least not out of the box. Theoretically they have the hardware to do
it (my CC can do 12v, 24v, and 48v systems) but maybe not the software.

Lead acid batteries have been probably the most commonly used in renewable
energy projects for a while due to their cost-density but li-ion seems like a
superior choice if you can front the initial cost. I've been looking at them
but also feeling like in 5-10 years there might be more alternatives so
replacing lead acid batteries every 5-10 years seems better for me at this
point.

------
crwalker
Refreshingly practical site.

This is exactly why I think solar will beat nuclear hands-down. Solar enables
gradual adoption, unlike nuclear's power-plant sized step function. Regardless
of the actual price in $/kWh, people like doing easy things.

~~~
VectorLock
If you're going to be grid free you're going to need some kind of power
storage.

So unless you can build a flywheel for $100 you're kind of stuck with
batteries.

~~~
Iv
What is the problem with batteries?

------
jerich
This article and its predecessor made me think about smaller-scale solar, and
I actually bought a 100W panel out of the Amazon gold box last week to start
playing around myself.

My first plan is to use the panel and battery to run a set of 12V led outdoor
lights, but I'm also thinking about trying to tie into the existing 12V system
that I never bother turning on.

That's got me thinking about taking it a step further and adding some capacity
to power my Christmas lights this year. Now that they're LEDs as well, it
seems it should be possible, but probably not cost effective.

I keep thinking there must be a decent market in between tiny panels powering
path lights and a full rooftop system. Like a standalone patio cover or
pergola that has solar panels for a roof. That should give a decent amount of
power, and it could be an easier sell to people instead of permanently
attaching something to their roof.

Actually, I was trying to think of a way to run a small air conditioner from
solar—like one of those split systems. The AC could run when the sun is out,
which is when the upstairs of my house gets hot. It would be a supplement to
my central AC, so I wouldn't be worried about it not running at night or
cloudy days. So, I don't need a lot of storage or even worry about tying into
the grid.

Again, though, it's probably not cost effective piecing it together, but still
the solar patio cover seems like something that should available in a big box
at Home Depot or Costco these days.

~~~
nikodunk
Wow, this is a great point – put a lot into perspective for me. This is
exactly where I think there may be a gap in the market too – between path
lights and rooftop solar. How to make a business around it without it being
straight commoditized to Costco or Home Depot, though? Not that ending there
would be a bad thing, but it makes it less of a viable business to build in
the US...

------
ChuckMcM
Some additional data (and comments) From the previous post about the system:
[https://news.ycombinator.com/item?id=14821478](https://news.ycombinator.com/item?id=14821478)
here.

------
donquichotte
The kit consists of a 100W Pmax solar panel and a 420Wh [edited: this falsley
said 420Ah before] deep cycle lead acid battery. The battery is pretty heavy
and in the picture the setup is mounted on a car.

Let's keep in mind that a car alternator has 0.5-2kW and you need to burn
<0.1l of gas to charge that battery once with the alternator. I'm not sure its
worth all the extra equipment and cost to go full solar.

Edit: The solar panel probably gets you 360Wh to 900Wh per day, depending on
how sunny the region you live in is. This is not enough to run a household
refrigerator, but enough to charge your phones or laptops and some lights.

~~~
arbitrage
Optimizing for cost is not always the top priority.

For example, when you're camping or at another event with lots of people
around. There's nothing quite as abominable as a fleet of autos chugging along
in a loud cacophony.

~~~
sly010
> There's nothing quite as abominable as a fleet of autos chugging along in a
> loud cacophony.

If you have been to burning man you know there are things way more abominable.

That said, I agree cost is not the priority. Convenience is.

------
burkemw3
Looks like this is a new site.

The previous 'post' focused on apartments was discussed
[https://news.ycombinator.com/item?id=14821478](https://news.ycombinator.com/item?id=14821478)

------
mamcx
I have a desire to use something like this for a mining rig with 4 nvidia 1070
cards, but have conflicted info in what need.

According to [https://www.nvidia.com/en-
us/geforce/products/10series/gefor...](https://www.nvidia.com/en-
us/geforce/products/10series/geforce-gtx-1070/), the cards pull 150w. But how
to know what setup work?

BTW: I live in Medellin, Colombia and have sun like half-day for sure.

~~~
ars
Energy is interchangeable. You don't need to attach the solar power to the
mining rig.

Just use solar power for whatever, and grid power for the mining rid and it
works out the same.

~~~
mamcx
Ok, but how calculate what I need (ie: How many solar panels, battery, etc)?

------
thinkcontext
This is described as "green" but as a portable the panel will never produce as
much energy as it took to manufacture it. Taking this deficit into account
plus the energy and other environmental harm embodied in the battery, which
will also likely be sparsely used, and its doubtful you beat diesel by much.

To truly be green you would either do without or not go.

~~~
edkennedy
I've always wondered about this logic... Seems like the greenest thing a human
could do would be to decompose underground.

~~~
mac01021
That's probably true, if you don't want to count your influence on the carbon
footprints of other people when calculating your "greenness". You should
probably count it though.

So then, the very greenest things you can do probably involve mass murder and
industrial sabotage.

Further down the list, after those, you have leading an ascetic life of
minimal consumption and minimal travel while devoting yourself to the right
sort of political advocacy.

A bit further down is dying underground as soon as possible. But it's
important to note that a small amount of advocacy, sabotage, or murder per
year can make it a net positive for you to continue living.

Way below all that stuff that nobody wants to do (and who can blame them) are
(a) living as a hermit in the woods eating only berries and mushrooms or (b)
living a normal life with a normal career and making consumer choices like
buying solar panels and electric cars when other people might buy various
combustion machines.

If you're not counting your effect on other people, (a) is a clear winner.
However, people's consumer choices do have an effect on the direction of the
economy. And, if you take those effects into account, I honestly don't know
how to decide whether (a) or (b) appears higher in the greenness ranking.

------
kawsper
Is it safe? Is the battery protected against going under or over capacity?

~~~
peterwwillis
They include a solar controller + battery regulator in the parts list.

~~~
VectorLock
I don't think the solar controller or the inverter has undervoltage
protection.

------
anderspitman
Not nearly as turnkey, but for a little extra fun you can also build your own
battery bank from reclaimed laptop batteries. Search youtube for 18650 battery
bank.

~~~
cr0sh
Actually, if you want a (relatively) cheap battery bank for solar, find a
place to sell you used golf cart batteries. They are typically 6 volt, but are
deep cycle (big and heavy). Wired up properly, they can work really well, and
cost a fraction of what new batteries would.

------
izzydata
How many months / years would it take for this to generate $200 worth of
electricity at some normal price for electricity in the US?

~~~
ars
It generates about 1kw per day. Worth say $0.15. So about 4 years, if you
never have clouds.

In the real world I'd probably double that to 8 years.

~~~
izzydata
Oh.. so I guess it wouldn't be worth it unless you are away from the grid.

~~~
ars
Keep in mind part of the cost is the battery, and you would not need that if
you are grid connected.

On the other hand the inverter would be more expensive, since you can't just
use any old cheap inverter, but you need one that is true sine wave (cheap
ones are filtered square wave), and able to phase and voltage match to the
grid.

~~~
sushid
People said this on the previous DIY solar thread, but I wasn't sure where to
exactly look for one. Could you link me to one that is a true sine wave?

And how would I verify that this works for my electricity provider (PG&E in
San Francisco)?

~~~
ars
Sorry, I don't have any product suggestions. Google for "Grid-tie inverter".

And don't forget true sine wave is not enough, it must also voltage, and even
more important, phase, match.

You don't need anything specific to any particular electricity provider.

------
Pigo
As soon as you get into batteries, aren't you still treading into non-eco
friendly waters? I suppose this is more about self-sufficiency, but you're
still relying on rare metals that come from questionable sources and are
excavated by the same old diesel power.

~~~
stevenwoo
Is the alternative no batteries at all for no power at night/overcast days or
is lead-acid OK over lithium or not?

~~~
cr0sh
Most batteries are made to be recycled. Only a fool throws rechargeable
batteries in the trash (not to mention such batteries being bad for the
environment disposed of in such a manner).

There are plenty of places to recycle both lithium-chemistry and lead-acid
batteries (plus any mercury containing hearing-aid and similar cells). For car
batteries, you can usually trade in the old battery for the "core charge",
otherwise there are places that purchase old lead acid car batteries and
similar.

Virtually everything in those batteries is recycled, and usually turned into
new batteries again (heck, I think they ever recycle the sulphuric acid, too).

------
mmjaa
.. I'm guessing I'm not the only one who would be quite happy if someone would
do a smaller, lighter, cheaper version of this:

[http://smartflowersolar.com](http://smartflowersolar.com)

Perhaps DIY is the way to go.

------
josephpmay
This would be a really great small-generator alternative for hurricane zones

~~~
GigabyteCoin
Not much sun in the middle of a hurricane.

~~~
netule
There is afterwards when you don't have power for two weeks. I sure could have
used _anything_ after Wilma in 2005 to beat the heat.

------
quickben
To save people some time:

Solar panel can push 100W in. Invertor can pull 150W out.

~~~
CalRobert
Can you elaborate? I'd love to get 150 joules out of a system I only put 100
joules in to...

~~~
quickben
Time is a factor. You have to charge for 1.5 hours to be able to pull in 1
hour (minus system losses)

------
timmaah
Why do the green straps appear to be going directly over the panel? Surely
that is not the final mount position?

~~~
nikodunk
The winds in the dust storms were mad strong – I think Sean battened it down
with the straps for safety. I still regret not getting a photo when he
initially had the panel tipped forwards towards the camera (worse for
generation, better for photos...).

------
Tepix
What if I source the parts from AliExpress instead of Amazon? Should be quite
a bit cheaper, right?

~~~
dboreham
Possibly not UL approved though.

~~~
hh2222
I'd recommend adding fuses. One between the panel and charge controller, and
one on V+ to the battery.

~~~
okreallywtf
I would say it is an absolute necessity. Charge controllers have a tendency to
fail resulting in a dead short (connecting + to - on the battery, resulting in
a fire, explosion or something in between).

I had this happen on a properly wired off-grid system (bad diode) and it would
have been quite bad had it not had a breaker of the appropriate size. I would
not sleep next to a battery that wasn't fused or breakered.

Reminder: DC systems and AC systems require differently rated components. You
cannot just go buy a 30A breaker from home depot for the DC side of your
system. It takes a lot more to disconnect DC than it does in AC (because AC
cycles to 0V 60x/s it doesn't take much of a gap/insulator to break a
connection, DC is not the same. Trying to use a light-switch for a DC light
can result in problems [1].

I've had good luck with midnite products (charge controllers and breakers,
etc) [2]

[1] [http://blog.gogreensolar.com/2015/02/ac-vs-dc-
breakers.html](http://blog.gogreensolar.com/2015/02/ac-vs-dc-breakers.html)

[2]
[http://www.midnitesolar.com/products.php?menuItem=products&p...](http://www.midnitesolar.com/products.php?menuItem=products&productCat_ID=16&productCatName=)

------
travbrack
Pretty neat, but how do you get ice to burning man for the swamp cooler?

~~~
pacificmint
Ice is one of the two things they sell at Burning Man.

(Officially. In reality there are a few more things that they sell, but the
'only two things' label has stuck).

Edit: Also, you don't need Ice for a swamp cooler. You don't even need cold
water. The water temperature doesn't really matter, as the temperature drop
comes from the evaporation, not the water temperature.

------
mrfusion
Why not use a ups for the battery?

~~~
detaro
Can't efficiently charge from solar, so you need an external charger anyways.
Not really cheaper than an inverter. Cheaper ones are not intended to run
continuously and may overheat.

~~~
jandrese
Also, most will beep annoyingly once the sun goes down.

