Small solar solution for emergency backup power in Puerto Rico

[michael glaser]

Thank you in advance - as they say - to ANYONE who can help me figure out how/whether a small solar solution could help my brother in Puerto Rico. Still no water/power. Just candles and a garden hose with "water". I have info overload from DIY sites. Can an average person set something up for under $500 and would it be enough to charge some devices and maybe a lamp? Not sure where to start..

Please spread the word, I am getting desperate!Michael

 

[anorlunda]

Sure you can help. But keep it simple. I see numerous devices on amazon.com from search terms "solar phone charger" and for "solar light". You could buy 8-10 of those devices for less than $500. No set up. No wiring. No DIY. No safety problems.

To keep it simple, think of one solar charger per device.

In the package you could also include several solar garden lights. They are available in your local hardware store, or even the dollar store. They don't make much light, but they could be placed several places in the house as night lights.

You gave me an idea. There are places near me that gather donated goods to ship to Puerto Rico. Most of it is food. But some of those solar phone chargers might be greatly appreciated.

Edit: I just found one device online, that has two USB charger ports (15000 mah) and with LED lights in the same device, for $16.99. Perhaps you should buy one for yourself first to test it. Look at your inbox for a PM.

 

[OmCheeto]

Thank you in advance - as they say - to ANYONE who can help me figure out how/whether a small solar solution could help my brother in Puerto Rico. Still no water/power. Just candles and a garden hose with "water". I have info overload from DIY sites. Can an average person set something up for under $500 and would it be enough to charge some devices and maybe a lamp? Not sure where to start..

Please spread the word, I am getting desperate!Michael

$420 is the price I came up with for such a system.
You can probably get away with something for $300 if you have no desire to expand.

cost / component / notes
$100 / solar panel / 100 watts 12 volt [example I found]
$ 20 / battery charge controller / 120 watts 12 volt [example I found]
$100 / battery / 1200 watt hour marine deep cycle lead acid [just google it]
$200 / inverter / 1000 watts pure sine wave [example I found] (for just lighting, you can get a 400 watt inverter for about $50, which is what I have)
---------
$420 / total

I've been using portable 50 watt panels for about 10 years. They're a really nice size for transporting by hand by only 1 person.
The 100 watt panels shouldn't be too much more difficult to use if they are just going to keep them at home. I hauled mine all around the state(camping and stuff).
They can be be taken down and stored during a hurricane, and set up in about 30 minutes after the wind dies down.

I recommend the larger, pure sine wave inverter, as, once you start using solar, you start figuring out that you can use it for anything.
My 400 watt inverter was barely able to start my $10, 100 watt, garage sale micro refrigerator. (Surge current)

Of course, if they want to power a refrigerator, it will cost more.
I designed a system for my friends in Florida after hurricane Irma for about $3000, as they were whining about air conditioning.

1st world problems...

ps. My friends in Florida opted just to drive a few miles to their parents house, as they had electricity there. Doesn't sound like an option in Puerto Rico.

 

[Tom.G]

For night lights, those solar garden lights that @anorlunda mentioned seem ideal. For more general lighting I recommend lights that work from whatever battery voltage you use. AC power inverters peak at around 85% or so efficency but are much worse when supplying little current. Of course LED lights where ever possible will give much more run time than incandescent or fluorescent ones.

 

[OmCheeto]

For night lights, those solar garden lights that @anorlunda mentioned seem ideal. For more general lighting I recommend lights that work from whatever battery voltage you use. AC power inverters peak at around 85% or so efficency but are much worse when supplying little current. Of course LED lights where ever possible will give much more run time than incandescent or fluorescent ones.

I'm currently in the middle of a test of my system. (battery, inverter, LED lamp) I plugged in a 4.2 watt LED lamp 13.5 hours ago. Battery voltage is down to 12.2, indicating battery capacity is down to about 50%. Which is way too far down, as 4.2 watts * 13.5 hours = 56.7 watt hours, which is not even close to 1200 watt hours. Though battery voltage as an indicator of state of charge while under load is not very reliable. I'll continue the test until voltage reaches 12 volts. The battery is 3 years old and I've used it probably only a couple of times. It may be suffering from stratification.

Uh oh. Looking at my comments above, I might be adding fuel to the "information overload" fire.

@michael glaser , batteries are like people.

1. If you make them run the 100 yard dash, they lose capacity faster than if you make them run a marathon.
2. They get gas if you feed them incorrectly.
3. They get tired when they get old.
4. Batteries that don't get regular exercise get lazy.
5. You can kill or harm them if they become dehydrated.
6. Hydrating them with anything other than distilled water will kill them.
7. Lead acid batteries are like Omcheeto: OVERWEIGHT!​

The maths involved in "basic" battery theory are pretty simple though:

volts (12.75) x rated amp hours (100 in my case) = 1275 watt hours ... (<---- battery capacity)

volts x amp hours = watt hours​

1275 watt hours(my battery) ÷ 4.2 watts(my lamp) = 303 hours ... ( <---- how long your battery will/should last)

watt hours ÷ watts = hours
​

Of course, Tom.G is correct about inefficiencies of inverters. One moment.
...
...
Wow! My inverter is drawing 8.9 watts and only delivering 4.2 watts.
It's only 50% efficient at super low load.

Tom.G is correct. It is more energy wise to use 12 volt light bulbs.
Though I would recommend a $50, 400 watt inverter, for odd things, like my laptop, which did not come with a 12 volt DC charger.
But that's just me. I would DIE without the internet. (another 1st world problem )

 

[sophiecentaur]

7. Lead acid batteries are like Omcheeto: OVERWEIGHT!

How often would that be a problem? Lead acid is still the best value in many respects and you can replace them from a local Garage in an emergency.

Tom.G is correct. It is more energy wise to use 12 volt light bulbs.

Absolutely. Avoid going to mains voltages for most of your wiring. Where necessary, use a mains inverter for feeding equipment that has to be mains voltage but less and less stuff is only available in Mains Electric. Low power = 12V High Power = Petrol Engines.
Use good quality LED lights and you save by using smaller panels and batteries. (Cheap LEDs could let you down but I think 12V Less would be better behaved than mains voltage LEDs.

 

[OmCheeto]

It would appear that my local situation has skewed my knowledge of solar power potential.

Having pretty much negligible solar available, I've not invested in current technologies.
I've always just hooked my solar panels directly to my battery.
My experiment yesterday indicates that I might have been ignoring PWM & MPPT technologies:
My 95 watts worth of solar panels were only delivering 66 watts of power to charge my battery.

The following video indicates that I would be happiest with MPPT technology:



A snip from the middle looks like the PWM device is about the same as no device as all:

Googling indicates MPPT devices are not that expensive:

40A MPPT Solar Charge Controller [example I found]
$150​

Although that would increase* the cost of my system by $130, I think it would be worth it. (About the cost of a 100 watt solar panel)

ps. From the video; "Caveat emptor" as to what MPPT device you buy.

----------------------
*dollar store charge controller I found previously: $ 20 / battery charge controller / 120 watts 12 volt

 

[sophiecentaur]

It would appear that my local situation has skewed my knowledge of solar power potential.

View attachment 213764

Having pretty much negligible solar available, I've not invested in current technologies.
I've always just hooked my solar panels directly to my battery.
My experiment yesterday indicates that I might have been ignoring PWM & MPPT technologies:
My 95 watts worth of solar panels were only delivering 66 watts of power to charge my battery.

The following video indicates that I would be happiest with MPPT technology:



A snip from the middle looks like the PWM device is about the same as no device as all:

View attachment 213767

Googling indicates MPPT devices are not that expensive:

40A MPPT Solar Charge Controller [example I found]
$150​

Although that would increase* the cost of my system by $130, I think it would be worth it. (About the cost of a 100 watt solar panel)

ps. From the video; "Caveat emptor" as to what MPPT device you buy.

----------------------
*dollar store charge controller I found previously: $ 20 / battery charge controller / 120 watts 12 volt

IMO you should investing a chain saw and reveal the Sun for a bigger part of the day.

It's always interesting to discuss a real implementation such as yours.
Your 66W from nominal 95W panel is no surprise to me. From what you can read, it appears that there is a significant amount of energy to be had when the volts from the PVs are not optimal so the MPPT regulator could be good value. My very cheap and cheerful regulator (based on a 40W panel) has a Boost Mode when the PV volts are low. It seems to spend most of its time in that mode but the actual charge current is pretty pathetic, of course. I have ruined one battery by draining it too much and too often. I think it will need several times the present capacity to avoid that problem. The actual nominal capacity that's needed to achieve a given usable capacity is one thing that could make it worth while going from Lead Acid to something more modern.
MPPT devices have very varied performance and I think you may be stuck with paying the high price of one from a 'specialist' Solar Energy firm, rather than a cheap one from China. There is a rich vain of opinions and experience on Sailing and Boating (and camping) Forums and I would recommend a bit of browsing in that direction.

 

[OmCheeto]

IMO you should investing a chain saw and reveal the Sun for a bigger part of the day.
Also, a spot of Glyphosphate could damage trees that are not on your property. Done surreptitiously, it could look like a weird disease and not sabotage.

Most are over 100 feet tall, so chain sawing and killing them are not options. (For me anyways. And they ALL belong to my neighbors.)

It's always interesting to discuss a real implementation such as yours.
Your 66W from nominal 95W panel is no surprise to me. From what you can read, it appears that there is a significant amount of energy to be had when the volts from the PVs are not optimal so the MPPT regulator could be good value. My very cheap and cheerful regulator (based on a 40W panel) has a Boost Mode when the PV volts are low. It seems to spend most of its time in that mode but the actual charge current is pretty pathetic, of course. I have ruined one battery by draining it too much and too often.

My last battery died (2014) because I ignored the fact that it sat an entire winter uncharged.

I think it will need several times the present capacity to avoid that problem. The actual nominal capacity that's needed to achieve a given usable capacity is one thing that could make it worth while going from Lead Acid to something more modern.
MPPT devices have very varied performance and I think you may be stuck with paying the high price of one from a 'specialist' Solar Energy firm, rather than a cheap one from China. There is a rich vain of opinions and experience on Sailing and Boating (and camping) Forums and I would recommend a bit of browsing in that direction.

It's academic now as to which MPPT device I should have bought, as I have one on order now. It is scheduled to arrive on Monday. $120, 20 amps, 12 or 24 vdc, Deep cycle Sealed, Gel, Flooded and Lithium battery option ready.
I ordered it from a local mega-home improvement store, as I assume they don't sell knock-off junk.

Anyways, my criteria ideas for Puerto Rico are:

1. Fast setup

• I didn't document my setup time, as chasing the sun around my neighborhood required me to manufacture extra extension cords. Breakdown time was very fast: <30 minutes. So right now, I could drag my solar panels out to my driveway, and have AC power in about 10 minutes. Actually, the battery is in my living room with everything but the panels hooked up, so I could turn on my lights right now. I've heard that Puerto Rico's grid wasn't that reliable before the hurricane, so many of the residents may want semi-permanent installations. Perhaps a grid powered float charger would be a good post-disaster add-on option.
• Tesla actually did this for a children's hospital. They simply put their panels in a parking lot, ground level, kind of like I propped up my panels in my driveway.

2. Simple setup

Aside from the charge controller, I can't imagine anything simpler to set up.​

3. Non-obsolescence once grid power comes back on

As I've mentioned before, I've had my panels for over 10 years now, and use then only for experiments. I think they will last 100 years at this rate.
The battery is the only thing I'm worried about amateurs ruining, but even us experts can do that.​

4. Cheap as possible, but not junk

Difficult, but not impossible, given that we have google, and PF!​

5. Minimal but somewhat expandable

If I had as much available solar potential as they do, I'd invest an extra $100 to double my capacity.​

6. The "Look at that!" syndrome.

Setting up a single, 100 watt system in each town, might get people interested in why only one person in town has lights at night, and coffee in the morning.​

​