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hyaku

Another going solar thread

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hyaku

Well I am taking the plunge. After two big typhoons and more than a few brownouts I ordered two large panels, batteries etc etc. I will put them on raised adjustable frames in the garden, News of a storm and I can quickly disconnect and bring inside. I plan to power the ref and a few lights. Biggest problem we had after storms was no way of preserving food. I will lay a small water pipe to hold the cables into the house. The ref is 176 watt and will be permanently off grid. Hopefully a few more appliances will be plugged in.

 

Any advice anyone?

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Oz Jon
The ref is 176 watt and will be permanently off grid. Hopefully a few more appliances will be plugged in. Any advice anyone?

 

Is that a (12 volt?) battery operated fridge?

 

What are the voltage and current ratings on your panels?

 

If it has a motor, there can be a very heavy starting current demand (up to 5 to 8 times normal) for a few seconds. Have you looked into that?

 

Cheers, Oz Jon

Edited by Oz Jon

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woodchopper

hmm,,seems like this problem of storing the power can be difficult,,not the least,,expensive!

 

going back "into the grid" seems ok for some but 1 fellow near my past home installed a very large wind turbine,,its now gone also!

 

is it true that solar panels run just as efficient in non direct sunlight?

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Oz Jon
Any advice anyone?

 

What advice are you looking for?

 

a)

The first thing you need to know for your fridge exercise is how much energy does the fridge consume per day.

That's it's wattage (176W?) times the number of hours it is running per day.  The load answer will be in watt.hours.

 

Typically fridges run for about 30% of the time = 8hrs/day so that would be about 8x176=1408 watt.hrs required.

(that's in Aus, probably longer in the temperature and humidity of the Phils and depending on it's energy star rating and how frequently you open it's door and let a lot of cold air out and warm air in!) .

 

b)

Next, you need to match that energy demand with the solar supply.

The maximum supply will be the panel's nominal wattage times the number of hours per day it gets good sunshine.

Again the supply answer will be in watt.hours.

I don't have typical daily sunshine hours for the Philippines, but my guess would be about 6 hours per day (averaged over the whole year).

So I guess that a 100watt panel would produce a maximum of 600watt.hours of energy per day. ( So you need at least 200Watts of panels)

 

c)

.... note that I said maximum!!!!  .... the system including batteries and solar regulators (maybe also inverters) is far from 100% efficient, so you will need more generating capability...... maybe twice as much needed? ... more information needed to get an accurate number.

 

Have I managed to confuse you yet? - Lol!

 

Get back to me if you would like more! - Lol!

 

Cheers Oz Jon

 

 

OOPS! - fixed my faulty arithmetic!

Edited by Oz Jon
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BlueFin

As you're learning about your needs and requirements, a Power Meter will come in handy.

 

I bought one of these just last week: http://uplift.ph/Accessories/Products/Digital-Power-Reader

 

P1,554 including online purchase and delivery.

 

It does handy things like tell you Watts used (min and max), Amps, Usage over time etc.

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Oz Jon

hmm,,seems like this problem of storing the power can be difficult,,not the least,,expensive!

 

...................................................................................................................................................................................................

 

 

 

You've got it right - the killer with all solar concepts is energy storage! - storage is expensive and can be troublesome.
 
Solar panels are less efficient in indirect light, but they do produce some power.
Edited by Paul

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Oz Jon

dont tell them that mate,,most ofem are yanks,,,,,,,,, :killself:

 

but seriously,,this solar stuff is interesting in how and what to do,,i just wanna charge cellfones and laptops?

Charging low power stuff like cellphones and laptops is easy - don't even need battery storage if you do it during the day when there is at least a bit of sunshine.

 

The problems start when you need power at times when there is no sunshine. And even bigger problems when you want to start/run motors.

That needs batteries and they are expensive and troublesome.

Edited by Oz Jon

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hyaku

What advice are you looking for?

 

a)

The first thing you need to know for your fridge exercise is how much energy does the fridge consume per day.

That's it's wattage (176W?) times the number of hours it is running per day.  The load answer will be in watt.hours.

 

Typically fridges run for about 30% of the time = 8hrs/day so that would be about 8x176=1408 watt.hrs required.

(that's in Aus, probably longer in the temperature and humidity of the Phils and depending on it's energy star rating and how frequently you open it's door and let a lot of cold air out and warm air in!) .

 

b)

Next, you need to match that energy demand with the solar supply.

The maximum supply will be the panel's nominal wattage times the number of hours per day it gets good sunshine.

Again the supply answer will be in watt.hours.

I don't have typical daily sunshine hours for the Philippines, but my guess would be about 6 hours per day (averaged over the whole year).

So I guess that a 100watt panel would produce a maximum of 600watt.hours of energy per day. ( So you need at least 200Watts of panels)

 

c)

.... note that I said maximum!!!!  .... the system including batteries and solar regulators (maybe also inverters) is far from 100% efficient, so you will need more generating capability...... maybe twice as much needed? ... more information needed to get an accurate number.

 

Have I managed to confuse you yet? - Lol!

 

Get back to me if you would like more! - Lol!

 

Cheers Oz Jon

 

 

OOPS! - fixed my faulty arithmetic!

Thanks Jon

 

The plan was 2 deep cycle solar batteries

Nominal Voltage: 12V

Capacity (25°C):

10HR (13.6A) - 136.0Ah

5HR (24A) - 120Ah

1HR (88.3A) - 88.3Ah

 

2x100 watt panels

 

A 1000 watt inverter

 

The ref: Is a Panasonic inverter 50Hz Total consumption over 24 hours is 0,763KwH

 

I am sure this will be a bit more expensive but the brownouts alone are a pain in the butt going off for 12 hour stints.

Edited by hyaku
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Paul
Any advice anyone?

 

12v or 24v system? 

 

 

EDIT: I saw the answer to this question later in the thread.

Edited by Paul

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Paul

Thanks Jon

 

The plan was 2 deep cycle solar batteries

Nominal Voltage: 12V

Capacity (25°C):

10HR (13.6A) - 136.0Ah

5HR (24A) - 120Ah

1HR (88.3A) - 88.3Ah

 

2x100 watt panels

 

A 1000 watt inverter

 

The ref: Is a Panasonic inverter 50Hz Total consumption over 24 hours is 0,763KwH

 

I think we can safely say, this will NOT power a refrigerator 24 hours per day, 7 days per week. 

 

I am in the middle of something, but will calculate this out and reply within an hour. 

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Oz Jon

Thanks Jon

 

The plan was 2 deep cycle solar batteries

Nominal Voltage: 12V

Capacity (25°C):

10HR (13.6A) - 136.0Ah

5HR (24A) - 120Ah

1HR (88.3A) - 88.3Ah

 

2x100 watt panels

 

A 1000 watt inverter

 

The ref: Is a Panasonic inverter 50Hz Total consumption over 24 hours is 0,763KwH

 

You were asking for advice - seems like you already knew a fair bit about the topic or had some good advice already! - Lol!

 

 

That's a serious pair of batteries!

I was concerned about motor starting current - but they can deliver that OK!

 

I am very surprised at the low energy needs of the fridge though - only about half what I expected - on for only a bit over 4hrs/day!.

Is that a manufacturers claim or an actual "real-life-in-the-Phils" measurement?

 

You didn't list one, but I presume that you have a "smart" solar controller too (a maximum power type with a low voltage battery disconnect* capability)?

 

Looks like you're set to go!

 

Let us know how it works out after the first month.

 

Cheers, Oz Jon

 

* to protect your batteries from too much discharge - VERY important!

Edited by Oz Jon

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woodchopper

Charging low power stuff like cellphones and laptops is easy - don't even need battery storage if you do it during the day when there is at least a bit of sunshine.

 

The problems start when you need power at times when there is no sunshine. And even bigger problems when you want to start/run motors.

That needs batteries and they are expensive and troublesome.

 

ok,,tx mate,,i might buy a small cdr panel and try!

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hyaku

Jon, yes a controller as well. The ref is hardly ever on, ridiculously quiet, Seems to operate on a lower level compressor when fully cold. We have it on the lowest setting but the upper level still freezes if things are in there too long. My bill is down P300 since we gave away the old one. In all I consume around 150KWH a month with all appliances. 

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Paul

Any advice anyone?

 

Firstly, your most effective way to do this would be NOT to take ANYTHING 100% off grid. On grid power is going to be cheaper than off-grid power.

 

Secondly, take a look at this thread, where I posted about a guy's "Automatic Transfer Switch" idea from 2008. I am waiting for two relays and base mounts now, to make up this same switch. It was designed specifically for running a refrigerator when the mains power fails. 

 

Thirdly, the calculation you need to go by to determine your array size for off-grid charging of 272 amp hours worth of battery, roughly, is this: 272AH X 14.5 volts charging / .77 array efficiency X .10 (rate of charge) = 512 watts array

 

So, if you go with the transfer switch idea, you can go with a smaller array, and a smaller bank of batteries. The difference is, you will be running off the mains UNTIL the mains fail. Then, your refrigerator will switch over to the inverter and batteries, automatically. 

 

If you have a good quality inverter, it will go into "sleep" mode until it detects a draw in power. Once it does, it will "switch on" and provide the necessary power for the refrigerator. 

 

Keep in mind that, when you discharge batteries below 50%, you start seriously affecting their longevity. 

If you can get hold of some golf cart batteries, they would work very well for these applications. 

 

Any questions?

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Paul

Oh, the bare minimum array I would run, to keep that bank charged, would be about 300 watts. 

 

You need to keep in mind days of autonomy (if the mains are down and if there is a storm for x number of days).

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