Solar Power Info for small off grid system

Chinwi · 21 Re: Solar Power Info for small off grid system Tue Mar 26, 2013 3:22 pm

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@Lokka1 wrote:Considering the economics, what I can recommend is to switch to a refrigerator as they use in small boats using 12v or 24v DC and use the solar powered system recommend by Chiniwi. You might be able to even get your existing refrigerator converted to use DC electricity if there are no sophisticated electronics.

Wow !

This opens a new avenue for an innovative investor / businessman.

Many years ago I assembled a miniature A/C / Fridge like gadget with the help of refrigerator guy to use in a orchid growing chamber where you need low temperature.

[When you propagate orchids by seeds or mericloning you have to keep them below 25C for many weeks/months continuously. Running an A/C from start to end of this period makes the cost of plants very high.
Hence we tried to give a Solar power solution .]

We used car A/C compressor run by 12 V motor pulley.
Due to high cost of Solar panels we could not make it that good and viable.
I think 40-60W panel was over 60,000/- those days.

Thank you Lokka1 for reminding this again !

12 - 24 V mini refrigerators could become a popular household item in future . 40W = 7,000 is very interesting.

OnlyGuru · 22 Re: Solar Power Info for small off grid system Tue Mar 26, 2013 6:19 pm

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GMNet

Who was the supplier, is Rs 750,000/- all inclusive (net metering, Solar panels, installation & commissioning)?

rmark · 23 Re: Solar Power Info for small off grid system Tue Mar 26, 2013 7:04 pm

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There are number of companies supply net metering system in Sri Lanka. I got some information on net metering system/suppliers during the Architectural Exhibition @ BMICH held in last month.

smallville · 24 Re: Solar Power Info for small off grid system Tue Mar 26, 2013 7:11 pm

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@OnlyGuru wrote:GMNet

Who was the supplier, is Rs 750,000/- all inclusive (net metering, Solar panels, installation & commissioning)?

CEB has introduced a plan to reduce ur bills by Net Metering Solar Power system for Homes..

http://www.solarenergysrilanka.blogspot.co.uk/2012/06/net-metering-investment-in-solar-energy.html

OnlyGuru · 25 Re: Solar Power Info for small off grid system Tue Mar 26, 2013 7:48 pm

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Thanks smallville,

I have seen this site and received a quotation from JLANKA for a friend of mine, which they quoted was Rs 980,000/-and for festive its Rs 675,000/- will generate around 170 units a month.

But GMNet mentioned he has one which will generate 15 units a day which means (15 X 30) = 450 units for Rs 750,000/- That's why I wanted to know from where did GMNet get this cheap.

Anyways thanks alot.

Jeremy · 26 Re: Solar Power Info for small off grid system Wed Mar 27, 2013 2:34 pm

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Solar Power Info for small off grid system - Page 2 Solspe10

Solar Power Info for small off grid system - Page 2 Solspe11

Expert · 27 Re: Solar Power Info for small off grid system Wed Mar 27, 2013 3:49 pm

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Wow!
I have missed a lot....

This is very interesting and useful. I didn't know that the solar panels have come down so much in price. I recently saw a panel at the shanty near the sea at the Bambalapitiya railway station and wondered how they could afford it; I thought it must have been a donation and yes, it could very well be.

A laptop runs on a battery and I believe it is 12V; I just checked from a friend and he says there are 15V and 19V chargers for laptops :-( . And a UPS also keeps its charge in a sealed lead-acid battery and that too I think is 12V and since it generates back 230V AC current, it must have an inverter built in: some food for thought. But remember that their capacity is low and they may not be able to power anything big.

Yes, I am fully in support of a battery operated refrigerator. Recently I saw in a car advertisement that there is some vehicle for sale with a 12 or 24V small fridge. Why not use one at home?

What if the laptop battery is charged from solar power and then used in the laptop?

Now, can somebody tell me whether these panels are cost effective considering their lifetime, please?

Chinwi · 28 Re: Solar Power Info for small off grid system Wed Mar 27, 2013 7:46 pm

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@ Expert,

I like the way you think ! Smile

You can do experiments and develop a system for your need.
I do not like to publish every possible circuitry due to safety reasons.

UPS has all the gadgets inside , 230 to 12 step down, AC - DC, charger control, sealed battery, again 12 to 230 V DC to AC generator etc. I think you can remove 230 to 12 Step down part and connect 12V from Solar to battery if you can make charger control to work to save the battery from over charging. Then keep 12V to 230V part to generate enough power for laptop.

[No one should try this if you have no enough experience in doing these things. For eg. In PC power supply unit they increase the voltage to much higher than 230v before regulating it down to 12V and 5V levels. Some capacitors inside of these gadgets store over 300V even after the power is switched off ]

You should never connect 12 V DC from the battery directly to 12 V inlet of a laptop. You need small circuit to make the DC to suitable for the laptop ( balancing voltages, amperage and other factors) DC to DC converters are used for this. Car charger is OK.

Somehow, it is better to use the original charger given for the laptop and supply AC to it. ( even with some power loss)

In addition, UPS batteries are sealed lead acid thus could be a solution for low ventilation places.
As their capacity is low you can increase it by connecting them in parallel.

I think for smaller unit with 10-20 W panel 2-3 UPS batteries connected in parallel are cost effective than car batteries.

smallville · 29 Re: Solar Power Info for small off grid system Thu Mar 28, 2013 7:24 am

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A normal 600VA UPS wont power a CPU for more than 15 mins. Further, u can buy a 1.5KVA UPS (over 10000/- I think) and expect it to hold at least 30-45 mins. In addition, a UPS could also be used to power few LED or CFL lights for hours Wink

My thinking is; a car battery can be connected to a UPS removing its standard small battery to increase the power up time. So instead of 15 mins for a standard 600VA UPS, it can at least hold for more than an hour if a PC is used.

But what I'm not sure about is whether the internal circuit parts, resistors, caps, transistor, etc.. can last with the heating it can possibly emit working for such long. In that case 1.5KVA UPS at least would last couple of hrs but the 600VA one we generally use will not.
This factor has to be taken into consideration if we want to implement this solution.

@hirankb wrote:
6. Most inverters give square wave 240v AC. THIS IS VERY BAD FOR SOPHISTICATED ELECTRONICS DRIVEN DIRECTLY from inverter. Lap tops OK because of the barrier in PSU. but LeD TV's , descktops will suffer sooner than later if a low grade inverter is used. Ask for a " true Sinusoidal wave" inverter.

This point of hirankb is really valuable to look at. Many years back when the power cuts were applied Island-wide by CEB, I cooked one of my Fans powered by an inverter. At that time I didnt know abt these waves Wink

So if a UPS can be used with a car battery, it would be a good alternative to an inverter as a commercially available UPS comes with the Sine wave which is good for any electrical appliance.

Hope someone with knowledge is Electronics could clarify these things.

zenobia · 30 Re: Solar Power Info for small off grid system Thu Mar 28, 2013 9:22 am

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dear all
any brands of inverters with true sine wave AC output? (other than UPSs)
thanks
zenobia

lokka1 · 31 Sinewave Inverters Thu Mar 28, 2013 9:49 am

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@zenobia wrote:dear all
any brands of inverters with true sine wave AC output? (other than UPSs)
thanks
zenobia

I use a TRIPPLITE inverter. This is a USA made one and I can recommend it. Go to their web site www.tripplite.com which will give you additional information.
Lokka1

zenobia · 32 Re: Solar Power Info for small off grid system Thu Mar 28, 2013 10:01 am

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thanks lokka1 and everyone who gave valuable information in this thread
zenobia

jonny · 33 Re: Solar Power Info for small off grid system Thu Mar 28, 2013 10:44 am

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Dear chinwin,

Thanks a lot for your info.This is timely reqierd advice which worth alot. I appriciate if you could advice how to set up the system as welll. Like how to do the fixing.

thanks again...

Chinwi · 34 Re: Solar Power Info for small off grid system Thu Mar 28, 2013 11:14 am

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@ smallville,

A Frenchman working with us in a development project did this king of thing in 1989, IBM PC-AT DOS era ! We wanted to increase the capacity of UPS and he connected two car batteries to the UPS , externally, worked well. It was a high VA UPS.

If any problem arise it will be when charging with mains current. I have no idea about charging a battery with a bigger amperage using the charger for smaller battery of the UPS. Not tried.

When charged with solar this should not be a problem. You cannot just give the power to the battery terminals. We should know how to connect the source to the overcharging controller to protect the battery.I have not tried this. I should do some experiments.

--
About the Inverter : I have a small Belking inverter.
It is available in shopping malls in some other countries. Price : 68 US$.
I use it in an emergency only.
http://www.belkin.com/us/F5C400-300W-Belkin/p/P-F5C400-300W

@ jonny,

I will try to give a sketch.

Expert · 35 Re: Solar Power Info for small off grid system Fri Mar 29, 2013 10:16 pm

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Everything seems to be great. Does anyone know what the output of a solar panel is? Voltage and the Type of Current? DC, AC, Sine-wave, Square-wave, etc.

And what is the difference in life-time between a normal lead-acid battery used in vehicles and a sealed lead-acid battery?

And for your info: My laptop charger gives out 20V, 65W. As it is said above, as a short-cut and as a fast way to implement, we may have to step up to 230V from 12V or whatever it is and again step down to 12V or 20V or whatever the voltage our equipment work on. May be someone with electronics knowledge can consider building (and patenting) a power supply unit for a PC that takes in 12V DC from a car battery.

I checked the SolSpectrum web-site quoted above and their prices seem to be about double from what is given above: Rs.7000/- for 40W panel. Could that be a price inclusive of everything? Or are they expensive?

By the way, I completely forgot: Thank you Chinwi and all those who have and are contributing here on this thread as this is a kind of public service and a lot of people would benefit from this knowledge, if they actually use it.

Expert · 36 Re: Solar Power Info for small off grid system Fri Mar 29, 2013 10:21 pm

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Sorry it is not SolSpectrum site but the price list given in the first post in this thread.

Chinwi · 37 Re: Solar Power Info for small off grid system Sat Mar 30, 2013 9:04 am

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@Expert wrote: Does anyone know what the output of a solar panel is? Voltage and the Type of Current? DC, AC, Sine-wave, Square-wave, etc.

Output from a Solar panel is always DC. The amount of current varies with the sun light. Modern panels has high power factor. Even with a cloud cover they generate enough power to light few LED bulbs inside during daytime.

Sealed batteries have shorter life than normal batteries.

Important :
Note1:
Although we mentioned about sealed batteries with UPS chargers I have not tested them with the charger controllers designed for flooded type batteries ( car bat) .
Sealed batteries are highly vulnerable to damage when over charged ; solar chargers may overcharge them.

Note2:
Actually there are high capacity lead acid batteries designed specially for Solar storage. We did not talk about them due to price factor.

Note 3:
With mains current ( 230 V with low Amperage ) we can use thinner wires from the box to bulb. -like 1/.044 or 14/.076- because resistance generated is minimum for the little current.

When we deal with 12V, higher current is transmitted along the wires. Hence we have to use thicker wires. Car wiring cables are OK from the box to the bulbs.
From the Solar Panel to the box we have to use much thicker wire to eliminate power loss.

hirankb · 38 Re: Solar Power Info for small off grid system Sat Mar 30, 2013 9:21 am

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Let me contribute my two cents again.

Solar pannels do not give out current , but only generates a voltage , hence the name PV ( photo voltic) panels. current depend on the load.

make sure pannels are installed in a place where you have access for periodic washing. dust on the panels will obviuosly diminish the efficiency. Install a water tap to a convinient location as part of panel instalation. If not washing the panels becomes a tedious job , you probably will neglect it, specially if you have passed 40 like me.

Expert · 39 Re: Solar Power Info for small off grid system Thu Apr 18, 2013 4:27 pm

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But what is the maximum current they can generate?

Do they normally have a Voltage rating like 12V, 15V, 24V, etc.?

If there is no current specified, why the panels as said to be a certain number of Watts, like 40W?

Chinwi · 40 Re: Solar Power Info for small off grid system Thu Apr 18, 2013 6:52 pm

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@Expert wrote:But what is the maximum current they can generate?

Do they normally have a Voltage rating like 12V, 15V, 24V, etc.?

If there is no current specified, why the panels as said to be a certain number of Watts, like 40W?

Actually solar panels generate a potential difference of about 16 Volts. ( some panels give 23-26 V)

All the data is printed in the back panel.

If the Voltage given is 16 V ( normally printed as Vmp = 16V)
and if tha Wattage given is 40 ( 40W)

applying to formula W = VA

A = W / V

A = 40 / 16

= 2.5 A

It can give to a current of 2.5 Amperes when the Sun is at full bright.

--
1 Power Unit (we pay to CEB ) is 1000 watt hours

If 40 W panel is at full Sun for 10 hrs it can generate 400Whrs ( 0.4 units) theoretically.
To generate 1 Unit ,40W panel should be in full Sun for 25 hrs.

Expert · 41 Re: Solar Power Info for small off grid system Tue Apr 23, 2013 3:04 pm

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Thanks a lot Chinwi.

You are quite clear and I can understand how the calculation goes. So, does this Wattage remain the same even when the Voltage is stepped-up to 230V? I mean when the Voltage is stepped-up, Wattage remains the same but Amperage goes down?

Today I received an advertisement in the SPAM mail on a Solar PV System with an initial cost of Rs.275,000/= and a monthly payment of Rs.25,000 for 12-months. They say that the costs of Net Meter installation and special structures to mount panels are excluded. I am not sure whether the Inverter is included - that is quite expensive as I saw in their web-site. I think it is not appropriate to publish their details here but if anyone wants, I may be able to email it privately. On the other hand, many of you too would have received that mail.

Light of Hope · 42 Re: Solar Power Info for small off grid system Thu May 02, 2013 1:24 pm

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does anybody know a place to buy deep cycle batteries here

Expert · 43 Re: Solar Power Info for small off grid system Thu Jan 09, 2014 8:35 pm

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Hi All,

Thanks a lot for all your inputs in this thread and elsewhere on Solar Energy harnessing. I started with a small Solar Lantern bought for around Rs.4000/=. Now my home is powered by Solar Electricity. We used to use about 4.5kWh per day and now use 8kWh per day as we switched to electric cooking from LP Gas; so almost zero LPG bill and zero Electricity bill from Rs.3,500/= to 4,000/=. Last month, this Solar PV System produced about 250kWh and the usage was 240kWh; yet to receive the bill (of Rs.30/- being the fixed charge for zero usage) as it comes in the post. The system installed was 2kWp - eight 250Wp panels, with a 3.5kW inverter. I have plans to add the balance panels part by part until it comes to the full capacity of 3.5kW, based on other things that I would add to the circuit. I have plans to use a Water Pump to supply water to home at least for washing, to supplement the NWSDB supply and get the Water Bill also down. I had ideas to switch to a plug-in hybrid car but as my car usage is minimal right now, it can wait - I believe my car is one of the most fuel efficient sedans these days - it clocked a maximum of 25.9km/l with an average 19.4km/l (full tank to full tank) over a distance of 520km trip of four days. But, I consider buying an electric or hybrid motorbike for short distance travelling - especially to take my son for classes.

Hope this information is of use to you guys.

Best Regards.

Chinwi · 44 Re: Solar Power Info for small off grid system Thu Jan 09, 2014 10:52 pm

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Thanks Expert.

Wow ! 26km/l

I also wanted to buy a solar water pump and a vendor near Pannipitiya asked me 350,000.00 for a small domestic pump .
The price too high , not worth wasting that much of money for it.

Hence, I am trying to find a 12V motor and couple it to an impeller section of a pump.
If anyone have info about solar pumps or 200-300W 12V electric motors please let me know.

thanks

smallville · 45 Re: Solar Power Info for small off grid system Fri Jan 10, 2014 8:13 am

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I have few details to ask.. This system of Expert's I think cost a lot, 2KW with 250x8 panels cost a lot too.. So since ur battery is 3.5KW capable, I think still ur able to get more than 2KW when the day light is high I guess? correct me if i'm wrong..

how would a 200W panel, invertor, deep cycle battery, charger controller, cables and the fittings cost?

And where you can get good quality above stuff for a reasonable price?

Chinwi, I didnt get this water pump thing.. This is earth water ur taking about right? U want to pump water using a solar-powered motor I guess..
But does this earth water clean?

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Solar Power Info for small off grid system

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