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Tony
29th October 2012, 13:07
Help needed with solar panel -battery.


I bought a 145W 8.15A solar panel, plus a 1000W inverter.

Does anyone know what sort of battery I should use with it?
It seems that ordinary leisure batteries do not like being drained below 50%.

Basically I want it to operate a 240 volt. 100/140 Watt. slow cooker.
Is this possible?



Thanks,
Tony

Lovespot
29th October 2012, 13:23
Help needed with solar panel -battery.


I bought a 145W 8.15A solar panel, plus a 1000W inverter.

Does anyone know what sort of battery I should use with it?
It seems that ordinary leisure batteries do not like being drained below 50%.


Basically I want it to operate a 240 volt. 100/140 Watt. slow cooker.
Is this possible?



Thanks,
Tony

You need deep cycle batteries for that.

Possible, yes, considering the inverter has a 240 volt outlet.

Lifebringer
29th October 2012, 13:59
I believe it's lithium or either nickle batteries that are rechargeable, also check for auto shut off device if the unit is fully charged and on safe levels. If the converter reverts back to the grid, then that's a plus and turns the meter backwards, but when a power outage occurs, there must be a shut off because of back up or over charge. The sun will come out on time, but Electric Company comes according to need. You don't want the grid to revert and steal your power, and when the grid is reactivated, the surge could blow the system, so check it out with engineer even if you have to call one for consult or online chat, and ensure the safety of the equipment with that knowledge.

I am a LEED Green Energy Efficient Associate, but a LEED LP can help you with installation and rechargeable options. I myself specialize in building construction and energy efficient equipment, and rejuvenation of soils from run off and or gardening on clay or sandy soil. I build garden boxes for people's property that has lots of tree roots, that cannot be grinded up with a tiller, because the tiller won't be able to till, but will break.

A garden box is easier to maintain for the elderly, and apt living with a balcony. Fresh veggies and fruit bushes like strawberries. City bees, wasps, and butterflies, don't mind.

Let your fingers do the clicking and God speed on your journey to energy independence.

Tony
29th October 2012, 14:56
Thanks Lovespot and Life bringer,

If this small systems works I will expand it.



Tony

wavydome
29th October 2012, 15:12
One needs to distinguish between committed-well-funded-buyers vs the the low income do-it-yourselfer like me. My post is for the miser. Well funded buyers ought to get full installation service. I spent more than i should have and am not encouraged with solar electric systems, (even as a skilled do-it-yourselfer).

Lead-acid types are clearly the most affordable types,for home backup. Getting use from them, (when the grid is working), is also problematic and time consuming. There are energy losses from DC to AC conversion as well, (besides the aging). So cutting up some LED string lights, to match the battery voltage, is the best deal for emergency lighting circuits, IMHO-- (Sectioned for more than one place in one's dwelling)....

Deep cycle (lead acid) have smoother plates inside which increases durability and somewhat decreases surge power capacity (like starting a car). Deep cycle batteries have long been manufactured for marine and for off road use and have many manufacturers.

I'm just about to restore some connections on my highly promoted deep cycle brand for home-solar.... So this thread encouraged me to rant. a little. Batteries are troublesome, especially if little used. All types are troublesome, not just lead acid.
I sort of wish i had gone with ordinary best-deals, no frills... Not even a controller, just use a very cheap Schottky diode to stop night time leakage...

I bought a leading solar type lead-acid 2 years ago... I'm actually not impressed. There have been no problematic power outages. Only the possible calamities remain as justification for my big purchases including a fancy controller.

One almost needs to take an accurate voltmeter, right to the store, for best results, in choosing a battery. Self service stores should allow this and likely re-charge stocked batteries on a regular basis-- So the highest voltage units might likely be the best., (decimal values implied here). In the old days, one would fill the acid into empty-new-batteries... This ensured the maximum possible battery life. (I kept asking for empties, when purchasing over the years... These are gone.)


Although, separately i did buy a small AMG type of lead-acid battery-- This type also is supposed to be more durable, most notably for stand-by uses like back-up. It holds up well but these have been less manufactured and therefore cost more.

From a very low cost perspective, my own car batteries have been great for emergency backups, good enough... So far, solar-electric power has been disappointing, i'd have to say.

Ron Mauer Sr
29th October 2012, 16:00
Help needed with solar panel -battery.


I bought a 145W 8.15A solar panel, plus a 1000W inverter.

Does anyone know what sort of battery I should use with it?
It seems that ordinary leisure batteries do not like being drained below 50%.

Basically I want it to operate a 240 volt. 100/140 Watt. slow cooker.
Is this possible?



Thanks,
Tony

Tony,

Yes, what you want to do is perfectly reasonable.

A deep cycle lead acid battery designed for golf carts, marine use or solar applications is the most cost effective. To get maximum battery life it is best not to discharge the battery to less than 50% full. Your inverter may have a low voltage cut out that disables the inverter if battery voltage goes below a certain threshold. The larger inverters I have used to power two houses have all had that feature.

You may want to consider purchasing a charge controller to limit battery charge current when the battery is fully charged. If a lead acid battery is overcharged, water will be boiled out/evaporated. Keep a frequent check on the battery water level if you choose not to use a charge controller.

You need to match the solar panel working voltage to the battery voltage. Placing batteries in series increases the system voltage. For example if your solar panel is designed for 12 volts, you will need two 6 volt batteries in series, or one 12 volt battery. Additional batteries can be added in parallel to increase system storage capacity.

It is important not to use automobile batteries for a solar system because they are not designed for deep discharge. Even though the purchase price for automobile batteries is less than deep cycle batteries, automobile batteries are the most expensive to put in a solar system due to early failure.

Ammit
29th October 2012, 16:41
And dont forget when you choose your batteries to get the biggest amp/hr type you can. If you work out what amps you need per hour and then double it then you have a good starting point to choose how many batteries you need. I have found that if you only use half of each battery then you can keep them working fine, but, as said above never fully drain them.

ghettogether
29th October 2012, 16:46
http://www.sportsimportsltd.com/12voslco.html Hey tony, you would get your best mileage out of the project by finding something with a DC heating element, that way, you get around the power loss of the inverter, which is also a "slow cooker", every time you transform energy dc/ac you lose it, what single panels are probably the best for is (especially led) lighting and low-power draw electronics, although intermittent cooking would be a cool application.

Tony
29th October 2012, 18:58
Wow, now this is what a forum is for!

Thanks all....I've just got to shove my fingers in a socket to see how it feels!



Tony

Arrowwind
29th October 2012, 19:49
We have an electric pump on our household well and an electric pump for our irrigation water. I am looking for a solar system that these two pumps can run off of. I expect that each pump will have its own system as they are quite far apart from each other.

any links or product info would be appreciated. We really arn't do it you selfers when it comes to these kind of things.

bodhii71
29th October 2012, 20:34
Just don't forget the battery matainance. Nothing as scary as having one of those blow up near you. +1 for LED idea even if it is used in conjunction with another system.

Lazlo
30th October 2012, 01:33
Help needed with solar panel -battery.


I bought a 145W 8.15A solar panel, plus a 1000W inverter.

Does anyone know what sort of battery I should use with it?
It seems that ordinary leisure batteries do not like being drained below 50%.

Basically I want it to operate a 240 volt. 100/140 Watt. slow cooker.
Is this possible?

Thanks,
Tony

Doing the math here (P=IV) you have a 17.79V module. You would normally want around 14V to directly charge a 12V battery. The module you have was likely intended to be used in series to operate a grid tied inverter as part of a string operating at higher voltages.

Some basic principles of PV modules. The nameplate is based upon STC = Standard Test conditions. In reality, your module will almost never operate at these conditions. STC is 1000 w/m2 (irradience) and 25 deg c module temperature.

Voltage is dependent upon temperature. Higher temperature = lower voltage and lower temperature = higher voltage

Current is dependent upon irradience. The intensity of the sunlight.

You should be OK with this module but I would suggest that you get a charge controller to keep the voltage optimized for charging and to float when the battery is topped off. I would think that you can find a controller for $30 USD or so if you dig around. I think that someone else mentioned that you will boil off the battery of the voltage is too high.

You are not going to be able to cook much of anything with a single battery system. I'd hate to see you disappointed and disillusioned with PV. I don't think that anyone else has mentioned this. It goes back to Ohm's law. Look at the label on the cooker that you want to use. It will be labeled with how many amps the cooker uses when in operation. I expect that you will find that the battery won't heat the oven long enough to cook anything.

You can PM me and I'll be happy to help you with the math and come up with a solution that you will be happy with given your budget.

Deep cycle batteries are a requirement, and if you don't want to pay too much attention to them, go with a sealed gel style battery. These are sometimes called maintenance free batteries.


Disclaimer: I work with utility scale PV. My plants operate at 600-1000V on the DC side and step up to anywhere between 480 and 320,000V on the AC size and are rated in the MW range. The largest being 146 MWp. It's enough to power a city of around 40,000 people.

I don't spend a lot of time thinking about small systems, but I do understand how the technology works ;)

Lazlo
30th October 2012, 01:37
We have an electric pump on our household well and an electric pump for our irrigation water. I am looking for a solar system that these two pumps can run off of. I expect that each pump will have its own system as they are quite far apart from each other.

any links or product info would be appreciated. We really arn't do it you selfers when it comes to these kind of things.

In order to size the systems, it is first necessary to know how much water you need to pump, and then the nameplate info for the pumps.

I'll throw at the same offer. PM me and I'll be happy to help, or if you prefer we can trade posts here so that other people might be assisted as well.

I'm travelling this week so the replies might not be terribly fast, but I promise to pay attention.

Arrowwind
30th October 2012, 02:00
[
In order to size the systems, it is first necessary to know how much water you need to pump, and then the nameplate info for the pumps.
I'm travelling this week so the replies might not be terribly fast, but I promise to pay attention.

What do you mean by nameplate? I'll have to ask my DH about water needs.

Lazlo
30th October 2012, 03:02
[
In order to size the systems, it is first necessary to know how much water you need to pump, and then the nameplate info for the pumps.
I'm travelling this week so the replies might not be terribly fast, but I promise to pay attention.

What do you mean by nameplate? I'll have to ask my DH about water needs.


On the pump will be a label, maybe a metallic one, that will list the characteistics of the pump, such as GPH (gallons per hour) Voltage, Current, model number, serial number, etc.

The only numbers you really need are the first three I listed.

You first need to figure out how much power the pump requires. IE, voltage and current (current will be listed in amps)

With the gallons per hour and the amount of water you need daily, it is then possible to determine how many PV modules, batteries, and what size inverter you need.

Carmody
30th October 2012, 03:57
Help needed with solar panel -battery.


I bought a 145W 8.15A solar panel, plus a 1000W inverter.

Does anyone know what sort of battery I should use with it?
It seems that ordinary leisure batteries do not like being drained below 50%.

Basically I want it to operate a 240 volt. 100/140 Watt. slow cooker.
Is this possible?

Thanks,
Tony

Doing the math here (P=IV) you have a 17.79V module. You would normally want around 14V to directly charge a 12V battery. The module you have was likely intended to be used in series to operate a grid tied inverter as part of a string operating at higher voltages.

Some basic principles of PV modules. The nameplate is based upon STC = Standard Test conditions. In reality, your module will almost never operate at these conditions. STC is 1000 w/m2 (irradience) and 25 deg c module temperature.

Voltage is dependent upon temperature. Higher temperature = lower voltage and lower temperature = higher voltage

Current is dependent upon irradience. The intensity of the sunlight.

You should be OK with this module but I would suggest that you get a charge controller to keep the voltage optimized for charging and to float when the battery is topped off. I would think that you can find a controller for $30 USD or so if you dig around. I think that someone else mentioned that you will boil off the battery of the voltage is too high.

You are not going to be able to cook much of anything with a single battery system. I'd hate to see you disappointed and disillusioned with PV. I don't think that anyone else has mentioned this. It goes back to Ohm's law. Look at the label on the cooker that you want to use. It will be labeled with how many amps the cooker uses when in operation. I expect that you will find that the battery won't heat the oven long enough to cook anything.

You can PM me and I'll be happy to help you with the math and come up with a solution that you will be happy with given your budget.

Deep cycle batteries are a requirement, and if you don't want to pay too much attention to them, go with a sealed gel style battery. These are sometimes called maintenance free batteries.


Disclaimer: I work with utility scale PV. My plants operate at 600-1000V on the DC side and step up to anywhere between 480 and 320,000V on the AC size and are rated in the MW range. The largest being 146 MWp. It's enough to power a city of around 40,000 people.

I don't spend a lot of time thinking about small systems, but I do understand how the technology works ;)

I found a way to discharge batteries that makes them last notably longer when discharging....and a way to get more power from the panels.

Unloaded vs loaded panels.

If you pulse discharge the panels in the megahertz range, you get a draw curve, over time. Similar to that of a capacitor curve. The drop from no load voltage to load voltage is not instantaneous...

But the return to no load voltage, in the semi conducting material of the panel itself IS instantaneous. Parallel increase at the molecular level on disconnect, molecular series drop and capacitor like time curve on the drop, on draw.

Find the magic frequency..and the power output increases.

One tiny problem. Well, a big problem, potentially.

It may work like a planar (2d) orgone/scalar generator.

Experiment, but watch for it.

If it erupts into an apparent over unity situation, don't be surprised. After all... it is a 'semi' conductor, at the molecular level, and it inherently lives in a state of elastic near resonance.

Think of Tom Bearden's solid state (transistor or 'semiconductor') over-unity experiments and devices. except...on a grand physical 'planar' scale. That's one heck of a lot of semi-conductor material, in a given cell. It would probably have to be tuned for it's physical location, as well. meaning, if it works and is moved and then it doesn't work for some reason, it probably will need to be tuned to the local dark matter situation.

Read posts 182 and 183,and proceed to the link to the layered bismuth aluminum device, and it should be clear, at that point.


http://projectavalon.net/forum4/showthread.php?17872-The-Question-of-Lithium--Alchemy-dimensions-shapeshifters-aliens-existence-reality..-&p=576114&viewfull=1#post576114

Understand that we are talking about inherent dark matter, the dimensional fabric of linear time and 3d reality formation..and interruption of such flow, can create it's own interference pattern, so this may be a dangerous pursuit. Localized distortions, and what not. Remember Tesla's experiments and associated resonance..and what can go wrong. Such a thing is an 'open' system and the effects could be unpredictable, without the correct background knowledge. It could (and probably will) be like sticking a potent resonant reed in a flow system..and the effects are partially unpredictable to the uneducated and unaware person or group.

Tony
30th October 2012, 08:29
Well, thanks fellows for your knowledge, I'm sure your information will encourage others to have a go!


Tony

Lifebringer
30th October 2012, 13:44
Edbagley.org may help. He explains solar everything in detail for us misers. I'm working on home made filtration using triple coffee filters and or cloth also gravel, pebbles silt, and sand scalded with hot water to clear all bacterial residues, and then plan to capture some water since they are gonna charge per flush or dish washing water. Boiling it always helps before refeeding the water, into a final filter in the home from Purilator. Gotta store as much while it's good. Did you notice that everytime this allignment happens, the earth opens and swallows the water before scorching and the water inside the planet is then returned. I'm trying to figure out how that will occur, but it's in everyone of the stories around the world about the earth opening up and swallowing the waters.

Buckle up people, Creator means to carry out what was planned. Get your minds right, and love everyone unconditionally because we are all humans and deserve the respect in live as we experience this "caccoon life."

Then again, perhaps this time the poles will attract with one of the planets in the Nibiru solar system, and take us away with it in gravity force, instead of destroying the planet, or removing another moon.

wavydome
30th October 2012, 14:10
We have an electric pump on our household well and an electric pump for our irrigation water. I am looking for a solar system that these two pumps can run off of. I expect that each pump will have its own system as they are quite far apart from each other.

any links or product info would be appreciated. We really arn't do it you selfers when it comes to these kind of things.

Arrow, When i was ready to buy our "improved solar system", i found this forum had the most helpful members and posts:
http://www.wind-sun.com/ForumVB/forum.php?
I recommend searching for the therms of interest, as a first step. Self education is vital, even if you do hire some contractor or hire some full-service-outfit. PV systems can ultimately equal the cost of one's car, brand new. Redesigning one's lifestyle is another option.

The associated sponsor of the above forum also had the best listed pricing (for same brands) 2 years ago except that i saved due to shipping costs by finding another source here on the east coast... Web searching gets boring, but wrong expenditures are worse.

BTW, i chose my own system based on your-described-criteria: Pumping water may indeed become the biggest energy user-- (Assuming one is not spending megabucks for larger-demanding uses like cooking ranges or HAVC, ouch). So you need to predict the well depth in dry periods, and then learn how much energy draw is needed (in watts) to pump the required amount of water, per day or per period of interest, etc.... Gravity-powered-water storage tanks become very interesting, to save money. I have used a 150 gal tank for years prior, for solar heated water which also doubles over as general water supply in outages.
my system: http://harmoniouspalette.com/SolarWater/SimpleSolarWater.html

PV is an extremely complex issue to be sorted out, based on lifestyle and location, location, location...

So that a good forum is a great place to scan through focussed details.

~wav

Ron Mauer Sr
30th October 2012, 18:15
Help needed with solar panel -battery.


I bought a 145W 8.15A solar panel, plus a 1000W inverter.

Does anyone know what sort of battery I should use with it?
It seems that ordinary leisure batteries do not like being drained below 50%.

Basically I want it to operate a 240 volt. 100/140 Watt. slow cooker.
Is this possible?



Thanks,
Tony

Estimates of energy captured by the solar panel:
Best case energy from the summmer sun, 5 hours of peak sunlight
Non-tracking solar panel captures 75% of available energy due to suns movement.
Yields (145*5*0.75) = 544 watt hours

Useable stored energy (50% of maximum capacity) in two 6 volt T105 deep cycle batteries connected in series to make 12 volts = 220 amp hours * 50% = 110 amp hours
110 amp hours * 12 volts = 1320 watt hours

Note: If you use 1320 watt hours it will take more than two days to return the batteries to full charge. (1320/544=2.42 days, ignoring system losses)

Assuming a system efficiency of 85% (15% lost as heat) the useful energy output of the inverter is 1122 watt hours.

With the crock pot set for 140 watts, and limiting battery depletion to 50%, this would allow a cook time of 1122/140 = 8 hours.

If you cooked every day in bright sunny summer skies, you would be limited to the daily solar energy input of 544 watt hours to maintain the same battery charge at the end of each day.

This means that if every summer day has 5 hours of peak sunlight, you are limited to 544 watt hours of using your crock pot, or 544/140 = 3.89 hrs, or 3 hours and 50 minutes.

Of course we never have bright summer days at anyplace I know of, so you will need to adapt.

A solar oven (http://ronmauer.net/blog/?page_id=557) will save battery charge, and a wood fired camp stove (http://ronmauer.net/blog/?page_id=669) will work in the dark. Redundancy is your friend.

Tony
30th October 2012, 18:30
Help needed with solar panel -battery.


I bought a 145W 8.15A solar panel, plus a 1000W inverter.

Does anyone know what sort of battery I should use with it?
It seems that ordinary leisure batteries do not like being drained below 50%.

Basically I want it to operate a 240 volt. 100/140 Watt. slow cooker.
Is this possible?



Thanks,
Tony

Estimates of energy captured by the solar panel:
Best case energy from the summmer sun, 5 hours of peak sunlight
Non-tracking solar panel captures 75% of available energy due to suns movement.
Yields (145*5*0.75) = 544 watt hours

Useable stored energy (50% of maximum capacity) in two 6 volt T105 deep cycle batteries connected in series to make 12 volts = 220 amp hours * 50% = 110 amp hours
110 amp hours * 12 volts = 1320 watt hours

Note: If you use 1320 watt hours it will take more than two days to return the batteries to full charge. (1320/544=2.42 days, ignoring system losses)

Assuming a system efficiency of 85% (15% lost as heat) the useful energy output of the inverter is 1122 watt hours.

With the crock pot set for 140 watts, and limiting battery depletion to 50%, this would allow a cook time of 1122/140 = 8 hours.

If you cooked every day in bright sunny summer skies, you would be limited to the daily solar energy input of 544 watt hours to maintain the same battery charge at the end of each day.

This means that if every summer day has 5 hours of peak sunlight, you are limited to 544 watt hours of using your crock pot, or 544/140 = 3.89 hrs, or 3 hours and 50 minutes.

Of course we never have bright summer days at anyplace I know of, so you will need to adapt.

A solar oven (http://ronmauer.net/blog/?page_id=557) will save battery charge, and a wood fired camp stove (http://ronmauer.net/blog/?page_id=669) will work in the dark. Redundancy is your friend.



That is really helpful thanks. I just love the idea of cooking by sunlight...and giving nothing to the corporations!



Tony

Tony
2nd November 2012, 20:05
Hello Battery enthusiasts!

I've ordered my batteries, so next week it's free electricity! .. we'll be eating from a slow cooker from now on!

Thanks again for all your help....I will get back to you, when it all goes wrong.


Tony

Ron Mauer Sr
2nd November 2012, 20:40
Hello Battery enthusiasts!

I've ordered my batteries, so next week it's free electricity! .. we'll be eating from a slow cooker from now on!

Thanks again for all your help....I will get back to you, when it all goes wrong.


Tony

Congratulations Tony.

Let us know your favorite off the grid recipe.

Ron

Anchor
2nd November 2012, 22:09
Disclaimer: Australian (we have more sun than you ;) )

Apart from the A/C, my farm has the potential to operate off grid and solar powered.

The system to do this was costly, and any system like this contains consumables - batteries.

So now the new name of the game is managing the battery health to get the most out of them. Batteries designed for off-grid use are often capable of lasting 25years but if you do not look after them they can be wrecked quickly.

The most important thing for a system that is in regular use is to ensure that the batteries stay charged, or as fully charged as possible.

Oddly, the trick is actually to avoid situations where the batteries get much use - ie: taking power when the sun isnt shining. Do all your washing and cooking when the sun is providing the power, so you don't get it from the batteries.

If you do need to use the batteries, then they must be efficiently recharged as quickly, as soon and accurately as possible.

Doing this from home generation (solar, water-wheel power, wind power ) requires the best quality and most efficient charge controller you can afford. (Here is the kind I use, http://www.solaronline.com.au/outback-fm80-mppt-solar-regulator.html - my system is 24v, so with two I can control around 4kw of panels). I chose 24v because that meant I can write the ELV side myself. A 48V system in Australia has a charge voltage over 50V and the rules here mean I need an electrician for that ;) The higher the voltage on the battery side the easier it is to reduce wiring losses - this is more relevant for larger systems - not camping sized systems like the one Tony is talking about.

For solar, the best kind of technology currently is a type called MPPT (Maximum Power Point Tracker) http://en.wikipedia.org/wiki/Maximum_power_point_tracking. These contain switch mode converters that 'harvest' the greatest amount of power from the panels by varying the load characteristics presented by the controller to the panels and converting the power to exactly what is required by the battery. These devices are programmable and should be configured to use the correct charge profiles required by the particular battery chemistry that you are using. On my system they ensure that (some) useful power comes from my panels even on overcast days.

Another tip if you can afford it, is to get more of solar panels than you think you will need. The charge controller(s) will deal with the excess, but you will be able to run your systems for longer during the day and get the batteries charged quicker.

Off grid solar sizing is not about how much power you use during the day, but how to get your batteries fully charged ASAP and keep them charged until needed - while providing power during the sun hours for your appliances. The size of the batteries is based on the assessment of how much you will need to use them based on a few days of no sun and your willingness or otherwise to use some kind of fuel based generator like diesel or petrol.

(For this reason, off grid systems are generally bigger than the kinds of systems that are being installed that sell power back to the grid.)

---
TL;DR get a good charge controller, do as much as you can when the sun is out, look after your batteries!

panopticon
3rd November 2012, 00:56
G'day Tony,

Just saw this thread so sorry for the late response...

What Amp hour battery system did you decide on?

As stated look after the batteries and connectors, and do as much as possible during sunlight hours!

Do you have an AMP meter connected to the system? A regulator? Some of the new PV systems may have this already.

For a battery to be charging it needs to be getting around 14 Volts from the panel/s (which, as others have already pointed out, is why a regulator is important so the batteries don't dry out).

LED lighting and having other options available (for cooking) are also excellent suggestions.

Also... Remember that panels and all their attachments (like LED globes) are susceptible to EMP's so Faraday away if needed. Oh, and here's a link to the excellent resource Bill uploaded a while ago:
http://projectavalon.net/EMP_Electromagnetic_Pulse_Protection.pdf




Doing the math here (P=IV) you have a 17.79V module. You would normally want around 14V to directly charge a 12V battery. The module you have was likely intended to be used in series to operate a grid tied inverter as part of a string operating at higher voltages.

Some basic principles of PV modules. The nameplate is based upon STC = Standard Test conditions. In reality, your module will almost never operate at these conditions. STC is 1000 w/m2 (irradience) and 25 deg c module temperature.

Voltage is dependent upon temperature. Higher temperature = lower voltage and lower temperature = higher voltage

Current is dependent upon irradience. The intensity of the sunlight.

You should be OK with this module but I would suggest that you get a charge controller to keep the voltage optimized for charging and to float when the battery is topped off. I would think that you can find a controller for $30 USD or so if you dig around. I think that someone else mentioned that you will boil off the battery of the voltage is too high.

You are not going to be able to cook much of anything with a single battery system. I'd hate to see you disappointed and disillusioned with PV. I don't think that anyone else has mentioned this. It goes back to Ohm's law. Look at the label on the cooker that you want to use. It will be labeled with how many amps the cooker uses when in operation. I expect that you will find that the battery won't heat the oven long enough to cook anything.

You can PM me and I'll be happy to help you with the math and come up with a solution that you will be happy with given your budget.

Deep cycle batteries are a requirement, and if you don't want to pay too much attention to them, go with a sealed gel style battery. These are sometimes called maintenance free batteries.


Disclaimer: I work with utility scale PV. My plants operate at 600-1000V on the DC side and step up to anywhere between 480 and 320,000V on the AC size and are rated in the MW range. The largest being 146 MWp. It's enough to power a city of around 40,000 people.

I don't spend a lot of time thinking about small systems, but I do understand how the technology works ;)

Spot on Lazlo.

Just to clarify on the ~18 Volt input (usually around 17.5 Volts I think) from the panel, I think this is correct for a small 12 volt system.

You are also spot on when you said that the reason this happens is that voltage output lowers as temperature of the cells/panel increases.

As you said the temperature this is measured at is 25 degrees C.
For every 20 degree rise in temp the loss in voltage is ~10%.
So at 50 degrees C the output would be somewhere between 14.5 & 15 Volts and at 75 degrees C it would be nearer 11 Volts.

The following illustrates this to some extent:
http://ecopia.com.au/image/SolarPanelOutputVtemp.JPG

There's heaps of information available on the interweb about what PV system to choose (here's one picked at random from a quick search):
http://ecopia.com.au/how-to-choose-a-solar-panel
Kind Regards, :yo:
Panopticon

Tony
12th November 2012, 10:06
Well, today 12th November 2012 at 10 am.........I have free electricity!
I HAVE THE POWER.
Well, enough to run a small appliance.

Thanks for all the help, some of it was a bit technical, and I had a few sparks, but the fingers are all intact!
I'll back for more information soon.


Yours digital,
Tony



(ps, Thank you Ron for the simple guidance!)

Tarka the Duck
12th November 2012, 12:16
Thanks to everyone on this thread for keeping my mate safe from vicious sparky things that could do him damage :eek:
Kathie xx

olddragon
12th November 2012, 12:19
I'm not really certain, but we have a marine battery for our caravan. It works well.

Tony
12th November 2012, 12:36
I have another question, if someone can explain simply.

Q. Is there a danger of drawing off too much power, ie putting on a too bigger appliance....what might happen?:mad2:

Robert J. Niewiadomski
12th November 2012, 13:08
I have another question, if someone can explain simply.

Q. Is there a danger of drawing off too much power, ie putting on a too bigger appliance....what might happen?:mad2:
Hi

Tony, Your bigger appliance will not work. Or will work awkwardly ;) There will be not enough juice... and nothing will be set on fire... If your inverter has a fuse/circuit breaker it will blew it ;)

Maybe it is a good idea to have additional fuse between inverter and your house with lower current cut-off rating... Ex. if your inverter has a 10A fuse, put another behind it with lower value of 8A...

I admit i am not an electrician. Have few opportunities of assisting my father (he IS an electrician) with installation projects... If i have not misunderstood something then i think Ernie Nemeth is a skilled electrician :) Maybe you should PM him Tony?

Ron Mauer Sr
12th November 2012, 13:58
Congratulations on a successful solar setup Tony.

What are you cooking?

Tony
12th November 2012, 14:32
Congratulations on a successful solar setup Tony.

What are you cooking?


Well, a beef stew... and the sun is not shining, the batteries are losing its numbers, still it works a lamp!

Onwards and upwards!

Ron Mauer Sr
12th November 2012, 15:02
Congratulations on a successful solar setup Tony.

What are you cooking?


Well, a beef stew... and the sun is not shining, the batteries are losing its numbers, still it works a lamp!

Onwards and upwards!

Some inverters will turn off if the batteries get discharged too much. The 12 volt system I used would shut itself off if the inverter input voltage fell below 11.5 volts.

If you use a 140 watt crock pot and a 145 watt solar panel, it will take more than 1 hour of direct sunlight for each hour of crock pot use because the system cannot be 100% efficient. If the system were 80% efficient it would take approximately 25% more solar charge time than cook time to recharge the batteries to the same level of charge they had when you started cooking.

Carmody
12th November 2012, 16:41
If one is going completely off grid, with a high powered system....one should consider the making of one's own lead-acid batteries.

To find out about plate design/build and cell design. Lead acid batteries, or batteries in particular, lead-acid in the specific...are one of the oldest and simplest technologies around.

Rolls, the battery people, are kind enough to share their physical plate layout with the public, through some informational videos. Then comes the plate ingredients. After that, it is plate connectivity and immersion systems. The batteries and the panels are the most expensive parts, and the batteries are a notable wear item. Thus.... knowing them inside and out, can be critical. Not simply technical specs, but build specs. To try and build one.

fourty-two
12th November 2012, 17:35
battery info facts
http://www.windsun.com/Batteries/Battery_FAQ.htm

Anchor
12th November 2012, 23:21
Most inverters I have tested work at their peak efficiency when just slightly under maximum load.

It is not usually a good idea to use say a 3000W inverter for a 100W load - if you do, you will probably see less than 80% efficiency. My 3000W inverter is most efficient when supplying between 1200W and the peak.

Another fact to consider is if you are charging batteries, and then running your load later when the sun is not out, your losses are compounded because your have to reckon with the inefficiency of the battery charging ( usually around 86% ).

Batteries take more power to re-charge than the power that they yield up on discharge - the difference is basically electrochemical conversion losses inside the battery.

Add it all together and it can start to look quite depressing:

1) Inverter losses
2) Charger losses
3) Battery losses
4) also to a smaller extent there are cabling losses.

These factors added together over time, and averaged out can mean you find that you need many more panels than you first thought if you were comparing panel wattage to load wattage, and consequently you may also need higher capacity chargers and charge controllers.

Most people who are seriously into camping will select DC appliances like fridges, tv's and microwave ovens etc - wherever possible to avoid the inverter conversion losses; this is easier said than done though because the wires for high powered low voltage appliances are very thick.

I have a 12V kettle that I can use in the car, but the cars circuit can only cope with 20A current, the kettle is therefore only 240W and takes 10 times longer to boil water than a house kettle - in Australia household appliances are generally limited to 10A at 240V maximum.

My off grid system however can run the house kettle, but when it is running and the sun is down, there is up to 120A flowing from the batteries which usually float around (27-28V) to the inverter. To carry that much current takes very thick cables - the ones I use have 50mm˛ of copper conductor. Even then they can get warm to the touch with prolonged use at high loads like this.

My new inverter is a 5000W inverter charger - and requires 100mm˛ conductors - (actually 2 x 50mm˛) to cope with peak currents of 500Amperes (at 24V).

At these kinds of loads you have to be very thorough about getting all the connections made well. If you don't you get hot spots, and even a fuse wont save you from the release of the magic smoke as the cables burn up their insulation.

I speak from hard won experience. Last year I found that I had not bolted down the fuse correctly and nearly burned my shed down.

That said, fuses on the battery cables are essential - they are there to save you from catastrophic failures like short circuits.

So please, if you are playing with this stuff, remember, batteries are dangerous, even smaller ones, and fuses (at the battery end of the cable) work very well mitigate the risk of serious damage - but they don't remove the risk of other kinds of failure.

Properly qualified help is worth having if you can get it.

panopticon
12th November 2012, 23:44
We run solar for lighting and small electrical loads (laptop etc) and natural gas for cooking.
Have a wind generator for when the sun isn't sufficient (living in Tassie that's half the year!).
When the load is too great on the inverter, or insufficient volts in the battery bank, it cuts out.
As others have said, I think this is what most inverters do now.
Kind Regards, :yo:
Panopticon