The Expandable Solar Power System (Plug and Play)

[sensij]

But if there's so many flaws in my article, why can't people answer my questions?

Before trying to answer any of your questions, please answer one for me. In your own words, what is the difference between power and energy? Much of what you've written suggests you don't know, and without that fundamental in place, nothing else matters.

[Maitland Gill]

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But if there's so many flaws in my article, why can't people answer my questions?

[solar pete]

If Amps is a meaningless number, then why is it shown here as the Capacity? http://www.federalbatteries.com.au/8G4D/
Don't different Batteries have different capacities? How do we know the length of time that a certain percent of a Batteries capacity will last for?



I live in Australia. And these calculations are for running an air-pump 24/7, not to be based on average household usage.



The Battery I chose is a Gel-type. Because the system is designed to be slowly built up over time, the Batteries will be discharged and recharged many times, as it automatically switches between Solar and the Grid. This is why the PentaMetric is set to turn on the Relay when the Batteries SOC is at 85%, making the Batteries last longer.



I already know that, I explained it in the article (Some words have a faint line beneath them, showing that you can hover your cursor over them for a pop-up).

Hello Maitland Gill and welcome to solar panel talk, sounds like you have many flaws in your assumptions and I am not comfortable about that thing being linked to our site so I will consult with the others but may delete the link or the thread, cheers

[Maitland Gill]

Forget Amp Hours it is a meaningless number and is only a conversion after all calculations are concluded. It is the end result. Otherwise you end up making huge errors

You work with Watt Hours. A battery system capacity is rated for 5 days or 20% daily discharge with only 50% of the capacity is useable so net result is really 2.5 days usable.

If Amps is a meaningless number, then why is it shown here as the Capacity? http://www.federalbatteries.com.au/8G4D/
Don't different Batteries have different capacities? How do we know the length of time that a certain percent of a Batteries capacity will last for?

So if you use the national average of 30 Kwh per day requires a 150 Kwh battery.

I live in Australia. And these calculations are for running an air-pump 24/7, not to be based on average household usage.

It also weighs in around 900 pounds and requires a very expensive spill containment, EPA permit and yearly inspections.

The Battery I chose is a Gel-type. Because the system is designed to be slowly built up over time, the Batteries will be discharged and recharged many times, as it automatically switches between Solar and the Grid. This is why the PentaMetric is set to turn on the Relay when the Batteries SOC is at 85%, making the Batteries last longer.

Almost forgot, to find battery AMP Hours = Watt Hours / Battery Voltage. Example that 150,000 wh / 48 volt battery = 3125 AH. Simple 5th grade math. It would require at least a 15,000 watt solar panel system to charge them.

I already know that, I explained it in the article (Some words have a faint line beneath them, showing that you can hover your cursor over them for a pop-up).

[sensij]

Welcome to Australia...

Also, while this is off-topic, I heard the Central Bank in America is going to raise the rates on Monday. So I suggest you buy some Silver before inflation goes up.

Ummm... looks like your price is about the same as mine, $0.25 / kWh. I think you've made a major mistake in your plan, and hope you haven't bought anything yet.

http://www.energyaustralia.com.au/residential/electricity-and-gas/plans?cid=ret|int|ea|oo|cp|

[Sunking]

But then how else do we determine the number of Ah that a battery can give out at a desired percentage?

Forget Amp Hours it is a meaningless number and is only a conversion after all calculations are concluded. It is the end result. Otherwise you end up making huge errors

You work with Watt Hours. A battery system capacity is rated for 5 days or 20% daily discharge with only 50% of the capacity is useable so net result is really 2.5 days usable. So if you use the national average of 30 Kwh per day requires a 150 Kwh battery. Simple as falling off a log and 5th grade math. A good 5 year 150 Kwh battery cost $33,000 today and cost more in 5 years when you replace it. It also weighs in around 900 pounds and requires a very expensive spill containment, EPA permit and yearly inspections. So in the end more like $45,000 to S 50,000. If you had bought the same power form the utility in 5 years only cost you $10,000 to $15,000. Not only will you piss away a ton of money, you have also become a very heavy polluter and wasted a ton of energy and resources. You are so far off, it is really funny. So now you know why we are laughing at you.

Almost forgot, to find battery AMP Hours = Watt Hours / Battery Voltage. Example that 150,000 wh / 48 volt battery = 3125 AH. Simple 5th grade math. It would require at least a 15,000 watt solar panel system to charge them.

[Sunking]

Are you saying that the Batteries would not last long enough to make up for what they cost?

Yep and coupled with your huge errors.

[Maitland Gill]

i have to agree with sunking and sensij on their comments.

You DO NOT have a grasp on the basic math or units you are throwing about. You can't call Amps AmpHours because you need to use Ah someplace else.

You do not feed 96V into any inverter because it's a round number for math someplace else.

Are you saying that the notion of (183 Ah / 20 hours = 9.15 Ah) is wrong?
But then how else do we determine the number of Ah that a battery can give out at a desired percentage?

[Mike90250]

i have to agree with sunking and sensij on their comments.

You DO NOT have a grasp on the basic math or units you are throwing about. You can't call Amps AmpHours because you need to use Ah someplace else.

You do not feed 96V into any inverter because it's a round number for math someplace else.

I said: "the Inverter (Being the load) will need to be able to receive an input of 96 Volts DC | 9.15 Amps"
(96 Volts DC x 9.15 Amps = 878.4 Watts per hour)

Gel batteries are not suitable for solar applications, AGM batteries are, but are quite expensive.

You will have a mighty surprise when you connect batteries to the solar inputs of of the MPPT controllers,
no matter how good your intentions are.

You can build it, and it will smoke badly. Or just plain stink when it all melts down.

You have a bad habit of transposing units and devices around, so much it's really impossible to list all of what is wrong, here is my list of what is right.
2 x Schneider Electric MPPT 80 600 Solar Charge Controllers = $3,799.32

there may be more, but I advise you to label your web page as a DRAFT and I do not recommend anyone build it yet.

[foo1bar]

I want to keep the Ah, even if it's not how people normally do it, because it makes sense and is requied for the other calculations.

It doesn't make sense.
And if you're using that value with "Ah" as the unit in another calculation with that value as the input, then you must be doing something wrong in that calculation too. AmpHours/Hours = Amps. Or at the very least "Ah/h".

If you're not showing the right units in your calculations it makes me believe you're sloppy elsewhere in your calculations.

[Maitland Gill]

(183 Ah / 20 h = 9.15 Ah is wrong. 183 Ah / 20 h = 9.15 A is right).

I want to keep the Ah, even if it's not how people normally do it, because it makes sense and is requied for the other calculations.

this units in this statement are nonsense: "requires 132 Watt-Hours at 0.52 Amps per hour (Or 2,112 Watts for 16 hours)."

If two of the three measurements of electricity (V | A | W) are known, the third can always be found. But Electricity, being similar to light, needs a value of time, otherwise these numbers become meaningless.

I did change the Watts into Wh though: "(120 Wh - 10% efficiency = 12 Wh) + (120 Wh) = 132 Watt-Hours"

This statement is also hard to understand: "The Inverter needs to be designed for an Input of at least 878.4 Watts (96 Volts DC x 9.15 Amps = 878.4 Watts per hour)"

The load on the inverter is 132 W. The 9.15 A comes from the 20 hr discharge rate on the battery, but if you don't have loads that require it, there is no reason to size the inverter so large.

I said: "the Inverter (Being the load) will need to be able to receive an input of 96 Volts DC | 9.15 Amps"
(96 Volts DC x 9.15 Amps = 878.4 Watts per hour)

The air-pump requires 132 Watt-Hours, which makes the Amperage larger (132 Watts / 240 Volts = 0.55 Amps per hour), so I'll need to change that.
But are you saying that an Inverter that's rated for 200 Watts will be able to have a larger Input of 3.66 Amps at 240 Volts per hour flow through it?
So its ok as long as the Amperage rating is up to standard?

The battery you selected is 183 Ah * 12 V = 2196 Wh, at the 20 hr discharge rate (9.15 A). However, your discharge rate would be expected to be more like 132 W / 12 V = 11 A / 2 banks in parallel = 5.5 A

Won't the Inverter supply the number of Amp-hours as they're needed?

At our pricing, the 2.1 kWh of energy to run the pump is less than $0.50 / day. Do you really live somewhere that energy costs 20X that?

Welcome to Australia...

Also, while this is off-topic, I heard the Central Bank in America is going to raise the rates on Monday. So I suggest you buy some Silver before inflation goes up.

[Maitland Gill]

I am typing slowly so you understand. There is no ROI on a battery system.

If you believe there is an ROI on a battery system, I have one heck of a investment you will love. It works like this; you give me $100 today, and in 5 years I give you $25 back. You will be so happy with that deal you will give me another $100 for 5 years. Both of us will be tickled pink.

Anything you invest today in an off grid system is money lost forever never to be recovered. All you are doing is fooling yourself throwing money away when you should be saving it.

Are you saying that the Batteries would not last long enough to make up for what they cost?

[sensij]

I really like what you've done with detailing out the design and thought process that went into it. With a few more iterations, it could be a good reference for others wanting to follow in your footsteps.

However, there are a *lot* of errors. Some are just minor unit errors (183 Ah / 20 h = 9.15 Ah is wrong. 183 Ah / 20 h = 9.15 A is right).

Some are more significant, for example, this units in this statement are nonsense: "requires 132 Watt-Hours at 0.52 Amps per hour (Or 2,112 Watts for 16 hours)."

That pump is listed at 120 W. Somewhere you've applied a 10% factor to come up with 132 W. 132 W * 16 hours = 2112 Wh. "Amps per hour" and "Watts per hour" don't mean what you seem to think they do. Watts is power. Watt-hours is energy. You will need to understand the difference to really correct what you've written.

This statement is also hard to understand: "The Inverter needs to be designed for an Input of at least 878.4 Watts (96 Volts DC x 9.15 Amps = 878.4 Watts per hour)"

The load on the inverter is 132 W. The 9.15 A comes from the 20 hr discharge rate on the battery, but if you don't have loads that require it, there is no reason to size the inverter so large.

Your battery sizing section is kind of a mess. You want to supply 2112 Wh daily, bumped up to 2323 Wh to account for some battery loss, with discharge of only 15%. That requires 15488 Wh of battery capacity. The battery you selected is 183 Ah * 12 V = 2196 Wh, at the 20 hr discharge rate (9.15 A). However, your discharge rate would be expected to be more like 132 W / 12 V = 11 A / 2 banks in parallel = 5.5 A, so might get a little extra capacity, but you are still pulling more than the 100 hr rate, which has 210 Ah capacity (210 Ah / 100 hr = 2.1 A).

Let's stop here... buying 8 of these batteries (at >$8000) to create two 48 V banks in parallel is silly, even before you look more closely at the limitations of gel batteries. A better choice would be to build a single string of batteries with the necessary capacity... 15488 Wh / 48 V = 323 Ah. The Trojan L16RE-A is a 6 V battery with 325 Ah at the 20 hour rate. 8 of those gets you 48 V * 325 Ah... perfect. You can get them for around $300 ea, so your initial battery cost is only $2500.

Based on the above, there are probably errors in the solar panel sizing section as well, but this is enough for now.

Edit:
in the payback section:
If 1 kW per hour costs $5.87 and the 16 Solar panels produce 2.08 kW per day, then $12.20 is removed from the electric bill each day.
($5.87 x 2.08 = $12.20)

I think you've badly misunderstood the price of grid electricity. Here in southern california, running 1000 W for 1 hour results in 1 kWh of energy consumption. 1 kWh costs about $0.20.

At our pricing, the 2.1 kWh of energy to run the pump is less than $0.50 / day. Do you really live somewhere that energy costs 20X that?

[Sunking]

There are two differences.

(1) The cost of this system and the time until we get a Return On Investment.

(2.) Compared to the time it takes for us to save up so we can afford a Grid-tied system and get a Return On Investment.

I am typing slowly so you understand. There is no ROI on a battery system.

If you believe there is an ROI on a battery system, I have one heck of a investment you will love. It works like this; you give me $100 today, and in 5 years I give you $25 back. You will be so happy with that deal you will give me another $100 for 5 years. Both of us will be tickled pink.

Anything you invest today in an off grid system is money lost forever never to be recovered. All you are doing is fooling yourself throwing money away when you should be saving it.

[Maitland Gill]

Makes no difference whatsoever. Battery cost alone wile be 3 to 5 times higher than the mean ole power company will charge you. You just volunteered a 400% or maore increase in electricity silly. You will never have an ROI.

There are two differences.

(1) The cost of this system and the time until we get a Return On Investment.

(2.) Compared to the time it takes for us to save up so we can afford a Grid-tied system and get a Return On Investment.