need explanation for some peace

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need explanation for some peace

Postby BeeMee » Wed Oct 30, 2013 10:00 am

Hope I have chosen the right area for this.
I need a simple explanation on how solar works for my husband who just does not get it. I am wasting my breath trying to explain so if the knowledge comes from someone in the know, then he is more likely to accept it.
All the following amounts are selected to simply the math.

We are putting in 20kWh per day and we use 12kWh daily.
My husband wants to know if we are using the solar primarily, then why does the bill come in as a fee?
Why isn't 12kWh taken off the 20kWh produced and so therefore there is only 8kWh we are paid for?
Are we running off the solar first or not? (words have been changed as his were very expletive). :evil:
Why are we still getting a bill for what we use if we are running off a solar?

He grasps the Net and Gross system and we are on Net.
Is there anyway to explain this so this house can have some peace finally?
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Re: need explanation for some peace

Postby LEDMAD » Wed Oct 30, 2013 12:10 pm

1) The excess power you generate isn't being stored for later use.
2) The sun doesn't shine at night, but you still use power during the night. As you have nothing stored you need to buy electricity.
3) The price you buy electricity at is MUCH higher that the price you can sell your excess at. So your excess generation counts for nearly nothing.
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Re: need explanation for some peace

Postby Tracker » Wed Oct 30, 2013 2:06 pm

LEDMAD wrote:1) The excess power you generate isn't being stored for later use.
2) The sun doesn't shine at night, but you still use power during the night. As you have nothing stored you need to buy electricity.
3) The price you buy electricity at is MUCH higher that the price you can sell your excess at. So your excess generation counts for nearly nothing.


and

You generate power whenever the sun shines..
It MUST go somewhere.. If you are NOT there to use it, it goes to the GRID, and you get little for it.

The more you use , especially around the middle of the day, the better off you are..

You can see on the inverter meter, just what you are generating at any time..
If you can USE that much, then you are using your own power... :D
If you use MORE, then you are buying their power, and obviously if LESS, then you are selling your power for very little, and then IMPORTing it at full price, when the sun sets.

PS..
We are putting in 20kWh per day and we use 12kWh daily.

This could suggest a few different scenarios.. either you have a smallish system and as no one is home during the day, most of the power is being wasted as EXPORT and the remaining 12kWh IMPORTed at night..
OR - it's a larger system and you are using a good deal anyway, during the day, and still use another 12 at night..
Don't forget how much power it takes with cooking.. :cry:
..
.
Retired Engineer and keen PV experimenter - Always ready to learn and share.
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Governments won't save the world :-) They will just TAX it :-(
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Re: need explanation for some peace

Postby BeeMee » Wed Oct 30, 2013 6:57 pm

I am taking this off our last bill to explain, because all these numbers give me a headache! These are based on a 3 month cycle.
Notes:
We are home 24/7
We have a whisker under 5kWh system.
We have a gas cooktop.

Tariff 11 total usage (with price rise included) 745kWh - Total price $241.86
Tariff 33 Total usage (with price rise included) 279kWh - Total price $51.61
Total combined with both Tariffs $293.47
Solar during the 3 month period has made 1086kWh and earnt us for that 3 months $477.84 before they take off the usage of $293.47 leaving us a credit of $284.60

So this 745kWh and the 279kWh is what is used at night then? Sounds a bit suspicious to me, simply because our Tariff 33 goes off in the morning at 7.30am and on again at 8.30am (bet that will change in summer). And also off again at night at 5.00pm till 10.00pm. Seems a lot of usage when the darn power is off for 6 hours per day AND we are in bed before 10pm as well, so no one is up with any more than the basics running (fridge).

I am not complaining by any means, as I am quite happy that I am not paying them and I have cut back as far as I can go so we don't blow out costs. And I know my usage and costs are way lower than many out there. But hubby can't seem to see it no matter how many times I explain it. Especially when our former bills without the solar grid is about the same amount in kWh. I am aware of the price changes and costs, so that will naturally increase, but the darn kWh per quarter should if the solar is feeding us from sunup to sunset. That's what my husband can't grasp.

Hope I have made this a little clearer.
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Re: need explanation for some peace

Postby Smurf1976 » Wed Oct 30, 2013 8:20 pm

Tariff 33 (which I assume you are using for hot water) is metered completely separately to everything else. So the entire consumption of your hot water (or whatever you have connected to T33) will be recorded as coming from the grid via the T33 meter.

Time that the T33 power is on is largely irrelevant since it's the amount of energy required to heat the water that counts. Whether you heat it in the afternoon or in the middle of the night won't change this, it's the same amount of energy to heat that water. How much hot water you use is the primary factor here, plus a little bit for heat loss from the storage tank. But all T33 consumption will be shown on the meter and charged at the appropriate rate.

Solar affects your Tariff 11 consumption only and works on an instantaneous net basis.

For example, suppose that at 2pm you are using 1kW and the solar is producing 3kW. The surplus 2kW goes into the grid and is recorded by the meter on a separate register (not sure what they call it in Qld, here in Tas it's Tariff 110 for export to the grid).

Now suppose that the cloud comes over and your solar output drops to 1kW just a few minutes later. And you decide to boil the kettle, raising your consumption to 3kW. You are now drawing 2kW from the grid, plus the 1kW that your solar is producing, to run the 3kW of load that you have.

This works on an instantaneous basis. You can be exporting to the grid one minute, and importing the next if load and solar conditions change.

To illustrate the point, suppose that your solar was producing a steady 1kW and that you had a 2kW load connected to a device that turns it on for 10 seconds, off for 10 seconds, on for 10, off for 10 etc and that occurs constantly. Half the time the meter would see that you were exporting 1kW to the grid (when the load is off) and the other half of the time it would see you importing 1kW (when the load is on, the other half of the load being supplied directly by solar).

So after an hour of doing this, the meter would have recorded 0.5 kWh exported to the grid and 0.5 imported from the grid. That the two figures appear to cancel each other out is irrelevant. The meter sees 0.5 kWh exported, and 0.5 kWh imported. The electricity company will pay you for 0.5 kWh at the appropriate rate (solar export) and you will pay them for 0.5 kWh at the appropriate rate (Tariff 11).

If the solar export rate (price) were the same as the Tariff 11 rate then the above would result in no actual cost. Both registers on the meter will be going up, one costing you and the other paying you, but the net cost would be zero.

But if the solar export price is less than what you pay for power consumed on Tariff 11, then the amount they pay you will be less than what you pay them, so the above will result in you spending money on electricity.

If you sell a dozen apples at $1 each then buy them back an hour later at the same price then it has cost you nothing. But if you sell them at $0.50 each, then buy them back at $1, you are spending money even though you sold 10 apples and bought 10 back. You sold them for $5 and bought them back for $10. Same with electricity - import and export are treated as two separate transactions and do not "cancel each other out".

So the easiest explanation is that you have 3 separate transactions being made.

1. Export of solar energy paid at the relevant rate.
2. Import of energy from the grid at Tariff 11 to run your appliances.
3. Import of energy from the grid at Tariff 33 for hot water (plus anything else you have connected to T33).

It is convenient that the electricity company sends you one physical invoice which includes all the above, but they could send you 3 separate ones if they really wanted to. They pay you for the solar export. You pay them for the T11 and T33 consumption.

So what's the benefit of having solar? It will reduce the amount of energy you draw from the grid at T11 to the extent that you are using electricity when the sun is shining. And you will be paid for any surplus you sell to the grid. But you will still need to buy electricity from the grid for T33 and also for whenever your T11 consumption exceeds, even momentarily, your solar system's output (eg at night or when you have higher power consumption during the day, especially if it's cloudy).
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Re: need explanation for some peace

Postby Alex Morrow » Wed Oct 30, 2013 9:41 pm

“Solar during the 3 month period has MADE 1086kWh”
Am I right in guessing that the 1086 kWh figure came from your latest bill? If it came from the bill, it’s unlikely that your solar “made” 1086 kWh; it’s more likely that you exported 1086 kWh (which at 44 cents/kWh makes $477.84 credit); your bill would show your net export, not what your system made. The meter for a net system doesn’t need to show how much your system produced since that isn’t relevant. What your system actually made can be found by reading your inverter.

Alex
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Re: need explanation for some peace

Postby Benny » Wed Nov 06, 2013 6:33 pm

Bee - try to take everything back to a daily basis - its easier to understand. The previous explanations have been spot on.
You say over 3 months (90 days) you have imported 279kWh on tariff 333, which is 3 units per day. Thats very low if its all used for hot water - only 60l of HW per day so you're being frugal there - well done.
You have used 745 kWh on tariff 11 which is 8.2 units per day. Again pretty low and as the others have explained is a combination of nighttime use and extra electricity over what your solar PV can provide during the day. If you say all you have on overnight is a fridge that should only be 1 - 1.5units. Is it 1 fridge or freezer too ? What about computer, TV, lights etc - all used when the sun isn't shining.
Your PV is about 5kW. This should give you about 20units per day, more in summer, maybe 28 and less in winter, maybe 12. Over 90 days you would get about 1800 units from the PV. You can only verify this by recording what the inverter displays as its not on your bills. So when you say "solar has made 1086kWh" this must be over winter, or its the nett exported kWh - meaning you have used directly from the PV 1800 - 1086 = 714 kWH (8 units per day). So your total use could be 8.2 + 8 = 16 units per day.
Where did the 1086 come from ?

PS - if your husband doesn't really want to understand, let it go. You're in credit on the bills so tell him to ask the questions here himself if he's really interested - you go and have a quiet wine.
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Re: need explanation for some peace

Postby Tracker » Thu Nov 07, 2013 10:46 am

BeeMee wrote:Total (IMPORT) combined with both Tariffs $293.47........(export) earnt us for that 3 months $477.84
leaving us a credit of $284.60


Very Nice..
Now you know that you are ahead, you really don't need to be frugal and you can just enjoy life..
Learn about your appliances and their power needs..
Still look at how you can run things when the sun shines, even pre-preparing an evening meal


So this 745kWh and the 279kWh is what is used at night then?

Perhaps, but not always - it depends on WHEN they activate the Off-Peak Hot water (we assume), and when you NEED that power..

our Tariff 33 goes off in the morning at 7.30am and on again at 8.30am (bet that will change in summer). And also off again at night at 5.00pm till 10.00pm.

and it depends on how you NEED that off-peak power..
It does sound like you are very frugal.. You could gain extra advantage by fitting a separate time-clock, and STOP the 33-Tariff when the sun is not shining :idea:
ie say, from 1700 to 0730.. ie.. refuse their power at night, buy heat in the day..

My thinking is that if you use so little Hotwater, then it would likely re-heat during the day, and thus you would would save that power , pre-heating the water for the AM ablutions..
Why start the day with a full load of hot water..?
..
.
Retired Engineer and keen PV experimenter - Always ready to learn and share.
2 x CMS2000 (fan cooled) GCI and SE 170W panels
1.7kW First Solar/Outback Island circuit - Peak Replacement Power
Governments won't save the world :-) They will just TAX it :-(
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Re: need explanation for some peace

Postby Smurf1976 » Thu Nov 07, 2013 6:05 pm

Tracker wrote:You could gain extra advantage by fitting a separate time-clock, and STOP the 33-Tariff when the sun is not shining

How? Is T33 not separately metered in Qld?

Eg your solar is producing 3 kW, household load apart from hot water is 0.5 kW, the hot water draws 3.6kW. Turn that on during the day and you'll be exporting 2.5 kW at the applicable FIT rate, and drawing the entire 3.6kW for the hot water from the grid charged at the appropriate rate. Solar does nothing to affect the T33 load or metering.

At least that's how it works with Tariffs 41 / 42 (24 hour heating and hot water), T61 (equivalent to T33 in Qld) and T62 (off-peak shorter hours) here in Tas. The solar affects only the light and power tariff, with no affect on the others.
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Re: need explanation for some peace

Postby BeeMee » Wed Nov 13, 2013 9:30 am

Sorry I haven't gotten back sooner, tearing the kitchen apart with renovations. Its a mess with illegal wiring that we have had to correct to 18" between securing points, instead about 8 feet falling out of the ceiling when it was removed.

Hubby has finally got it! Hooray peace reigns. He just didn't seem to get that no solar at night, taking off grid! but he does now.

To Benny... the 1086 was taken off the account and I can't remember what one off hand, just grabbed one from the file.
Total usage for hot water will change, moved our main water supply pump to that tariff, as it doesn't hinder us with the 2 "power offs" during the day. At what I pay for that per unit is a lot less than domestic. Besides having 3 pumps will take a hit on domestic, so we moved one to hopefully balance it out.
That's beyond me how you worked that out with 60l per day of hot water. But frugal yes, we rely on a tank and underground water, so if it doesn't rain soon, we will be on rainwater only. And we have lived in the bush where the only water we had fell from the sky.
Running after the sun goes down...
TV for about 3-4 hours (CRT TV, not LED or Plasma)
PC about 1 - 2 hours, mainly on when the sun comes up and off at sundown.
Fridge has a freezer.
Lights only one, in where we watch TV.

To everyone else who has commented on my post, many thanks, I have gleaned even more from all the posts and that has made other things a little clearer.
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