Circular reasoning (Rolfe's solar energy system)

My planned system is to charge my house battery and then the remained into the MG4, all while running the house, nothing for the grid, they can generate their own electricity ..... all the stuff I generate is for my use ...... At the moment I have two spare MG4's as well, so I can store any excess in them as well, so around 175kwh of capacity ...... should be enough for a few rainy days ;) :cool:

T1 Terry
Why? You can sell to the grid for 15p and buy off peak for 5p, why not?
 
He's in Australia. Australian export tariffs are derisory.

Mind you, before I had an export tariff at all I still had to let a lot go to the grid. The MG4 was sitting there burping and the sun was still shining. One evening I went out joyriding just to use up enough so that I didn't have to let the following day's sunshine fo to waste!
 
Why? You can sell to the grid for 15p and buy off peak for 5p, why not?
Over here, sell it to the grid, if they want it at that particular period during the day, for between 2c and 5 cents, which is the same period as cheap EV charging is available, at around the same price .....
Then 10% GST applies going into the grid and back out of the grid, then the charge for just having the power connected to the house, a bit over $1 day per meter in some cases, off peak hot water has its own meter as does any other off peak power from storage heating and cheap EV charging, ... well as the meter that they pay you for the export to the grid power .......the household supply meter has time of day pricing ..... and all of that has another 10% GST thrown on top.
They do now have back to base meters that save them paying a meter reader, that can differentiate between off peak hot water and house load and sometimes back to grid supply ..... but you have no idea if they have decided they don't need you solar feed in today and switch off the solar being accepted ..... or if they actually did take the power but decided they weren't going to pay you ..... or there was a "Glitch" in the system ....... unless you have your own meter as well, you just don't know .....

It was one of those "back to base" meters "we suspect" started the power box fire that burnt the house and motorhome to the ground .... but it could have been a poor connection when the meter was installed .... who knows, but the fire pattern leads back to the powerbox, but no one is game to take on the state power network in a court battle, even the insurance company ...... so, there will be no grid power connected to our new house .... if we actually rebuild that is ......

T1 Terry
 
Over here, sell it to the grid, if they want it at that particular period during the day, for between 2c and 5 cents, which is the same period as cheap EV charging is available, at around the same price .....
Then 10% GST applies going into the grid and back out of the grid, then the charge for just having the power connected to the house, a bit over $1 day per meter in some cases, off peak hot water has its own meter as does any other off peak power from storage heating and cheap EV charging, ... well as the meter that they pay you for the export to the grid power .......the household supply meter has time of day pricing ..... and all of that has another 10% GST thrown on top.
They do now have back to base meters that save them paying a meter reader, that can differentiate between off peak hot water and house load and sometimes back to grid supply ..... but you have no idea if they have decided they don't need you solar feed in today and switch off the solar being accepted ..... or if they actually did take the power but decided they weren't going to pay you ..... or there was a "Glitch" in the system ....... unless you have your own meter as well, you just don't know .....

It was one of those "back to base" meters "we suspect" started the power box fire that burnt the house and motorhome to the ground .... but it could have been a poor connection when the meter was installed .... who knows, but the fire pattern leads back to the powerbox, but no one is game to take on the state power network in a court battle, even the insurance company ...... so, there will be no grid power connected to our new house .... if we actually rebuild that is ......

T1 Terry
Apologies, I hadnt realised you were in Australia.
 
I tried again yesterday to harvest the clipped excess, but made a mistake and in the end the home battery was at 65% at the beginning of the day. I did have an opportunity to export some more in the early morning but I was half asleep and decided just to let it run. In the event the afternoon turned out to be very sunny and the battery got to 100% about an hour before clipping stopped and there was nothing I could do about it.

I'm learning. First not to make that silly mistake, and second, to make sure the battery is down to about 40% (if not below) if the forecast is looking sunny. Tomorrow looks like another day where it's worth a try, even if only to try to get it right this time.
 
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It's quite interesting how this is really a case of mony a mickle maks a muckle. Get it wrong once and you're only down buttons. But get it right and keep on getting it right day after day, and by the end of the month you're quids in.

In other related news, my Octopus bill to 17th April credited me with £111.27 overall.
 
A while back, people were claiming on the forums they hadn't had to pay for electricity since they put the solar on back in the early days of solar adoption over here ...... but they were still on the 60 cents per kw/h feed in tariff ...... as soon as anything in the system is changed, the power mobs drop the feed in tariff to a lesser amount for a fixed period .... it got that bad that at some stages there was talk of actually charging to dump solar into the grid ....... you don't hear many of those boasts these days, just screams about the bills and the power company stealing the power out of their house battery, and paying them the pitifully low price, resulting in them being forced into buying power at the peak rate of around 44c per kwh between 4pm and 9pm in South Australia.

The claim is they use the house battery power when an imminent system overload occurs and that is the trade off for the solar battery rebate ........ but it only seems to happen when the network power price is high ..... or would be high if they couldn't get it cheaper else where :rolleyes:

T1 Terry
 
In other related news, my Octopus bill to 17th April credited me with £111.27 overall.
Interesting numbers, for the same period our 4kW array on FiT with no battery generated £115 income, and we paid Octopus £62. it was made up of 498 kWh generated, of which 180 was consumed. We consumed 444 kWh in total (164 into the car) so we imported 264.
 
Mine was made up of £145.57 in export credit and £34.30 in electricity consumed. But I just realised there's a separate amount for electricity before 1st April which needs to be added in so it's not as good as I claimed. The correct net profit is £81.21.

I made a different (but related) error last night which resulted in the Eddi taking power from the battery instead of the grid to heat the water in the early morning. Result, I lost 20p (difference between off-peak grid price and what I could have exported that 2.5 kwh for), and woke up to a battery at 22%, which was somewhat lower than I had been shooting for. However, although there's a fair bit of cloud around there are blue-sky patches and the battery has already grabbed a little. How much I get obviously depends on the ratio between time when the sun is full out and time when it's obscured by cloud, but I expect the battery will pick up enough for there to be no problem lasting the evening. Actually, 22% would probably be enough if I didn't put on a roast or something, even if deep gloom suddenly descended, which it's not going to.
 
A while back, people were claiming on the forums they hadn't had to pay for electricity since they put the solar on back in the early days of solar adoption over here ...... but they were still on the 60 cents per kw/h feed in tariff ...... as soon as anything in the system is changed, the power mobs drop the feed in tariff to a lesser amount for a fixed period .... it got that bad that at some stages there was talk of actually charging to dump solar into the grid ....... you don't hear many of those boasts these days, just screams about the bills and the power company stealing the power out of their house battery, and paying them the pitifully low price, resulting in them being forced into buying power at the peak rate of around 44c per kwh between 4pm and 9pm in South Australia.

The claim is they use the house battery power when an imminent system overload occurs and that is the trade off for the solar battery rebate ........ but it only seems to happen when the network power price is high ..... or would be high if they couldn't get it cheaper else where :rolleyes:

T1 Terry

That sounds pretty mean. I expect to be in decent profit over the year as a whole, buying at 7p overnight and selling back all surplus (solar plus whatever I still have in the battery when the peak tariff ends) for 15p.

I can see your power company is in a very different position, with more solar than it knows what to do with in the middle of the day. We never seem to be in that position, although Octopus will occasionally incentivise people to use more power around midday on sunny days.

I also don't like the idea that you don't have control over what's going on. During the winter Octopus did have something going to incentivise people to feed back power from a home battery to the grid during heavy load periods, but it was entirely voluntary (I don't think there's any way they can take control of my inverter) and there was a small financial reward.

There needs to be more investment in infrastructure to harvest all that solar you have, and make use of it. And not screw the microgenerators over.
 
Hmm....... the electrical retailers in South Australia risking people thinking they are mean or making a profit for the executive's bonus package .... which way would they choose :unsure:

The SA Power network makes good money selling renewable power to the adjoining states, but there is only so much they can move over the DC interconnector to NSW and Victoria, they are working on improving that so we stop having excess supply in the grid, as are the big solar farms adding their own battery storage.
At the moment, if the supply doesn't exceed the amount they are selling interstate, then the wholesale price goes up to cover the lost earnings ..... if they have to start any of the back up generator plants or buy power back from either of the states (heaven forbid) the price goes up big time ..... and that would cut into profits .... :oops::eek: ....... an absolute last resort, power cuts would be the more likely result of such an event, so using the energy stored in the suckers house batteries would be seen as avoiding power rationing ........ al for the greater good you see :rolleyes:

T1 Terry
 
Hmm....... the electrical retailers in South Australia risking people thinking they are mean or making a profit for the executive's bonus package .... which way would they choose :unsure:

The SA Power network makes good money selling renewable power to the adjoining states, but there is only so much they can move over the DC interconnector to NSW and Victoria, they are working on improving that so we stop having excess supply in the grid, as are the big solar farms adding their own battery storage.
At the moment, if the supply doesn't exceed the amount they are selling interstate, then the wholesale price goes up to cover the lost earnings ..... if they have to start any of the back up generator plants or buy power back from either of the states (heaven forbid) the price goes up big time ..... and that would cut into profits .... :oops::eek: ....... an absolute last resort, power cuts would be the more likely result of such an event, so using the energy stored in the suckers house batteries would be seen as avoiding power rationing ........ al for the greater good you see :rolleyes:

T1 Terry
I can see why you want to off grid!!!

Can you have a separate battery isolated from the grid for your own personal use?
One of those MG4 batteries would be fine.
 
Of course, on the day when my mistake meant that the battery was at too high a SOC overnight, there was more sun than forecast and I didn't manage to capture it all. Then on the day when my mistake meant that the battery was lower than I had planned, there is less sun than forecast! Nevertheless the battery has already clawed its way up to 44% (3 pm) so there isn't anything to worry about.

I note that on the perfect day (10th April as it happens), The battery put on 62% by grabbing what would have been clipped. It may be that that's a maximum. I had thought that closer to the solstice it might be better, but I hadn't realised just how much effect temperature has. Although the sun will be higher, and for longer, in the summer, it will also be warmer.

This suggests that having the battery at 35% should really cover anything. It will be enough to grab a perfect day's solar (or we'll see how that goes in June anyway), but still be enough to live on if there isn't any clipping at all during the day.

The thing is, it's a fiddle to keep changing the inverter settings. I've got one setting for winter where it stays, because obviously nothing is going to be clipping in January. It would be nice to have an equally simple summer setting where there was enough space in the battery to whatever came up, but still enough to last the evening if nothing came up. That actually might be possible, and I'm going to experiment more this week of rather mixed weather and see what happens. I think that if I can get it right, export the battery down to 35% overnight, then hold it there till early evening, poised to take what comes, it should work. If it does, it would save a lot of fiddling, changing the inverter from one configuration to the other in the evening depending on the weather forecast.

The issue isn't so much days when there's no clipping, so I enter the evening on 35%. That's enough for most purposes. It's days when the solar is so poor during the day that it won't cover the house load (either when, say, I boil the kettle or run the vacuum cleaner, or even the base load if the weather is really horrible), and in this configuration the battery isn't available so peak-rate mains power gets taken. I'm thinking that if I wake up and it's that sort of a day, I could just disable the export settings and let the battery charge from the solar and discharge to run the house as it likes. I wouldn't have to reconfigure the whole caboodle.

I suppose the main issue, like now when I want a coffee and the solar is happily supporting the house but not providing the 3.5 kw needed to boil the kettle on top of that, that I need to disable the export setting while the kettle boils. Maybe too much hassle. I suppose I'll find a modus vivendi by experimentation. Right now I'm thinking, I could just disable the export setting and forget all about it, letting the battery have the solar from now instead of exporting it. It will get exported anyway, from the battery, later. But then, losses...
 
I can see why you want to off grid!!!

Can you have a separate battery isolated from the grid for your own personal use?
One of those MG4 batteries would be fine.

Here, the issue is winter. Ask @QLeo about that. You can store enough solar in summer to keep you going, powering the night from yesterday's solar, and over the week you're fine. But in winter when day after day there's nowhere near enough, how do you store excess summer solar and use it then? How many MG4 batteries would you need?

QLeo has a wind turbine and a diesel generator, though I believe he's driving Goth Leo to the nearest charger and bringing back grid-derived electricity that way to run the house from VtL, rather than burn diesel. Storing excess summer solar for winter isn't yet practical.

However, I have no idea what it's like in winter in Australia. Is there still enough to run the house load, spread out over a week or so? You won't get enough to charge a car though, surely.
 
Welcome to all the fun of solar, @Rolfe

Sounds like you need to extend, rather than get out of your original loop with a step 9...
Step 9. Need more batteries
 
I don't think so. I want an EPS, and I'd still like to find out if it's possible to feed power from the car battery into the home battery, but other than that it will do me. At the moment I'm trying to find the optimum configuration for the inverter so as to fiddle with it as little as possible. I'm sorted for the winter months, works a treat. It would work like that all year, but I'm finding it fun figuring out how to harvest the solar that would otherwise be clipped.

Once I've got a set-up worked out so that I'm not making silly mistakes, I'll let it run for a bit and see how it goes. It wasn't much trouble when I boiled the kettle simply to disable the export before I switched the kettle on, and enable it again once it had boiled. On a really sunny day I wouldn't have needed to bother. Even now, the solar has gone back up to 3.5 kw, so I wouldn't have had to bother. Once it gets time to start cooking in the evening I'll probably just disable it entirely.

Of course, once I have the set-up finalised, I might decide it's easy enough to change back to the winter settings if the forecast suggests there won't be any clipping to harvest, and back again when it's sunnier.
 
I don't think so. I want an EPS, and I'd still like to find out if it's possible to feed power from the car battery into the home battery, but other than that it will do me. At the moment I'm trying to find the optimum configuration for the inverter so as to fiddle with it as little as possible. I'm sorted for the winter months, works a treat. It would work like that all year, but I'm finding it fun figuring out how to harvest the solar that would otherwise be clipped.

Once I've got a set-up worked out so that I'm not making silly mistakes, I'll let it run for a bit and see how it goes. It wasn't much trouble when I boiled the kettle simply to disable the export before I switched the kettle on, and enable it again once it had boiled. On a really sunny day I wouldn't have needed to bother. Even now, the solar has gone back up to 3.5 kw, so I wouldn't have had to bother. Once it gets time to start cooking in the evening I'll probably just disable it entirely.

Of course, once I have the set-up finalised, I might decide it's easy enough to change back to the winter settings if the forecast suggests there won't be any clipping to harvest, and back again when it's sunnier.
Enjoying the continuing tale with the panels etc. I’m still setting out my four “camping “ panels most days to monitor my sun capture - currently facing a wee hole in the clouds so only picking up 10 to 15 Watts ! But it all adds up. It was 120 Watts at midday.
Whilst enjoying a fine cup of coffee as I sit in the garden beside the power station battery, I’ve ordered a challenge to be delivered to my Granddaughter in San Diego.
I’ve sent her a Solar x v2 sun tracking power kit. It was her 14th birthday yesterday and she’s into everything- softball, trumpet playing, fence building, climbing, science , cycling etc so I’ll challenge her to charge her phone 🤣🤣
 
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