Taking the plunge into solar ?

[ExMX5owner]

For the house not the car before you start..

Any of my new friends been up this creek ?...

 

[Synclare]

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[ExMX5owner]

Like all things in life it has mercenary motives. From what other Aussies have experienced the government were encouraging people to produce their own energy, clearly having an abundance of the bright stuff As the uptake was quite good and everyone was getting good 'pay back' deals selling their surplus energy to what we call the 'national grid', things changed. The government twigged they had shot themselves in the foot. Having a vested interest in their own power stations, coupled with folk selling their home produced energy back to the 'national grid' the power stations were not flogging as much energy as usual. The result was a marked reduction in how much energy the power stations allowed to be sent back down the grid, thus pay back deals were no longer as attractive. So all this 'save the planet' stuff is a load of nonsense as it all comes down to monetary income to those with a vested interest i.e the government as per usual.

Here in u.k the government were pushing for the use of diesel for cars years ago, as more people switched to it up went the price. Same with LPG.

Now with electric vehicles, you have to have a smart meter to monitor your usage of electricity, guess what, they will eventually start taxing you on it yet again to replace their lost income from petrol sales.

Anyway, back to solar, you would I think need a storage device, aka a battery, to be able to use this energy at times it is not being produced. I guess they don't come cheap.

I like your thinking, and also considered these factors. I,m going for a 13kw system, battery compatible, none of this micro inverter crap that;s being punted as the next great thing. Storage devices are coming down in price, primarily as result of E and hybrid cars..We have cathedral ceilings though the section of house where I will put the panels, they should offer some protection from the Aussie sun with the airspace, and deaden the decibels when it rains..We rely on aircons just to keep things tolerable for fair portion of the year, It is fortunate that the house is orientated to take advantage of our 16S latitude..But yeah I agree with what you have typed..Sooner or later 1 person is going to be supporting all the infrastructure... .

It's going to cost around 13k, but I figure the return on investment is favorable given that most of it will still be in service long after I am pushing up daisies..

Putting it all in to perspective, a Z3 of any flavor worth buying would cost more than that here..

 

[Jasn]

The cost-effectiveness depends entirely on how much power you use and when. We have a 5.4kW system which, on a sunny day, covers most of our daytime use and also exports a fair bit to the grid. It mostly covers our ducted air-con during the hottest part of the day. We try to do laundry, run our pond pump and filter and things like that during the day to use solar and try to avoid anything like that during the night to minimise what we import. That works for us, but some people don't have the flexibility to align their usage with their solar generation. Our system has just paid for after four years. We had it installed when we were doing a house extension and it also helped us get the extension over the energy-efficiency requirements.

At present, home batteries are going up in price. A few years ago, we could get a Tesla powerwall for $12K (and get a grant for some of that from the Qld Government), but today it would cost about $16K and no grant. It doesn't make sense financially and I think it might be some years before they become cheap enough. I sometimes think about getting a small battery (say 2 or 4kWh) to cover most of our overnight standby use, but the payback is still marginal. I should have bought a big battery when they were cheaper and grants were available.

Our system has an optimiser for each panel. I don't think they are micro-inverters, but they achieve a similar thing by allowing the system to get the most out of each panel. Without some similar arrangement, then your whole system only runs at the output level of the worst-performing panel. So if you have any shading, all the panels will only output the same as the shaded panels. This also affects what you get early in the morning and late in the afternoon, even with a north-facing roof.

13kW is a huge system for a house. You'll probably be putting a fair bit back into the grid, but that's not lucrative the way it used to be. In the early days of solar, people were getting cheques because they were getting paid so much for what they fed in, but now you are likely to only get 5 to 15 cents per kWh and with some providers that will be capped. It's difficult to say how things will change over time though. The generators have talked about capping how much power you can feed back in, though I think that would be politically difficult to implement. If you end up with an electric car, you could charge it with the excess if your car is home during the day.

Anyway, this is just food for thought. The economics of it really depend on how your household uses power.

Jasn

 

[ExMX5owner]

The cost-effectiveness depends entirely on how much power you use and when. We have a 5.4kW system which, on a sunny day, covers most of our daytime use and also exports a fair bit to the grid. It mostly covers our ducted air-con during the hottest part of the day. We try to do laundry, run our pond pump and filter and things like that during the day to use solar and try to avoid anything like that during the night to minimise what we import. That works for us, but some people don't have the flexibility to align their usage with their solar generation. Our system has just paid for after four years. We had it installed when we were doing a house extension and it also helped us get the extension over the energy-efficiency requirements.

At present, home batteries are going up in price. A few years ago, we could get a Tesla powerwall for $12K (and get a grant for some of that from the Qld Government), but today it would cost about $16K and no grant. It doesn't make sense financially and I think it might be some years before they become cheap enough. I sometimes think about getting a small battery (say 2 or 4kWh) to cover most of our overnight standby use, but the payback is still marginal. I should have bought a big battery when they were cheaper and grants were available.

Our system has an optimiser for each panel. I don't think they are micro-inverters, but they achieve a similar thing by allowing the system to get the most out of each panel. Without some similar arrangement, then your whole system only runs at the output level of the worst-performing panel. So if you have any shading, all the panels will only output the same as the shaded panels. This also affects what you get early in the morning and late in the afternoon, even with a north-facing roof.

13kW is a huge system for a house. You'll probably be putting a fair bit back into the grid, but that's not lucrative the way it used to be. In the early days of solar, people were getting cheques because they were getting paid so much for what they fed in, but now you are likely to only get 5 to 15 cents per kWh and with some providers that will be capped. It's difficult to say how things will change over time though. The generators have talked about capping how much power you can feed back in, though I think that would be politically difficult to implement. If you end up with an electric car, you could charge it with the excess if your car is home during the day.

Anyway, this is just food for thought. The economics of it really depend on how your household uses power.

Jasn

Thanks Jasn, for your input. Our decision to go for such a huge array, was largely to cover all of the house that exposed beams and subsequently no insulation worth talking about. It also gets incredibly noisy in the FNQ tropical rains. i dont think the provider here is doing enough to maintain infrastructure either, bandaid on a gaping wound scenario. We would like to hammer the crap out of our aircons during the hot months during times of peak generation, block and tile house holds the cold quite well. The pool also can have its pump managed to suit. But yes 13kw is a bit of an overkill, but 1/3 of the panels will be facing south, as the house is not quite facing north and benefits for this is that we can generate 5kw for a greater portion of the day, which is the maximum draw from each of the inverters, either for use, or the maximum feed back to grid.. It,s done my head in really, there is so much disinformation out there..Battery prices will come down, I'm convinced of that, but it may not be soon.. Merry xmas my friend..

 

[Synclare]

.

 

[Pingu]

I have solar and will be getting a battery when they become available (date has slipped from June 2022 to Jan 2023).

The solar was fitted on 15 May 2022. Our payments were as follows...

07/02/22	149.15
27/03/22	82.32
05/05/22	84.96
07/05/22	1.59
07/05/22	8.54
23/05/22	46.29
30/05/22	10.00
27/06/22	43.52
06/07/22	21.04 exported to grid

27/07/22	47.52
07/08/22	30.95 exported to grid
27/08/22	54.89
13/09/22	51.99
13/09/22	83.00 exported to grid
19/09/22	4.92 exported to grid
27/09/22	60.52
27/09/22	8.05 exported to grid
30/09/22	6.79
27/10/22	70.02

27/10/22	29.96 exported to grid
27/11/22	95.72
27/11/22	7.78 exported to grid

 

[Pingu]

The only change that we have made is to buy an 830W kettle. It takes longer to boil, but can be done for free. The 2KW kettle draws too much current for all but the brightest days at noon. Most days, when the sun shines we can have free boiling water for out tea and coffee.

As said, above, the key is to have some way to store the energy (I wish I still had the hot water tank and immersion heater). I was paid 7ppkWh for excess energy, but paid them 33ppkWh when I drew from the grid. It's now 15/41 with a nightime rate of 15.

My aim is to generate during the day and top the battery up at night for 7.5p per kWh. In UK, you can get a cheaper night rate if you have an electric car or an approved storage battery.

I have a friend in Spain, and he uses a load of lead-acid batteries and runs his house off 12v with 240v invertors. Your TV is 12vDC if you bypass the 240v stuff in the back .

 

[ExMX5owner]

@Jasn .Yes we opted for that sort of system as well, we get bats here, big ones. that after a night out on the mango's can make an orribly sh%tty mess.

 

[OhioZ4]

Alot of people around me are putting solar panels on their roof . I was told it will take about 10 to 15 years to get your money back in return , not sure if thats quite worth it to me . I also wonder how much more its going to cost when it comes time for the roof to be replaced , I cant imagine its going to be cheap. I would however ,if building new construction , had some extra land available , install some away from the home , probably be alot easier for maintenance and installation .

 

[ExMX5owner]

Alot of people around me are putting solar panels on their roof . I was told it will take about 10 to 15 years to get your money back in return , not sure if thats quite worth it to me . I also wonder how much more its going to cost when it comes time for the roof to be replaced , I cant imagine its going to be cheap. I would however ,if building new construction , had some extra land available , install some away from the home , probably be alot easier for maintenance and installation .

Yes we are getting the roof refurbished prior to installation, I did consider that.. Return on investment is between 6 & 8 years, variables are feed in value and buy out value, other values have already been determined, and are largely predictable. none the less this still works out at around 25% per year ROI, better than money in the bank I would say. Possibly the most useful aspect is that we would no longer be that concerned about wasting energy during the day, a bit of added value there. We will see...

 

[ExMX5owner]

I have solar and will be getting a battery when they become available (date has slipped from June 2022 to Jan 2023).

The solar was fitted on 15 May 2022. Our payments were as follows...

07/02/22	149.15
27/03/22	82.32
05/05/22	84.96
07/05/22	1.59
07/05/22	8.54
23/05/22	46.29
30/05/22	10.00
27/06/22	43.52
06/07/22	21.04 exported to grid

27/07/22	47.52
07/08/22	30.95 exported to grid
27/08/22	54.89
13/09/22	51.99
13/09/22	83.00 exported to grid
19/09/22	4.92 exported to grid
27/09/22	60.52
27/09/22	8.05 exported to grid
30/09/22	6.79
27/10/22	70.02

27/10/22	29.96 exported to grid
27/11/22	95.72
27/11/22	7.78 exported to grid

I'm trying to understand these , I assume most energy is consumed by heating ?..

 

[Jasn]

I hadn't realised the output can be dragged down to the level of the worst performing panel.

Also I guess a system to tilt the panels as the sun traverses across the sky would produce optimum results but be incredibly expensive.

Musk apparantly bought the battery plant to keep control of his manufacturing costs, would that also work to keep battery systems for solar use artificially high by controlling the market?

I think most systems from good installers are set up to make sure you get the best out of each panel. Cheaper systems may not and ones installed years ago don’t.

I think Covid, war in Ukraine, inflation in many countries, poor exchange rate in Australia and various other things are all keeping batteries expensive. They will get cheaper when the technology becomes more mature but I think that is a way off. Tesla might have a bit of a premium due to the brand, though I think Musk is doing some damage to the brand at the moment.
Jasn

 

[Jasn]

Yes we are getting the roof refurbished prior to installation, I did consider that.. Return on investment is between 6 & 8 years, variables are feed in value and buy out value, other values have already been determined, and are largely predictable. none the less this still works out at around 25% per year ROI, better than money in the bank I would say. Possibly the most useful aspect is that we would no longer be that concerned about wasting energy during the day, a bit of added value there. We will see...

Our payback was 4 years. everything Is ‘profit’ from now on. We use our air con whenever we feel like it when it is hot - we don’t bother to worry about whether it’s worth it since it doesn’t cost much to run anymore.

I figured the panels might help the house stay a little cooler but I think it’s so minor you’d never know.
Jasn

 

[Pingu]

I'm trying to understand these , I assume most energy is consumed by heating ?..

No, the heating is by gas.

The reduction is due to the solar reducing the need to draw from the grid. The excess is excess.

Our Smart Meter was only installed in May, so I only have the figures from June, but here's our figures...

Month	Imported from Grid	Exported to Grid
June	145	233
July	153	367
August	173	404
September	191	238
October	222	190
November	255	42

Here's what the draw from the grid looked like on 06 September 2022...

Here's what the the export to the grid looked like...

The house uses what is generated by the panels first, then exports the excess. Note how the draw drops to zero when the sun is out, and there is still excess to sell to the grid after we've taken all we need.

The upblip in draw and corresponding downblip in export around 1230 was due to either lack of solar, or the use of a high current device (such as a normal kettle, or a toaster, or both at the same time). Our solar is rated for 4KW max output, but this is theoretical. The highest that I have seen is about 3.1kW (during a heatwave at 1300 [our solar midday in the summer]), so any draw larger than that has to come from the grid. This is why I've just boiled the water for a cup of tea using an 830W kettle. The Smart Meter below shows that even on Xmas Day, the solar is generating...

 

[ExMX5owner]

No, the heating is by gas.

The reduction is due to the solar reducing the need to draw from the grid. The excess is excess.

Our Smart Meter was only installed in May, so I only have the figures from June, but here's our figures...

Month	Imported from Grid	Exported to Grid
June	145	233
July	153	367
August	173	404
September	191	238
October	222	190
November	255	42

Here's what the draw from the grid looked like on 06 September 2022...

Here's what the the export to the grid looked like...

The house uses what is generated by the panels first, then exports the excess. Note how the draw drops to zero when the sun is out, and there is still excess to sell to the grid after we've taken all we need.

The upblip in draw and corresponding downblip in export around 1230 was due to either lack of solar, or the use of a high current device (such as a normal kettle, or a toaster, or both at the same time). Our solar is rated for 4KW max output, but this is theoretical. The highest that I have seen is about 3.1kW (during a heatwave at 1300 [our solar midday in the summer]), so any draw larger than that has to come from the grid. This is why I've just boiled the water for a cup of tea using an 830W kettle. The Smart Meter below shows that even on Xmas Day, the solar is generating...

Ah OK, I got it, Our maximum allowed export to grid is 5 kw, this will be the max output of just one of the inverters, It is my hope to be able to export close to 5 to the grid for most of the day, It should be close with over 13 to draw from on the best days, cloudy days however Its likely that there would be no export at all, and some draw. So yes battery storage would smooth out the bumps, and the bigger the storage is the bigger the bump that can be smoothed.. We use solar hot water and the Electric backup hardly ever kicks in. We have considered gas for cooking and instant hot water for coffee and the like, despite for most of the year it being possible to cook a roast in the mailbox but the kitchen is central in the house and implementation not easy. However its not ruled out at this stage. I guess the long term target is to be "stand alone".. We can and have used outdoor gas kitchen to cook on in outages that have been lengthy or been entertaining guests, It has the added benefit of not heating up the house too much, and paper plates don,t need to be washed..

 

[Pingu]

In the UK, the max into and out of the grid is 16A, or 3.8KW. Any more than that and you need a special certificate and need to upgrade to equipment that is capable of carrying the extra load. This usually means converting to three-phase.

If you want to run your system as efficiently as possible, you need to use a battery and smooth out your usage as much as possible over a 24 hour period.

You need to know the peak demand in A or kW, and your system needs to be able to deliver to that. Tesla2 can deliver 5A/1.2kW continuous or 7A/1.7kW peak. I can't find the flowrates for the Tesla3.

You need to know how many kWh's of energy you use, and you need a battery that can hold a day's needs. Bear in mind that batteries need to be managed and should be constantly monitored. A Tesla controller will do everything for you, but the quoted rating will be from 100% to 0%. Neither conditions are accurate, as the battery should run between 80% full to 20% full to maintain maximum life. A 14KWh battery is really a 10kWh battery in the real world, although they quote 13.5kWh. A Tesla3 has double the capacity.

You need to be able to produce enough power to fill the battery (whilst simultaneously consuming).


If you are running on solar only, you need to manage your usage for when the sun is shining. If the sun ain't shining, you are paying for grid power.

You need to try to move as much stuff to the time when the sun shines. Australia is a perfect country for solar, as air-con is a heavy consumer and it's needed during daylight hours. If you have any spare solar capacity, you should move the time you use the washing machine or dish washer to take advatage of the excess. It costs more to use grid power than they will pay you for excess. We have cheap night-time rates that are the same price as excess rates, so we still run our washing machine and dryer at night.

 

[Idleness]

We had our solar installed last January we have only got 4.3kW of solar with a 5.8kWh battery. Our usage means that during the summer we were averaging about 12kWh from the grid every month as the battery is enough to tide us over from sunset to sunrise. We also managed an average export of about 375kWh a month on top of our use.
The thing that has made it all work for us is that we are on an agile tarriff which changes every half hour so as an example last night for one period we were paid 1.81p a unit to use electricity and the rate stayed below 10p all night, meaning even with no sun we could charge the battery almost for free. It doesn't happen every night but is fun when it does.
Estimated payback is 6.5 years.
Below is our import / export from the last 12 months

 

[Andybpowell]

I hadn't realised the output can be dragged down to the level of the worst performing panel.

Also I guess a system to tilt the panels as the sun traverses across the sky would produce optimum results but be incredibly expensive.

Musk apparantly bought the battery plant to keep control of his manufacturing costs, would that also work to keep battery systems for solar use artificially high by controlling the market?

I've considered this myself and so have looked into this issue from what I can see this is only the case where the panels are run in series to reduce the cabling cost so running them in parallel or in a mixed parallel/serial array where only panels that will be shaded at the same time are in series with each other should reduce the losses and minimise cabling cost also installing Schottky Bypass diodes on the array where possible would all help alleviate these issues and improve efficiency

 

[Idleness]

As you say in series, panel shading can be a problem
The top left and bottom right panels on my array in winter end up in shade at the same time, so in order to negate the problem my panels are paired in series bottom right three with top left three and top right with bottom left, this ensures that one string of six is at full output instead of losing both to the shade.
Problem with wiring in parallel is that the current goes up compared to series so you need to use much thicker cable.
6 panels in series voltage 204V current 9A is fine on 4mm cable
6 panels in parallel voltage 34V current 54A so you would need at least 10mm cable.
Even 6 in series/parallel voltage 102V current 27A so you would need at least 6mm cable as although 27A is just within spec for 4mm cable the volt drop would waste a lot of the power.