Solar panels: do they save money?

[Phil Pascoe]

no, agreed. I did look at a 8kWp system but according to the calculator, lifetime net benefit was only £193. I'm sure it would perform better than that, but in my case I would be better spending some of the £10k installation cost on reducing the heat loss from my property.

Yes. We've done everything realistically possible. The EPC when we moved said we could go up a level if we went over to low energy lighting - there was one lamp in the whole place that wasn't already low energy. It did however miss 6mtrs of single skin 100mm block wall between the garage and the bungalow which was actually against building regs. when it was built, it should have been cavity. It suggested we dug up solid concrete floors and fitted insulation ............. which would have justified its installation in about three centuries.

 

[Phil Pascoe]

Payments under the FiT scheme are not a simple case of subsidising the rich at the expense of the poor - it was the only way in which PVs were ever likely to be generally adopted.

The obvious way (I said this four decades ago) would have been to make their installation mandatory on all new builds and commercial buildings. For one thing installation is far cheaper at the building stage than as a retro fit. The price by now would have plummeted and their development possibly be far more advanced. Hundreds of thousands of hectares of industrial estate, shopping centre, railway and bus station roofs all of which could be covered in solar panels - no need to take farm land for them.

 

[Crazy Dave]

Many energy companies claim that they supply 100% renewable energy so why does the price go up with the wholesale gas prices?
The answer is that all electric energy is pooled together and then sold so as it's mixed the price of renewable energy goes up as well.
So in that case it's NOT 100% renewable then is it?

We're all being scammed by energy companies, as always.

 

[Ollie78]

Many energy companies claim that they supply 100% renewable energy so why does the price go up with the wholesale gas prices?
The answer is that all electric energy is pooled together and then sold so as it's mixed the price of renewable energy goes up as well.
So in that case it's NOT 100% renewable then is it?

We're all being scammed by energy companies, as always.

I argued this point with someone from an energy supplier.
I said they cannot possibly guarantee they supply renewable energy only when attached to the national grid.
I further stated that it is possibly illegal to do so, especially in relation to sales of something and consumer rights.
They could not ( or would not) understand what I was saying.

I would love to be able to have solar and maybe a bit of wind power and a huge battery just to be off the grid.

Ollie

 

[Crazy Dave]

"How does the renewable energy supply chain work?
Renewable energy is generated, added to the national grid, mixed with energy from other sources, and finally piped out to houses and businesses in the UK."

Source: Octopus Energy
Published on 15th May 2018 by: Pete Miller
Head of Customer Experience

 

[Crazy Dave]

I argued this point with someone from an energy supplier.
I said they cannot possibly guarantee they supply renewable energy only when attached to the national grid.
I further stated that it is possibly illegal to do so, especially in relation to sales of something and consumer rights.
They could not ( or would not) understand what I was saying.

I would love to be able to have solar and maybe a bit of wind power and a huge battery just to be off the grid.

Ollie

Yeah me too.

 

[hairy]

We could profitably have a wind turbine. A 3.5KW plumbed into the mains would be about £25K installed. Excess production locally limits me to 3.5 down from 5 originally. Plus an annual service plus insurance with it being within quite a long way of a road/house for when the blades fly off.
The turbine itself only costs something like £5K, or did at the time.
Instead of FIT and grid connections I wonder if there is a future in each property having its own production and storage?
Any"renewable" grid connection requires a duplication in capacity for when the wind/sun is being cheeky because demand doesn't take that cheekyness into account.
As some on this thread have said, it is perfectly possible if you know it's going to be sunny you put the washing on, because you profit from your installation. Individual decision making is possible.
A lead acid battery bank in your shed (communal?) of a size to run a washing machine, charged from your own turbine and or solar panels could be a scalable kit installed by a nationwide govt sponsored contractor. You in control of your supply in a limited way, no profit directly just savings as life goes on ever more expensively. The house remaining on grid as now, just a mains battery sourced supply for whatever you plug into it.
Not lithium of course, limited lifespan and much more expensive in a use where paying more for the weight saving is irrelevant. Lead would require perhaps more maintenance but that could be interested competent householder or a visiting techy.
Using ones shiny Tesla as a battery bank is only sensible if your wallet is deep and you shut your eyes when you watch how fast it's emptying. Such a cars lithium battery at say £10K new lasts 1000 full charge cycles. Every time the leccy company borrow some of your stored capacity you may get paid a profit on the energy cost down the cable but does it cover battery degradation?

 

[Blister]

I had a 10 panel system with a 3.5 kw battery fitted a month ago
It is a learning curve , Things like doing washing on days when the sun is shining , same with the dish washer that way you are using energy your system produces , my battery was charged to 98% by 10.30am , then the system powers the home anything else is exported into the grid , I now should not get a monthly electric bill and have worked out on my February energy exported this amount is £25 , as the sun gets higher and the days get longer this will go up , on the flip side it will also go down in winter , Overall I am happy

 

[Blister]

My panels are on the garage roof , Direct south facing
84FAF74E-6255-4395-9311-0EB692AF2478 by https://www.flickr.com/photos/150639903@N08/, on Flickr

Inverter inside the garage

52DF6E52-8620-4171-BB59-601FC70F7CAC by https://www.flickr.com/photos/150639903@N08/, on Flickr

And the battery

1E739F41-6B66-4EA1-882C-04452EA58544 by https://www.flickr.com/photos/150639903@N08/, on Flickr

All fitted in a day

 

[Sideways]

Using ones shiny Tesla as a battery bank is only sensible if your wallet is deep and you shut your eyes when you watch how fast it's emptying. Such a cars lithium battery at say £10K new lasts 1000 full charge cycles. Every time the leccy company borrow some of your stored capacity you may get paid a profit on the energy cost down the cable but does it cover battery degradation?

You are very wise to be sceptical but the battery situation is better than you describe.
The more durable type of storage battery for solar PV is lithium iron phosphate. These don't have the highest energy density like you need in your electric car, but they do last better. The major brands all guarantee their battery packs for either 6,000 or 10,000 full cycles, at the end of which they still have 80% of the initial capacity.
Using rough numbers, £10k will cover the cost of the electronics and 16kWh battery in my own planned solar install. Battery is guaranteed for 10,000 cycles, and over the guarantee, will drop from 16kWh to about 13kWh capacity. Average about 14.5kWh.
So £10k / 10,000 cycles is £1 for every 14.5kWh I put through it. Or 7p / unit to store my "free" (not really of course) solar power to use when it's needed.
In practice, I expect a few years for free after the 10yr warranty period because I won't bother replacing they cells until they are down to (say) 65% capacity.
Now the feed in tarrif is gone and the export guarantee pays only 5 to 6p per unit, there is no benefit to me letting the grid draw on my planned battery storage. They pay less than it cost me. The key to modern residential solar is: you make it, you use it.

BTW, lead acid isn't a good technology for any of this. China is full of electric scooters powered by 4,5 or 6 lead acid batteries. They are cheap and great fun, but the batteries are worn out after a couple of years commuting to work. Those really don't achieve 1,000 cycles, and by the end have nowhere near 80% capacity left.
There are other wet cell batteries with far longer than 10 year lives but bulky and not lead acid tech.

 

[Bob Chapman]

Many energy companies claim that they supply 100% renewable energy so why does the price go up with the wholesale gas prices?
The answer is that all electric energy is pooled together and then sold so as it's mixed the price of renewable energy goes up as well.
So in that case it's NOT 100% renewable then is it?

I argued this point with someone from an energy supplier.
I said they cannot possibly guarantee they supply renewable energy only when attached to the national grid.

I don't understand this. My energy company says it supplies 100% renewable energy. I take this to mean that my energy consumption (wherever and however it was generated) is replaced by an equal amount of energy generated by renewable methods. The actual electrons used by me may not be the ones generated renewably but so what - an electron is an electron. Your argument is like saying that when you withdraw money from your bank account it's not your money because it's not the same pound coins you paid in.

I'm not trying to start an argument - have I simply misunderstood something?

 

[Sideways]

No Bob. You understand it just right.
AVERAGED OVER A PERIOD OF TIME is the key.
In a flat calm in the middle of the night, renewable energy customers are dependant on nuclear, gas, etc energy like everyone else. So the grid draws on those sources. On sunny / windy days renewable generation provides the power even for those who haven't opted for 'renewable energy" so I picture it like borrowing and paying back.

 

[Blister]

Look at the National grid as a huge pot , All energy goes into the pot , Clean and dirty , Solar / wind farm / nuclear , over half the uk energy is now clean. and my little bit goes in the pot as well.

 

[Phil Pascoe]

The objection is to their using 100% renewable as a selling point when it obviously isn't - if they can advertise that when there is next to no renewable energy generated (a dead still night) some companies therefore must be 100% non renewable. Planting a few trees doesn't compensate, either, and I bet if all the supposed renewable energy sold by all companies were to be calculated it would be way more than the total generated.

 

[RobinBHM]

No Bob. You understand it just right.
AVERAGED OVER A PERIOD OF TIME is the key.
In a flat calm in the middle of the night, renewable energy customers are dependant on nuclear, gas, etc energy like everyone else. So the grid draws on those sources. On sunny / windy days renewable generation provides the power even for those who haven't opted for 'renewable energy" so I picture it like borrowing and paying back.

renewables dont work all the time -I always thought that was a major disadvantage but in fact what it really means is that there is a need for back up -for when renewables do not generate, however renewables are still beneficial for the time when they do produce -and the UK is increasing its battery storage.

 

[Blister]

My system produces power during daylight hours ,
My home uses stored power from my battery at night.

 

[hairy]

You are very wise to be sceptical but the battery situation is better than you describe.
The more durable type of storage battery for solar PV is lithium iron phosphate. These don't have the highest energy density like you need in your electric car, but they do last better. The major brands all guarantee their battery packs for either 6,000 or 10,000 full cycles, at the end of which they still have 80% of the initial capacity.
Using rough numbers, £10k will cover the cost of the electronics and 16kWh battery in my own planned solar install. Battery is guaranteed for 10,000 cycles, and over the guarantee, will drop from 16kWh to about 13kWh capacity. Average about 14.5kWh.
So £10k / 10,000 cycles is £1 for every 14.5kWh I put through it. Or 7p / unit to store my "free" (not really of course) solar power to use when it's needed.
In practice, I expect a few years for free after the 10yr warranty period because I won't bother replacing they cells until they are down to (say) 65% capacity.
Now the feed in tarrif is gone and the export guarantee pays only 5 to 6p per unit, there is no benefit to me letting the grid draw on my planned battery storage. They pay less than it cost me. The key to modern residential solar is: you make it, you use it.

BTW, lead acid isn't a good technology for any of this. China is full of electric scooters powered by 4,5 or 6 lead acid batteries. They are cheap and great fun, but the batteries are worn out after a couple of years commuting to work. Those really don't achieve 1,000 cycles, and by the end have nowhere near 80% capacity left.
There are other wet cell batteries with far longer than 10 year lives but bulky and not lead acid tech.

Lead acid is perfectly fine and well established over many years. If you discharge to a great extent they will not last as I'm sure for a commuting scooter as you suggest. For long life you aren't supposed to discharge below 80% of full so need a bigger bank than some might think. Many campers running 120Ah in their van discharge extensively and then wonder why the lifespan is so short. 120Ah may be the required capacity from use, but there won't be payload or space to fit five of them in a typical 3500kg van. Lithium works very well as a replacement because of the weight saving (assuming no cold temps to stop recharge).
If you only skim the top 20% from lead acids they will last probably better, I've never looked into the decades of experience of lead acid, but have looked into the spurious claims of lithium in EVs or storage. The current version of the lithiums in my camper suggest an expected life of 5000 cycles discharged to 50%, 2500 down to 80% used. Not a manufacturer know for telling porkies.
Will anyone fully discharge their lithiums every day? No. On average assume 50% perhaps? So the guarantee you mention for 10,000 full cycles is 20,000 days, 54 years. The tech has been in existence for less than half that so a guarantee based on accelerated lab based theory?
I would be quite happy with heavy 6v lead acids for storage at home, much more so than something guaranteed for 54 years

 

[hairy]

I wasn't miles off, since I remember the Tesla 1000 cycles and £10000 replacement cost figures I mentioned from a Tesla owner. And even then young Elon says should not will.

 

[Ollie78]

renewables dont work all the time -I always thought that was a major disadvantage but in fact what it really means is that there is a need for back up -for when renewables do not generate, however renewables are still beneficial for the time when they do produce -and the UK is increasing its battery storage.

A while ago a bloke was lurking about by my workshop which is in some scruffy farm buildings along with several other units.
He was looking for the landlord. I asked him why and he said he was looking for a site to house a giant battery for the local grid.

Turns out our site is right next to the transformer for the village and would be a perfect location. I have not seen anyone do anything yet but it shows they must be on the case with local battery stations.
Interestingly he said it was more for the purpose of reducing usage spikes than anything else.

Ollie

 

[Phil Pascoe]

The obvious way of reducing spikes is to alter the cost per kilowatt hour............ which I assume is the ultimate purpose of smart meters.