Will just posted an excellent video, check it out.

[upnorthandpersonal]

The only ROI differential is the cost of the energy supply, because the output of each rig will be the same

There is more to it. The cost of the energy forms a barrier to entry - mining profit might or might not be there, but you do definitely know your energy cost will be a given when on grid. Having excess power that you can use to e.g. mine crypto is a business opportunity that comes from having excess power to begin with (let's call it 'free' but you know what I mean). This 'free' energy is where you can get creative: would you start a mining operation, maybe even a try out with older hardware, if you didn't have this 'free' excess energy? Same with other opportunities: maybe drying fruit, meat and mushrooms (energy intensive) for own use or sale? Canning food? Something else creative that offsets other costs? This is an indirect ROI, same as e.g. consulting opportunities from the experience building a system like that, or indeed, becoming a YouTuber in the field. These opportunities are a return on the investment (money and time) which in my opinion should be calculated in.

 

[wattmatters]

There is more to it. The cost of the energy forms a barrier to entry - mining profit might or might not be there, but you do definitely know your energy cost will be a given when on grid. Having excess power that you can use to e.g. mine crypto is a business opportunity that comes from having excess power to begin with

Excess capacity is not free. If your capacity utilisation goes up because you consume more energy it just means the per kWh cost of the energy you are using has been lowered a little. All that does is increase the operating energy cost differential with the grid.

If you have a bucket load of excess unused capacity, then you have more than likely over capitalised to begin with. The marginal cost of the extra energy is never "free".

Contrast that with a wholesale grid energy price plan in some places where there are times you can be paid to consume energy from the grid...

 

[DerpsyDoodler]

You can claim ROI on mining bitcoin but you can't assign that ROI to the off-grid solar PV.

Say my neighbour and I each have identical bitcoin mining rigs. I decide to put in solar PV/battery system to power mine off grid while my neighbour leaves theirs powered by the grid.

The only ROI differential is the cost of the energy supply, because the output of each rig will be the same (on average over time).

Based on that example, you are right, but your PV is a direct result of wanting to power your miner.

Now let's say I install a pv system and its working so well i'm producing excess. One way to use that excess is to dump load it to an array of bitcoin miners. I'm not in that business and would not have done it had I not had the opportunity of excess power. In this case bitcoin is a direct result of pv not a cause of it. I would definitely calculate it as part of the ROI.
This is a direct relation of cause and effect.

This response was because I was hung up on red herrings. It makes no difference one way or the other. The bottom line is your investment is X. Your return is Y.

If you build out a solar power plant, your investment is X. Anything that you can do with that power to generate income (regardless) is in scope as ROI or Y. You can wait for 15 years to sell your power at grid rates or you can do something with that power that increases its value more quickly. Turning it into bit coin is one way to do it (assuming it would be a profitable venture).

 

[DerpsyDoodler]

Idk… if I run a business and sell widgets, lest say I make 10K a week… that makes the ROI on PV a few weeks…
Certainly, Bitcoin will produce funds from the used power, but I wouldn’t consider it part of the ROI, especially since it also raises the power consumption…

I guess, if you ARE Bitcoin mining, and you have a set power bill, the additional PV ROI could be calculated that way, but NOT the Bitcoin profit itself…

Ok. forget about PV for a sec. If you paid for power from the grid, and mined a bitcoin with it. What is your investment? and What is your return?

now, instead of spending money on grid, you spend money on your own solar power plant and mine bitcoin. What is your investment and what is your return?

 

[DerpsyDoodler]

Ok. forget about PV for a sec. If you paid for power from the grid, and mined a bitcoin with it. What is your investment? and What is your return?

now, instead of spending money on grid, you spend money on your own solar power plant and mine bitcoin. What is your investment and what is your return?

The only real follow-up question is how many watt-hrs does it take to mine a bitcoin?

 

[wattmatters]

If you build out a solar power plant, your investment is X. Anything that you can do with that power to generate income (regardless) is in scope as ROI or Y. You can wait for 15 years to sell your power at grid rates or you can do something with that power that increases its value more quickly. Turning it into bit coin is one way to do it (assuming it would be a profitable venture).

But you can also mine using grid power.

The only difference in ROI between using grid power to mine or building an off-grid power supply to mine is the cost of the energy. The return from the mining is the same in both cases, hence it nets out and you are only left with the energy cost differential.

 

[Jennifer]

I’ve created a monster ?

 

[wattmatters]

But you can also mine using grid power.

Just to show what I mean - here's the wholesale electricity price for South Australia over the past 7 days. This is the end of Winter.



The line shows the price for each interval with the price going up and down.

The line is dotted when the price is negative. It's was negative for about as long during the week as it was positive. IOW for those on a wholesale pass through plan they get a credit for consuming energy from the grid, and have to pay to supply energy to the grid.

Of course grid wholesale prices are not always that low, but this is not an uncommon scenario in this market. Also the time prices are negative overlap the same times solar PV is productive. That's no coincidence as Sth Aust has reached the point where at times solar PV alone supplies 100% of their grid demand, and many solar PV and wind farms have their output curtailed.

So if you were powering a crypto mining operation, would you spend money to put up your own solar PV, or instead get paid to use grid power?

 

[robby]

How much KWh would one need from your wonderful system to blow away the clouds that I have 300 days a year, Will?

Doing ROI calculations without the climate data is just silly, you mentioned several time the different local electricity cost, but not a single time the average weather conditions not mentioning a single time other constraints like shadows.
Worse, you pointed out the KWh one would get "every single day". Really?
Sorry, Mr Prowse, I won't follow you in that commercial!

And all these panels get mounted without any frames and any basement? (that easily cost more than the panels they carry)...

I think your asking for to much if you expect Will to outline every detail and problem. This video was made for his viewers and we all know that he lives in Nevada and has good annual weather for solar. We also know that he is using panels that are just lying on the ground and that is obvious from the video anyway.

I think the video was just giving people in an average location a rough idea of what to expect using a system like his that we intimately know about. Also five hours is a pretty standard number that I see used in calculations. I do agree that the video is a bit on the optimistic side when it comes to payback and equipment life span but I don't think anyone is just going to jump into EV charging and Coin Mining without doing a lot more research and tailoring the system for their needs, property size and location.

 

[wattmatters]

Also five hours is a pretty standard number that I see used in calculations.

5x array rated capacity is pretty optimistic. Not many places do that well - it would require the array to have tracking.

For a fixed array in southern Nevada without any output limitation you can expect on average around 4.7kWh/kW/day. Not many places in continental USA would be better.

4x is a better number to use as a ROT. Lower as you get further from the equator or live in wetter climates.

 

[upnorthandpersonal]

Excess capacity is not free. If your capacity utilisation goes up because you consume more energy it just means the per kWh cost of the energy you are using has been lowered a little. All that does is increase the operating energy cost differential with the grid.

Suppose the following scenario: someone spends 10K on an off-grid install. Because they made that investment, they get a consulting gig paying them 10K that year, essentially paying off the system after one year. Are you saying that every kWh generated from this point on is not free? Is this consulting gig not a ROI from doing the work? Analogy: is a job you get from studying for a certain degree not a ROI of the studying/capital investment of your degree, making you more (excess) money compared to someone without the degree once the student loan (if any) is paid off?

 

[robby]

Suppose the following scenario: someone spends 10K on an off-grid install. Because they made that investment, they get a consulting gig paying them 10K that year, essentially paying off the system after one year. Are you saying that every kWh generated from this point on is not free? Is this consulting gig not a ROI from doing the work? Analogy: is a job you get from studying for a certain degree not a ROI of the studying/capital investment of your degree, making you more (excess) than money compared to someone without the degree once the student loan (if any) is paid off?

Assuming your grid tied there is definitely a cut off point on power charges that make ROI impossible.
If your provider is selling at low fees like $0.13 per KWH I just cannot see a ROI no matter what.
You can only justify the expense based on backup connivence and doing your part to lower CO2 emissions. I am not going to include winning the lottery on bitcoins because that is not a reliable factor in any equation.
The flip side is when your power is expensive like over $0.43 a KWH. At that point you can repay the system cost within.a reasonable period.

 

[Steve_S]

Yeah that made little sense.

Comparing the cost of running an ICE vehicle with using solar PV to charge your EV would only be relevant consideration if you could not charge an EV with grid power. IOW the value difference solar PV brings is the marginal improvement over using grid power, not the jump from using petroleum to electrons.

REALLY ?
Spend $250 a month in GAS but get an EV and charge from your house solar and NOT have to spend $250 a month on Liquid Death that is paying you via savings.

Noticed your other comments, WHAT Exactly are you here for ? to spread FUD or what ?

 

[wattmatters]

Is this consulting gig not a ROI from doing the work?

Not if the consulting gig could also have been attained through using energy purchased from the grid.

If however you mean the consulting gig is specifically drawing upon their experience of setting up off-grid solar PV systems then again no since they could have gained an alternative form of experience or training unrelated to their solar PV investment which may well have paid just as well, or even better.

IOW the only consideration which matters for calculating solar PV ROI is the relative difference in the energy costs for the scenarios of with and without the solar PV system. Since you can do the same thing with electrons no matter their source, then any return from such activity is equal for both scenarios.

 

[upnorthandpersonal]

Spend $250 a month in GAS but get an EV and charge from your house solar and NOT have to spend $250 a month on Liquid Death that is paying you via savings.

Well, I understand his argument: if you have an EV you compare to grid vs. non-grid electric, not the switch from an ICE to an EV.

IOW the only consideration which matters for calculating solar PV ROI is the relative difference in the energy costs for the scenarios of with and without the solar PV system.

That's the part I disagree with.

 

[wattmatters]

REALLY ?
Spend $250 a month in GAS but get an EV and charge from your house solar and NOT have to spend $250 a month on Liquid Death that is paying you via savings.

Noticed your other comments, WHAT Exactly are you here for ? to spread FUD or what ?

I'm not sure if you are correctly reading what I'm saying.

When comparing EV v ICE there are two separate differences in the cost of energy.

The first and primary difference is the cost between gas (petrol) for the ICEV and electricity for the EV (on a mile for mile basis).

That energy cost difference is substantial (more so where we live). The biggest saving is made by not buying gas and instead buying electricity. I'm sure we can agree on that.

You may then save a bit more over using grid power to charge the EV by instead using a home solar PV system to charge the EV.

In this case the ROI component you can legitimately assign to the solar PV is the step change in cost over using grid power to charge your EV, and not the entire cost differential from ICEV gas to EV charged by home solar.

 

[wattmatters]

That's the part I disagree with.

Convince me.

For that you'll need to demonstrate that earnings or savings resulting from installing solar PV cannot also be attained via other means, e.g. by using grid power.

 

[Steve_S]

Im OFF Grid so grid to me is moot.
I get an EV and charge it at home with my own solar power, I'm not paying for fuel anymore and that saving is "banked". Any "Car Payment" is irrelevant as you have that with any new vehicle (usually). Instead of pumping $250 a month into a Big Oil Co that's 250 saved to bank account and I would consider that payback from my solar. With a 200mile + EV and plug in charge at home, any external charging would be minimal if at all (long trips only). Average driver drives <50 miles a day commute +.

 

[wattmatters]

WHAT Exactly are you here for ? to spread FUD or what ?

To engage and share. I have no idea what FUD is.

But if it helps, I have an 11kW grid-tied solar PV system as well as a 2.2kW off-grid system with 18kWh of storage.

I know exactly what the ROI of my grid tied solar PV system is, here's the latest update on the cumulative earnings and savings since it was installed a few weeks before the start date of the chart:

Im OFF Grid so grid to me is moot.

That's cool. But the main part of your saving was the decision to change over from an ICEV to an EV, not because the source of the electrons you fill it with happen to come from an off-grid system.

 

[upnorthandpersonal]

Im OFF Grid so grid to me is moot.
I get an EV and charge it at home with my own solar power, I'm not paying for fuel anymore and that saving is "banked". Any "Car Payment" is irrelevant as you have that with any new vehicle (usually). Instead of pumping $250 a month into a Big Oil Co that's 250 saved to bank account and I would consider that payback from my solar. With a 200mile + EV and plug in charge at home, any external charging would be minimal if at all (long trips only). Average driver drives <50 miles a day commute +.

What he's arguing, and which I follow to an extent, is that you can also charge the EV from the grid and that that should be the comparison (solar vs grid) ad not EV vs ICE.

Convince me.

For that you'll need to demonstrate that earnings or savings resulting from installing solar PV cannot also be attained via other means, e.g. by using grid power.

If someone has or develops the know-how to build a PV system, and can do consulting in the field because of that, these result in earnings you can not necessarily get through other means unless you want to argue that any and all jobs/careers/positions/opportunities are available to everyone and anyone. For example, yes, I could get earnings by becoming the president of the US and this would be more money than can be made consulting - but that path just isn't an option (I'm not even American).
This is the same as if you would state that earnings and savings from a degree in engineering can be attained by other means - which while true at face value, is not the reality: not everyone can become a CEO, and not everyone can become an engineer in the first place.

Bringing this back to the scope of solar vs grid, perhaps with an analogy: if you sell a man a fish, he will eat for a day. If you teach a man to fish, he will develop the opportunity to start a fish and chips business. People often talk about opportunity cost, I quote:

"The opportunity cost of an activity or option is the loss of value or benefit that would be incurred (the cost) by engaging in that activity or choosing that option, versus/relative to engaging in the alternative activity or choosing the alternative option that would offer the highest return in value or benefit."

My personal opinion is that if you can charge and EV from the grid, v.s. charging (part of) the EV power from a solar system, the latter will present opportunities that would otherwise not be available. Whether you act on those opportunities and turn them into earnings is up to the individual, but I argue that these can lead to earnings not attainable by just using grid power.