Puerto Rico’s power grid in ‘critical condition’; officials fear complete collapse

wwhitney

Senior Member
Location
Berkeley, CA
Occupation
Retired
I worked it out some time ago, so the specifics are hazy, but for the cost of the solar panels and batteries to keep my house going at up to 50 kW-hr/day (average), I could buy a 22 kW generator and all the natural gas to run it for about 10 years.
That's great! It sounds like a wash financially, and the PV + batteries will pollute less. A total win for off-grid usage.

Cheers, Wayne
 
Hmmmm, your solar puts out only 6-8 hrs a day, less in the winter and stormy days. Hydro is 24/7 365 days a year……..
I was referring to the second sentence of your post where you said this, "There is a lot of solar installs that were abandoned after the government money ran out.". I don't know exactly what you are referring to, and if that comment has any actual fact behind it (I doubt it) but let's go through the possibilities:

If a PV system is completed, there is no reason not to run it. Other than a little bit if maintenance, there isn't much to do. Power purchase agreements are already in place and someone is going to want the money for that power.

Now if you are referring to a system that was not completed because "government money ran out" that is also highly unlikely. First of all, any government rebate is probably a small fraction of the overall system financing. Here in NY it's about 10% of overall system cost. And (do I really need to say this??) I'm not sure how much you know about contacting, but typically an entity, whether it be government or private, doesn't just funnel money into something "until the money runs out". There are bids, performance bonds, payment schedules commensurate with progress, etc.

So I am highly skeptical your statement has any merit, and if it does it's probably a case of unscrupulous contractors and dysfunctional project oversight.
 

hillbilly1

Senior Member
Location
Atlanta,Ga
Occupation
Field coordinator/ technical support
I was referring to the second sentence of your post where you said this, "There is a lot of solar installs that were abandoned after the government money ran out.". I don't know exactly what you are referring to, and if that comment has any actual fact behind it (I doubt it) but let's go through the possibilities:

If a PV system is completed, there is no reason not to run it. Other than a little bit if maintenance, there isn't much to do. Power purchase agreements are already in place and someone is going to want the money for that power.

Now if you are referring to a system that was not completed because "government money ran out" that is also highly unlikely. First of all, any government rebate is probably a small fraction of the overall system financing. Here in NY it's about 10% of overall system cost. And (do I really need to say this??) I'm not sure how much you know about contacting, but typically an entity, whether it be government or private, doesn't just funnel money into something "until the money runs out". There are bids, performance bonds, payment schedules commensurate with progress, etc.

So I am highly skeptical your statement has any merit, and if it does it's probably a case of unscrupulous contractors and dysfunctional project oversight.
I had a picture of one in North Carolina I took a couple of years ago, but unfortunately it was on a phone I no longer have, or I would post it. I know of one on a city water pump station they removed several years ago, and have not replaced it. With the mess in California, I have no doubt they are keeping them up due to the power shortage, but in other parts of the US, they are just decorations just to make the utilities look “Green”. And the statement you made about a “little bit of maintenance” is untrue. We do work for IKEA, their electrical room is full of solar panels because they are constantly having to replace them. They were having issues with the inverters too.
 
I worked it out some time ago, so the specifics are hazy, but for the cost of the solar panels and batteries to keep my house going at up to 50 kW-hr/day (average), I could buy a 22 kW generator and all the natural gas to run it for about 10 years.
That analysis is quite flawed, for a number of reasons. First, I wonder if you considered generator maintenance and longevity. Most consumer standby generators are not intended for continuous use and I don't think would last long in such an application. Also most people living off grid are in locations that don't have cheap natural gas. Then there is the generator running 24-7 and who wants to list to that.

Next is off grid system design which I assume you know nothing about (it's ok, I don't expect you to, it's a very specialty area for sure). Typically an off grid system is not designed to run without generator support. Clearly it gets real expensive to provide 100% autonomy year round. In fact, a fatal flaw many off grid people fall into is NOT using their generator as much as they should. What you want is GENERATOR SUPPORT, that is frequent but brief generator use to support periods of heavier loading. The flaw is many people think they should hold off running the generator as long as possible - until their batteries are depleted, and then they are stuck running the generator for hours to charge them. So a properly designed system doesn't require as big and as expensive battery bank as you might think.

Finally, typically your electric consumption would go down substantially in an off grid situation. It's apples and oranges to compare on grid electrical needs with off grid electrical needs.
 
I had a picture of one in North Carolina I took a couple of years ago, but unfortunately it was on a phone I no longer have, or I would post it. I know of one on a city water pump station they removed several years ago, and have not replaced it. With the mess in California, I have no doubt they are keeping them up due to the power shortage, but in other parts of the US, they are just decorations just to make the utilities look “Green”. And the statement you made about a “little bit of maintenance” is untrue. We do work for IKEA, their electrical room is full of solar panels because they are constantly having to replace them. They were having issues with the inverters too.
I don't by any means claim to be the most knowledgeable and experienced solar guy out there, but I have a pretty decent and balanced resume in the solar industry. I have worked on several dozen megawatts of commercial roof and ground mount systems in multiple states and for multiple solar developers, one of which is a friend of a friend. Also done residential. Have a friend who has done exclusively solar, both commercial and residential for 8 years. I've got a pretty good sense of how this all works. I have not seen or heard of these things you say and I am pretty sure PV is not a scam,. But believe what you want.
 

gadfly56

Senior Member
Location
New Jersey
Occupation
Professional Engineer, Fire & Life Safety
That's great! It sounds like a wash financially, and the PV + batteries will pollute less. A total win for off-grid usage.

Cheers, Wayne
Not really; the roof ridge line is oriented north/south and there isn't enough real estate on the roof for sufficient panels at the unfavorable orientation.
 

drcampbell

Senior Member
Location
The Motor City, Michigan USA
Occupation
Engineer
... Hydro is 24/7 365 days a year
Um, no. Hydropower is limited by water availability. Operation of most large hydro installations is dictated by water allocation, not electricity demand.

And in recent years, that's becoming more & more of a concern:
 
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drcampbell

Senior Member
Location
The Motor City, Michigan USA
Occupation
Engineer
... Most consumer standby generators are not intended for continuous use and I don't think would last long in such an application. ...
Indeed. An air-cooled small engine in a standby genset can be expected to run about 4000 hours before it's worn out and needs an overhaul or replacement. And the recommended 25- or 50-hour oil-change interval might become a nuisance, not to mention the cost of the oil.

Contrast that with locomotive engines, which run 4000 hours between oil changes & other routine maintenance.
Different applications have different longevities specified and designed in.
 

gadfly56

Senior Member
Location
New Jersey
Occupation
Professional Engineer, Fire & Life Safety
That analysis is quite flawed, for a number of reasons. First, I wonder if you considered generator maintenance and longevity. Most consumer standby generators are not intended for continuous use and I don't think would last long in such an application. Also most people living off grid are in locations that don't have cheap natural gas. Then there is the generator running 24-7 and who wants to list to that.

Next is off grid system design which I assume you know nothing about (it's ok, I don't expect you to, it's a very specialty area for sure). Typically an off grid system is not designed to run without generator support. Clearly it gets real expensive to provide 100% autonomy year round. In fact, a fatal flaw many off grid people fall into is NOT using their generator as much as they should. What you want is GENERATOR SUPPORT, that is frequent but brief generator use to support periods of heavier loading. The flaw is many people think they should hold off running the generator as long as possible - until their batteries are depleted, and then they are stuck running the generator for hours to charge them. So a properly designed system doesn't require as big and as expensive battery bank as you might think.

Finally, typically your electric consumption would go down substantially in an off grid situation. It's apples and oranges to compare on grid electrical needs with off grid electrical needs.
I will grant you that generator maintenance was not part of the calculation, and I realize that what you get from Big Orange isn't designed to be a primary source. This was a rough order of magnitude calculation.

The exercise was specifically a comparison of grid vs off-grid with no fossil fuel support, other than the NG for the generator. I was going a bit beyond what, say, caribconsultant did down in PR.

I don't think your third point is valid. If this were a ground-up design, sure, you could take advantage of some energy saving features. Just because you go solar doesn't mean you're reducing your consumption somehow. This was about "can I replace utility with solar for this house and for how much".
 
I will grant you that generator maintenance was not part of the calculation, and I realize that what you get from Big Orange isn't designed to be a primary source. This was a rough order of magnitude calculation.

The exercise was specifically a comparison of grid vs off-grid with no fossil fuel support, other than the NG for the generator. I was going a bit beyond what, say, caribconsultant did down in PR.

I don't think your third point is valid. If this were a ground-up design, sure, you could take advantage of some energy saving features. Just because you go solar doesn't mean you're reducing your consumption somehow. This was about "can I replace utility with solar for this house and for how much".
Yes living off grid without fossil fuels is very expensive and I would not recommend it. Note for my third point I said "electrical consumption" not "energy consumption". Typically you would provide heat and hot water with (probably) propane.
 

petersonra

Senior Member
Location
Northern illinois
Occupation
engineer
I have a hard time believing that. It just doesn't make sense. Honestly it sounds like you don't know much about solar.

Yes living off grid without fossil fuels is very expensive and I would not recommend it. Note for my third point I said "electrical consumption" not "energy consumption". Typically you would provide heat and hot water with (probably) propane.
I am paying about 60 cents per therm for NG, not including delivery charges, taxes, etc.

That would make me about 9 kwHr of electricity on a decent genset. The fuel cost for the NG to generate my own is about what my current electricity cost is, but does not cover the generator cost, which is pretty substantial.
 

winnie

Senior Member
Location
Springfield, MA, USA
Occupation
Electric motor research
I am paying about 60 cents per therm for NG, not including delivery charges, taxes, etc.

That would make me about 9 kwHr of electricity on a decent genset. The fuel cost for the NG to generate my own is about what my current electricity cost is, but does not cover the generator cost, which is pretty substantial.

I pay much more for electricity and much more for fuel. But the cost of PV is about the same. This is why on paper PV looks like it makes sense for me.

Trying to bring this back around by spitballing some numbers:

Puerto Rico uses about 20,000,000 MWh per year. https://www.worldometers.info/elect...0,951,000 MWh,of its annual consumption needs).

Population of 3 million with lots of fluctuation https://www.worldometers.info/world-population/puerto-rico-population/

This gives an average consumption of 6.7 MWh per person

US as a whole is about 3,800,000,000 MWh per year with a population of 330 million, so roughly 2x per person more average consumption, but in the same ballpark.

Peak sun hours per day in Puerto Rico is about 5, so to get 6.7 MWh per year you need a 3.5 kW array.

I am going to make the spitball claim that all of Puerto Rico's electricity needs could be met using PV plus energy storage at a cost of $15,000 per person.

I know the above can be ripped apart many different ways; I'm just throwing it out for discussion.

-Jon
 

ggunn

PE (Electrical), NABCEP certified
Location
Austin, TX, USA
Occupation
Electrical Engineer - Photovoltaic Systems
... the statement you made about a “little bit of maintenance” is untrue. We do work for IKEA, their electrical room is full of solar panels because they are constantly having to replace them. They were having issues with the inverters too.
I have been designing commercial and residential PV systems for 12 or 13 years, and all of the commercial systems I designed are still up and running (I have designed hundreds of residential systems, so they are harder to keep track of, but service calls to my company for system failures are relatively uncommon). We have the occasional inverter issue, but most inverter companies have cheap extended warranties for 15-20 years, so when an inverter needs replacing it doesn't cost the customer anything. As for solar modules, other than the occasional hailstorm damage, necessary replacement of modules is pretty rare.
 

tortuga

Code Historian
Location
Oregon
Occupation
Electrical Design
I pay much more for electricity and much more for fuel. But the cost of PV is about the same. This is why on paper PV looks like it makes sense for me.

Trying to bring this back around by spitballing some numbers:

Puerto Rico uses about 20,000,000 MWh per year. https://www.worldometers.info/electricity/puerto-rico-electricity/#:~:text=Puerto Rico generates 20,951,000 MWh,of its annual consumption needs).

Population of 3 million with lots of fluctuation https://www.worldometers.info/world-population/puerto-rico-population/

This gives an average consumption of 6.7 MWh per person

US as a whole is about 3,800,000,000 MWh per year with a population of 330 million, so roughly 2x per person more average consumption, but in the same ballpark.

Peak sun hours per day in Puerto Rico is about 5, so to get 6.7 MWh per year you need a 3.5 kW array.

I am going to make the spitball claim that all of Puerto Rico's electricity needs could be met using PV plus energy storage at a cost of $15,000 per person.

I know the above can be ripped apart many different ways; I'm just throwing it out for discussion.

-Jon
This is what I am talking about. Nice numbers
I was just checking out this map of their generation:
https://www.eia.gov/state/?sid=RQ
And it looks like they have a few solar farms over 20MW.
I am also a big fan of hydro
I wonder if there are any ways to get the output of those 7 dams up?
Most of them are under 20MW.
 
I pay much more for electricity and much more for fuel. But the cost of PV is about the same. This is why on paper PV looks like it makes sense for me.

Trying to bring this back around by spitballing some numbers:

Puerto Rico uses about 20,000,000 MWh per year. https://www.worldometers.info/elect...0,951,000 MWh,of its annual consumption needs).

Population of 3 million with lots of fluctuation https://www.worldometers.info/world-population/puerto-rico-population/

This gives an average consumption of 6.7 MWh per person

US as a whole is about 3,800,000,000 MWh per year with a population of 330 million, so roughly 2x per person more average consumption, but in the same ballpark.

Peak sun hours per day in Puerto Rico is about 5, so to get 6.7 MWh per year you need a 3.5 kW array.

I am going to make the spitball claim that all of Puerto Rico's electricity needs could be met using PV plus energy storage at a cost of $15,000 per person.

I know the above can be ripped apart many different ways; I'm just throwing it out for discussion.

-Jon
Jon what are you using for your cost of storage numbers?
 

gadfly56

Senior Member
Location
New Jersey
Occupation
Professional Engineer, Fire & Life Safety
I pay much more for electricity and much more for fuel. But the cost of PV is about the same. This is why on paper PV looks like it makes sense for me.

Trying to bring this back around by spitballing some numbers:

Puerto Rico uses about 20,000,000 MWh per year. https://www.worldometers.info/electricity/puerto-rico-electricity/#:~:text=Puerto Rico generates 20,951,000 MWh,of its annual consumption needs).

Population of 3 million with lots of fluctuation https://www.worldometers.info/world-population/puerto-rico-population/

This gives an average consumption of 6.7 MWh per person

US as a whole is about 3,800,000,000 MWh per year with a population of 330 million, so roughly 2x per person more average consumption, but in the same ballpark.

Peak sun hours per day in Puerto Rico is about 5, so to get 6.7 MWh per year you need a 3.5 kW array.

I am going to make the spitball claim that all of Puerto Rico's electricity needs could be met using PV plus energy storage at a cost of $15,000 per person.

I know the above can be ripped apart many different ways; I'm just throwing it out for discussion.

-Jon
OK, so I found a source claiming that you need 2.8 acres of land for solar panels to produce 1 GW-hr per year. For PR, using your figures, that would be 20,000 x 2.8 or 56,000 acres. There is an NREL report that puts the figure at 3.5 - 4 acres per 1 Gw-hr/yr. Puerto Rico is about 3.4 million acres, so to a first order approximation, this appears doable.
 

ggunn

PE (Electrical), NABCEP certified
Location
Austin, TX, USA
Occupation
Electrical Engineer - Photovoltaic Systems
OK, so I found a source claiming that you need 2.8 acres of land for solar panels to produce 1 GW-hr per year. For PR, using your figures, that would be 20,000 x 2.8 or 56,000 acres. There is an NREL report that puts the figure at 3.5 - 4 acres per 1 Gw-hr/yr. Puerto Rico is about 3.4 million acres, so to a first order approximation, this appears doable.
But of course without massive amounts of storage a complete reliance on solar power on an isolated grid for energy production is not doable. More realistic with battery tech and availability where it is today would more likely be less PV, some storage, and significant baseline power production from nuclear or fossil fuels. Change is coming and inevitable but we can't do it all in one step.
 

winnie

Senior Member
Location
Springfield, MA, USA
Occupation
Electric motor research
Jon what are you using for your cost of storage numbers?

I was figuring the 3500W @ $4/watt retail cost for an install + 20 kWh@ $800 per kWh retail, and then halving that total because this is a wholesale project.

The 20 kWh storage number comes from 18 kWh energy used per day, but with a large fraction of that used during the day.

Like I said a very rough spitball calc for people to tear apart.

-Jon
 
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