solar panels in the Land of the Sun

[ERD50]

Quote:

Originally Posted by Redbugdave ... A big part of the problem right now is battery technology. We need better efficiency and storage from batteries. I think we are on the cusp, but not quite there, yet. ...

For the average user, batteries are not even in the picture (except for the off-grid hermit scenario you posted). We don't need to store any solar PV until the day we are actually producing more watts than the grid can use. And even if we occasionally produce 10% or 20% more, it wouldn't be cost effective.

We are soooooooooooo far from producing more than we can use, it isn't even a consideration.

OTOH, since solar is intermittent, every watt of capacity of solar requires an equal watt of peaking power (usually a Nat Gs turbine). So once we exceed present peaking capacity, you can essentially add the cost of an NG plant to the cost of solar. It ain't cheap.

-ERD50

[scrinch]

After government subsidies I calculated about an 8 year payback prior to installing a 3kW system on my roof in 2006. In fact the performance of the system has been better than I assumed, and the power prices higher than I assumed, so the system has already reached payback. From here on in the system earns its ROI. Without the subsidies payback would have been around 15 years... not great, but better than a 0.5% return on a bank deposit. I'm pretty sure I wouldn't have made the investment without the government subsidy though.

[scrinch]

Quote:

Originally Posted by ERD50 OTOH, since solar is intermittent, every watt of capacity of solar requires an equal watt of peaking power (usually a Nat Gs turbine). So once we exceed present peaking capacity, you can essentially add the cost of an NG plant to the cost of solar. It ain't cheap. -ERD50

In California at least, solar power is peaking power, since hot summer afternoons are both when power demand and solar generation are at their maxima. But I think your point is that when solar becomes a really big component of the system, it will require either batteries or alternate base load capacity to carry the load at night.

[meierlde]

Quote:

Originally Posted by scrinch In California at least, solar power is peaking power, since hot summer afternoons are both when power demand and solar generation are at their maxima. But I think your point is that when solar becomes a really big component of the system, it will require either batteries or alternate base load capacity to carry the load at night.

But when you see demand swings of 100% in a day from say 30 gw at 4 am to 60+gw at 5PM you have a lot of peak energy before you hit base load. Now one thing might be to have the house cool hard in the AM and hold that level until close to sunset and shut off the ac for an hour or so. Fit the demand to the supply. After all we live with cooler temps in the winter. Say take the temp to 72 at 8:00 when the AC is not pumping against a very hot outside, and hold it there until say 5:00 pm and let it rise to say 78.

[ERD50]

Quote:

Originally Posted by scrinch In California at least, solar power is peaking power, since hot summer afternoons are both when power demand and solar generation are at their maxima.

Yes, solar is usually a good match for A/C on hot days, but if the sun gets blocked by clouds on a hot day, even for a few seconds/minutes, they need to spin up the NG turbines to make up the difference. You don't want a brown-out on a hot summer day. It isn't unusual in the Midwest to be very overcast/cloudy, and still be hot/muggy with lots of A/C load. But even if it happens only occasionally in a certain area, you still need to be prepared for those times.

Quote:

But I think your point is that when solar becomes a really big component of the system, it will require either batteries or alternate base load capacity to carry the load at night.

No. We already have plenty of capacity for night (coal, hydro, nukes, and wind - but wind is intermittent too, but better at night). What I'm saying is since solar is intermittent, for every unit of solar power you put in for the daytime peaks, you need an equal amount of some sort of backup that can spin up/down fast to keep the grid up when the sun goes behind a cloud.

That could be done with batteries, but AFAIK, NG turbines are far more cost effective, so I don't expect that to be the first choice for the majority of peaking power.

We don't need to store solar power at all, until we are actually routinely overproducing during the day. Even then, if storage costs more than running the alternatives, the economical thing to do is let that power go to waste. But that is a hypothetical - as I said, we are so far from routinely overproducing solar power, it isn't an issue. If we get there in 20 years, there will likely be options that are not available now.


-ERD50

[kramer]

Quote:

Originally Posted by travelover I recall traveling in Mexico years ago and every house seemed to have a black painted water tank on the roof. What a concept!

These are tinacos and they are very common in Mexico. They are there because water pressure is typically low in Mexico and it can also get turned off or to merely a dribble. So they keep a reservoir of water on the roof and have gravity to create water pressure. There is a pump to pump water up there. Richer places also have hidden underground water tanks. This typically has nothing to do with solar power.

My apartment complex in the Philippines also has one of these. But nothing to do with solar. There is a pump that gets turned on several times per day to pump water to the tinaco (I don't know the Filipino word for it).

In Mexico my Spanish teacher explained to me that one of his daily tasks, besides taking the garbage out, doing the dishes, etc., was to turn on the water pump at a non-peak hour and then it would get turned off by a sensor when it was full.

[travelover]

Quote:

Originally Posted by kramer These are tinacos and they are very common in Mexico. They are there because water pressure is typically low in Mexico and it can also get turned off or to merely a dribble. So they keep a reservoir of water on the roof and have gravity to create water pressure. There is a pump to pump water up there. Richer places also have hidden underground water tanks. This typically has nothing to do with solar power. My apartment complex in the Philippines also has one of these. But nothing to do with solar. There is a pump that gets turned on several times per day to pump water to the tinaco (I don't know the Filipino word for it). In Mexico my Spanish teacher explained to me that one of his daily tasks, besides taking the garbage out, doing the dishes, etc., was to turn on the water pump at a non-peak hour and then it would get turned off by a sensor when it was full.

Very interesting, thanks for the education. Now why are the toilets plumbed with 1.5" pipe such that toilet paper can't be flushed?

[clifp]

Quote:

Originally Posted by scrinch In California at least, solar power is peaking power, since hot summer afternoons are both when power demand and solar generation are at their maxima. But I think your point is that when solar becomes a really big component of the system, it will require either batteries or alternate base load capacity to carry the load at night.

In Hawaii, there is enough solar installed, that our peak demand time has now moved from the afternoon to 7-9PM. My solar system finally got switched on yesterday along with my 220 Volt charging for the Tesla. So this means I am going to charge the car during the day.

The final step in the process is one more city inspection, at which point they will activate my net metering agreement. This process can take anywhere from two weeks to 8 months. Fortunately, I don't owe any money and the clock doesn't start on my 20 year agreement until that is activated. So I am actually on the same as the electric company perfectly content if they drag their feet. Now this slow bureaucratic process maybe unique to Hawaii, but it does illustrate one of the problems of this distributed power generation.

[meierlde]

Quote:

Originally Posted by clifp In Hawaii, there is enough solar installed, that our peak demand time has now moved from the afternoon to 7-9PM. My solar system finally got switched on yesterday along with my 220 Volt charging for the Tesla. So this means I am going to charge the car during the day. The final step in the process is one more city inspection, at which point they will activate my net metering agreement. This process can take anywhere from two weeks to 8 months. Fortunately, I don't owe any money and the clock doesn't start on my 20 year agreement until that is activated. So I am actually on the same as the electric company perfectly content if they drag their feet. Now this slow bureaucratic process maybe unique to Hawaii, but it does illustrate one of the problems of this distributed power generation.

Which raises an interesting question. Given that HI does not currently use Daylight saving time, and a good part of the load is likley cooking and dishwashing, will the state move to daylight saving time, to move the meal time into the time it is sunny? That would move sunset to 8:15 pm from 7:15 and help the peak.

[kramer]

Quote:

Originally Posted by travelover Very interesting, thanks for the education. Now why are the toilets plumbed with 1.5" pipe such that toilet paper can't be flushed?

This is a question that millions of gringos have asked This article provides one detailed explanation:

Yucatan Living » Yucatan Survivor » Mexican Fosa Septica

A quick summary being that Mexican septic tanks are not designed for nearly as much paper usage as an American septic tank. So Mexicans never got into the habit of flushing paper. And this has continued even with more modern (non-septic) sewer systems as it is cheaper to build that way.


Also, from the same site, a detailed explanation of tinacos:

Yucatan Living » Yucatan Survivor » Yucatan Plumbing

[Badger]

Decades ago (70s) I had a subscription to Mother Earth News magazines and used some of their solar project ideas to reduce my electric bills. Some are still in use today. Probably the one DIY projects that I never got around to building but made the most economic sense was a batch solar water heater.

It was a simple black tank (from an old discarded water heater that was still clean inside from scale) in an insulated box with a reflective inside surface and a glass front. It was meant to be a splice in the water line between the water source and water heater to pre-heat the water.

On most days it could take source water at 65 degrees and bring it up to 100+ degrees before going to your water heater. I have my water heater set at 115/120 degrees because I don't see the need to heat water any higher and then have to cool it off to take a shower. It would easily pay for itself in a year (I live in Florida).

For really cold overcast days it could have an insulated cover and a by-pass valve. With the large mass of water in the tank (45+ gallons) freezing would not be an issue in at least half of the country and if left uncovered when sunny it still functions on cold days.

Can be used for both electric and gas water heating systems. It does not necessarily have to be on your roof as long as you have a sunny south facing spot in your yard. You can even get fancy and have an adjustable setting to angle the box for maximum efficiency at your latitude vs summer and winter solstice.

Cheers!