Can Solar Energy Reduce High Electricity Costs in California's Central Valley?

[Pengwuino]

So I was looking at my parent's power bill today because they've been complaining the bill is so high. I looked and as I knew for years, we get killed when we go pass what PG&E calls "300% over baseline". We live in the central valley in California where temperatures get to be up to 110 and that 300% over baseline rate is $.40/kwh. I want to try to convince my parents to install a small system at the house to at least reduce how much we're in that ridiculously priced tier. During the worst, we go something like 800kwh per month into that $.40/kwh tier. I want to convince them to get a small system that will supplement the power off the grid and I figure at this ridiculous rate, the return on investment has to be fairly quick. So I have a few questions for hte people in the know around here

1) Where can I find data on the actual usable energy that is received on average at a particular point in the US?

2) How much can they expect to pay upon installation per kw generation? And given say, a 2kw system, how much can they expect to generate in a given day (considering its not sunny all day!)? I was thinking about doing the real nitty gritty physics on this and I realized there's a crazy number of variables to consider such as how long the sun is up, the angling of the roof, the fact that in winter I highly doubt we even get near the 200%-300% of baseline rate. I'm going ot ask PG&E for some detailed records of our usage... hopefully they have them.

 

[JaWiB]

Start here: http://rredc.nrel.gov/solar/old_data/nsrdb/redbook/atlas/ It shouldn't be too hard to get some kind of estimate from that

As for costs, you'll have to look into the kind of incentives available. (http://www.gosolarcalifornia.ca.gov/csi/index.php)

 

[lisab]

Have they done other "little" things, like upgrading their insulation and windows?

 

[CRGreathouse]

Have they done other "little" things, like upgrading their insulation and windows?

+1. If the insulation isn't up to par, this has much better cost/benefit than solar, even with incentives. Of course it also pairs well with solar...

 

[Pengwuino]

The windows were upgraded to triple pane years ago. I think the insulation might be a problem though. I think this house is from the 50s. The main problem is the air conditioner I'm sure. I wonder if there's anything I can install to measure how much power the a/c takes. I have the coolest little meter you plug inline with anything you want that plugs into a wall and it tracks its power usage, but the a/c goes directly into the house wiring so it doesn't help :(.

 

[JaWiB]

If you know the voltage, you just need a current transformer :)

 

[Vanadium 50]

You will be shocked by how much solar costs. The solar panels are not the driving factor: the problem is that you get a couple of volts DC some of the time, when what you want is 110V AC all of the time. Getting from one to the other takes quite a lot of hardware and work by electricians.

The cheapest thing to do is often to immediately sell the power back to the power company rather than trying to use it yourself.

 

[Andre]

The http://library.thinkquest.org/20331/types/solar/problems.html.

My brother in law had this installed while I was there this month:

To the right are solar heat exchangers to heat water boilers, to the left are 16 solar electric panels. The lattitude of the building is about http://www.panoramio.com/photo/28211862, so you can do your calculations and he was told that the installation would be good for an average of 3000 watt, the legal maximum for private grants in France.

As soon as the installation was operational, a week or so ago, we observed the indicator giving a maximum momentarily yield of 1950W indicated on a bright day at noon, and about 400W maximum on a very dim rainy day. He was not very satisfied with that.

The heat exchangers meanwhile heated the warm water reservoirs to around 70C.

 

[Chi Meson]

I would encourage looking into thermal panels before PV panels. Since hot water can be 1/3 to half of your electric use excuding a/c , the payback is much quicker. The technology is more basic so the installation and maintenance is easier.

Considerations: is there a south-sloping roof? What is the pitch? Rule of thumb: it should be due south +/- 10 degrees, and the pitch should be your latitude +10 degrees.

If not, then consider ground mount or have it installed with those ugly frames that hold the panels away from the roof surface

And what is the coldest temp you get? If it only freezes a couple of times, then you have the option of putting in-line solar collecting tubes that omit the whole heat exchange fluid/pump/extra storage tank business. You would need to be sure that the tubes are bypassed and drained until the freezing season is over. Where I live, that is one third of the year, so it was not an option.

 

[Chi Meson]

The http://library.thinkquest.org/20331/types/solar/problems.html.

My brother in law had this installed while I was there this month:

To the right are solar heat exchangers to heat water boilers, to the left are 16 solar electric panels. The lattitude of the building is about 43 degrees north, so you can do your calculations and he was told that the installation would be good for an average of 3000 watt, the legal maximum for private grants in France.

As soon as the installation was operational, a week or so ago, we observed the indicator giving a maximum momentarily yield of 1950W indicated on a bright day at noon, and about 400W maximum on a very dim rainy day. He was not very satisfied with that.

The heat exchangers meanwhile heated the warm water reservoirs to around 70C.

If there is a single bad/sub-par panel in the works, or if there is any shadow at all on ay of the panels, PV yield will drop. This is my guess for the poor performance. I personally am still waiting for the right moment before I install PV on my perfectly-situated, south-facing garage roof.

 

[Andre]

If there is a single bad/sub-par panel in the works, or if there is any shadow at all on ay of the panels, PV yield will drop. This is my guess for the poor performance. I personally am still waiting for the right moment before I install PV on my perfectly-situated, south-facing garage roof.

No shadow there, but we have no insight in the proper condition and installment of course. I'll check on that.

 

[mheslep]

You will be shocked by how much solar costs. The solar panels are not the driving factor: the problem is that you get a couple of volts DC some of the time, when what you want is 110V AC all of the time. Getting from one to the other takes quite a lot of hardware and work by electricians.

Apparently installation is about 20% of the total cost. The hardware including Solar Modules, Batteries, Inverters and Controllers makeup the other 80%.
http://www.solarbuzz.com/solarindices.htm

 

[Ivan Seeking]

The cheapest thing to do is often to immediately sell the power back to the power company rather than trying to use it yourself.

That is by far the best way to do things. In the past, this wasn't possible as the power companies were not required to buy the power back, or they only paid a small percentage of what they charge you for the same power, but this seems to be changing quickly. California is probably the best of all States in this regard. Given a local smart-grid and a fair sales price for the power, it is just plain silly to isolate the power for your private use. It creates a lot of complications and expense for no reason. Also, this way the owner doesn't need to become an electrical engineer. It becomes transparent.

Pengwuino, I would definitely look into government programs and private funding. I know that there are or were companies in California that finance the up-front cost of the solar panels, and allow the owner to make monthly payments that ideally are [on the average] lower than the cost of your existing power bill. And there have been tons of government money for this sort of thing, esp in California, for a very long time now.

It would be very easy to do some checking locally to see what your expected yields would be, per unit area of panel. You live in a prime location for solar. If anything, you guys get plenty of sun! I have not been a fan of pv except in the areas that are great for solar, like the Sacramento valley.

If you can estimate the duty cycle of the a/c, you could make a reasonable estimate of the demand for power, based on the nameplate ratings. You might also be able to find the phase angle of the unit and calculate the active and reactive power, based on an inductive [noninvasive] current measurement at the a/c control box, or at a dedicated circuit breaker.

 

[Pengwuino]

I would encourage looking into thermal panels before PV panels. Since hot water can be 1/3 to half of your electric use excuding a/c , the payback is much quicker. The technology is more basic so the installation and maintenance is easier.

Considerations: is there a south-sloping roof? What is the pitch? Rule of thumb: it should be due south +/- 10 degrees, and the pitch should be your latitude +10 degrees.

If not, then consider ground mount or have it installed with those ugly frames that hold the panels away from the roof surface

And what is the coldest temp you get? If it only freezes a couple of times, then you have the option of putting in-line solar collecting tubes that omit the whole heat exchange fluid/pump/extra storage tank business. You would need to be sure that the tubes are bypassed and drained until the freezing season is over. Where I live, that is one third of the year, so it was not an option.

We do have a south sloping roof, not sure about the pitch though. We only get freezing temperatures a few times a year. Though that sounds like a lot of maintenance for my parents to handle.

I wonder how these businesses work where they actually generate power to sell directly to the utility. I noticed PG&E's wholesale purchasing rate was $0.09/kwh so I am just wondering if businesses like that just have economies of scale working that much in their favor...

 

[Pengwuino]

That is by far the best way to do things. In the past, this wasn't possible as the power companies were not required to buy the power back, or they only paid a small percentage of what they charge you for the same power, but this seems to be changing quickly. California is probably the best of all States in this regard. Given a local smart-grid and a fair sales price for the power, it is just plain silly to isolate the power for your private use. It creates a lot of complications and expense for no reason.

Pengwuino, I would definitely look into government programs and private funding. I know that there are or were companies in California that finance the up-front cost of the solar panels, and allow the owner to make monthly payments that ideally are [on the average] lower than the cost of your existing power bill. And there have been tons of government money for this sort of thing, esp in California, for a very long time now.

It would be very easy to do some checking locally to see what your expected yields would be, per unit area of panel. You live in a prime location for solar. If anything, you guys get plenty of sun!

I don't understand why it makes sense to sell back to the utility. We pay $0.40/kwh at that highest bracket and they wouldn't pay us that for the power we sell back. Just to make sure, we're looking for something supplementary to alleviate how many kwh we go into this $0.40 tier, not completely (or even nearly) replace our dependence on PG&E.

I can't imagine you have to go either 100% PG&E or 100% solar... that would suck.

 

[Ivan Seeking]

I don't understand why it makes sense to sell back to the utility. We pay $0.40/kwh at that highest bracket and they wouldn't pay us that for the power we sell back. Just to make sure, we're looking for something supplementary to alleviate how many kwh we go into this $0.40 tier, not completely (or even nearly) replace our dependence on PG&E.


I can't imagine you have to go either 100% PG&E or 100% solar... that would suck.

In solar friendly areas [wrt the power companies], which presumably includes your area, you use smart metering. To whatever extent you are producing power, your meter slows or even reverses direction. So the net value is what shows up on your bill. If you buy a system having an average output that exceeds your average power demand, you would get a check in the mail each month, not a bill.

The advantage is that you don't have to isolate your power sources. And you don't have to worry about batteries [a huge pain in the butt, dangerous, and expensive]. Best of all, you always use or sell 100% of the power you produce. Dedicated systems can be quite lossy. And you don't always need all of the power your produce. It is a timing issue between demand and supply. Net metering solves all of these problems. In effect, the grid becomes your battery system.

 

[Pengwuino]

In solar friendly areas [wrt the power companies], which presumably includes your area, you use smart metering. To whatever extent you are producing power, your meter slows or even reverses direction. So the net value is what shows up on your bill. If you buy a system having an average output that exceeds your avererage power demand, you would get a check in the mail each month, not a bill.

We use way too much power for that and wouldn't want to buy a system that big. I just want to take a slice out of that $0.40 tier come summer time. Just to lower their bill.

 

[Ivan Seeking]

btw, I had a bunch of late edits in my last two posts.

 

[Ivan Seeking]

We use way too much power for that and wouldn't want to buy a system that big. I just want to take a slice out of that $0.40 tier come summer time. Just to lower their bill.

AFAIK, if it is available in your area, net metering is by far the safest, least expensive, and easiest way to go. Try to do this yourself and dedicate a system, and you will quickly begin to see the practical problems. That is shade-tree mechanic level stuff.

You need to think like an economist and not an engineer!

 

[Pengwuino]

AFAIK, if it is available in your area, net metering is by far the safest, least expensive, and easiest way to go.

You need to think like an economist and not an engineer!

I am! We have newly installed smartass-meters . I'm still extremely confused. What's wrong with having a small system that just supplements your power draw from the grid? Even in winter i don't think we'd ever have a net production in power (or well... ok, maybe not THAT small of a system). So during summer, we'd see a decrease in the top tier and in the winter, maybe we'd sell some back... but most importantly is decreasing that top tier in the summer time.

 

[Ivan Seeking]

Do this the wrong way, and you will probably just lose money, and you parents would be justified in their skepticism.

 

[Ivan Seeking]

I am! We have newly installed smartass-meters . I'm still extremely confused. What's wrong with having a small system that just supplements your power draw from the grid? Even in winter i don't think we'd ever have a net production in power (or well... ok, maybe not THAT small of a system). So during summer, we'd see a decrease in the top tier and in the winter, maybe we'd sell some back... but most importantly is decreasing that top tier in the summer time.

How is that different from smart metering? That is how smart [net] metering works.

Otherwise, you have to dedicate loads to the panels, which becomes problematic.

 

[Pengwuino]

How is that different from smart metering? That is how smart metering works.

Otherwise, you have to dedicate loads to the panels, which becomes problamatic.

So... is that good? Smart metering that is. I think I'm extremely confused here.

Doesn't the system hook directly into your houses wiring? And when the power load is too much for the panels, it takes the rest from the grid? And if you aren't using all the power the panels are producing, it feeds back to PG&E?

 

[Ivan Seeking]

So... is that good? Smart metering that is. I think I'm extremely confused here.

Yeah, I'm a little confused about your confusion.

Doesn't the system hook directly into your houses wiring? And when the power load is too much for the panels, it takes the rest from the grid? And if you aren't using all the power the panels are producing, it feeds back to PG&E?

Yes. And your meter responds accordingly.

By "the system" I assume that you mean your net metering system? If not, then that [net metering] is what you need to do what you want to do. You can't just tie into the existing system and expect it to happen all by itself. You need the proper equipment - and it all has to be legal!

 

[Pengwuino]

Yeah, I'm a little confused about your confusion.



Yes. And your meter responds accordingly.

By "the system" I assume that you mean your net metering system? If not, then that [net metering] is what you need to do what you want to do. You can't just tie into the existing system and expect it to happen all by itself.

Ah! There's the problem. By system I meant the solar panel system. So I want to consider a small array of solar panels to just try to offset some of the ugly $0.40/kwh useage we have during the summer.

 

[Ivan Seeking]

Ah! There's the problem. By system I meant the solar panel system. So I want to consider a small array of solar panels to just try to offset some of the ugly $0.40/kwh useage we have during the summer.

And I'm telling you what it takes to make that happen at a profit [and without killing someone like a line worker with PGE]. Again, if you don't do things the right way, you will just lose money and would be better off not to even mess with it.

 

[Pengwuino]

And I'm telling you what it takes to make that happen at a profit.

Have smart meters?

 

[Ivan Seeking]

The system has to be designed properly and legal. You can do this even if the power company won't allow you to sell power back, if only to reduce your own bill. But you can't just rig something like this on your own. Not only does the inverter have to be in phase and voltage matched with the power company supply, you also have to be protected against backfeeding the lines in the event of a power failure, which could kill a PGE worker. This all has to meet the national electrical code standards and be approved for use by an inspector.

If you try to buy panels that are too small, you won't recapture the cost of the installation in a reasonable period of time... if ever.

The only other way to do this is to go with a dedicated or partially dedicated system, which can get really complicated and expensive, or become impractical from a supply-demand perspective - thus significantly offsetting or reversing any financial gains.

 

[Pengwuino]

OHHH No no no no no, I'm not actually putting it in, we'll get an actual solar installation company to do it! I'm just wondering if it's profitable. I know PG&E has installed smart meters here and they do buy power back, but I just want to make sure that it makes sense to buy a small solar panel system simply to help offset our power consumption from PG&E during summer when the bill just skyrockets. We'd still anticipate a bill every month... just not an $800 bill!

 

[Ivan Seeking]

OHHH No no no no no, I'm not actually putting it in, we'll get an actual solar installation company to do it! I'm just wondering if it's profitable. I know PG&E has installed smart meters here and they do buy power back, but I just want to make sure that it makes sense to buy a small solar panel system simply to help offset our power consumption from PG&E during summer when the bill just skyrockets. We'd still anticipate a bill every month... just not an $800 bill!

You need to determine the typical output per sq meter for your area based on real examples, the cost per unit area for the pv panels, the cost of power from PGE, the cost of the installation per sq meter of panel [including all PGE-related work], the life of the panels, and from that determine the minimum sized system that is profitable. There is some minimum size below which you will never see the pay back. Generally, you are looking at 10-15 years for a good or ideal system. Once you get into 20 and 30 year return cycles, you are into the life of the panel, and its a net zero gain.

I can tell you that I was looking to put in low-head hydro on my property. Just to get feedback protection, I needed to buy a $10,000 switch. How long would it take to pay for just the switch with my 5KW hydro, at 12 cents per KWHr?