# Convincing someone to go Solar!

1. Aug 28, 2010

### 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.

2. Aug 28, 2010

### JaWiB

Start here: http://rredc.nrel.gov/solar/old_data/nsrdb/redbook/atlas/ [Broken] 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)

Last edited by a moderator: May 4, 2017
3. Aug 28, 2010

### lisab

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

4. Aug 28, 2010

### CRGreathouse

+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...

5. Aug 28, 2010

### 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 :(.

6. Aug 28, 2010

### JaWiB

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

7. Aug 29, 2010

Staff Emeritus
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.

8. Aug 29, 2010

### 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.

Last edited by a moderator: Apr 25, 2017
9. Aug 29, 2010

### 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 :yuck:

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.

10. Aug 29, 2010

### Chi Meson

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.

Last edited by a moderator: Apr 25, 2017
11. Aug 29, 2010

### Andre

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

12. Aug 29, 2010

### mheslep

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

13. Aug 29, 2010

### Ivan Seeking

Staff Emeritus
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.

Last edited: Aug 29, 2010
14. Aug 29, 2010

### Pengwuino

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... 15. Aug 29, 2010 ### Pengwuino 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. 16. Aug 29, 2010 ### Ivan Seeking Staff Emeritus 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. Last edited: Aug 29, 2010 17. Aug 29, 2010 ### Pengwuino 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.

18. Aug 29, 2010

### Ivan Seeking

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

19. Aug 29, 2010

### Ivan Seeking

Staff Emeritus
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!

20. Aug 29, 2010

### Pengwuino

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.