Jump to content
Chapala.com Webboard

Questions for those who have solar power


Recommended Posts

We had solar power installed a few weeks ago and I really get a kick out of looking at the meter spin backwards (clockwise) and checking the digital panel to see how much power is being generated. 

I know if we are generating power, that is sending power to the CFE grid, then the meter turns clockwise. I've woken early when there is no solar power being generated, turned on a few appliances, and stepped outside to look at the meter. At that time, the meter is slowly turning counterclockwise, which means we are pulling energy from the CFE grid. 

Question #1:  If it were noon time, and the sun was high in the sky, and solar energy was plentiful, the meter wheel would continue to turn clockwise. However, if I were to turn on all the appliances in my household, would that wheel start to slow and begin to turn counter-clockwise therefore pulling additional power from the grid if needed?

Question #2:  If we were to experience a day in this household that is full of electric usage, all appliances are going and pulling more power than we are generating, would pa the digital panel express the energy output as a negative number? I don't mean with a negative sign, but I mean would it be a lower number than the day before? For example,  if on Monday we've generated 10 kilowatt-hours of energy but  we have used 11 kilowatt-hours of energy, would this -1 be reflected on the kilowatt hours from the previous, ie Sunday's usage? If Sunday night had ended at 250 kWh but with the net of -1 from Monday, with the number on the panel drop down to 249 on Monday night?

We have 8 panels and we are averaging about 12 kilowatt hours a day. But sometimes, when I have no appliances other than the refrigerator running, it seems we are generating about 13.3 kilowatt hours. However, on those days that I have the refrigerator and a fountain and a sprinkler system running, it seems like we are generating 12 kilowatt hours. So I guess I'm wondering: when I run more, does the panel show that I'm generating less?

Question #3: based upon my above calculations, I'm estimating and we are going to generate 300 kilowatt hours per month. Is that enough to run a few LED lights at night, a refrigerator a sprinkler system a couple of times a week, a floor fan at night, a computer that goes into hibernate mode, a television 4-5 hours a day, a washing machine twice a week, and all little bits and pieces of energy used for example for an electric doorbell, coffee maker in the a.m., microwave about 30 minutes a day?

We haven't received a bill from CFE yet so I'm trying to make an estimate. We will be installing a small pool requiring a 3/4 horse variable speed pump to save energy. Thinking that may require an additional 2 solar panels, as it seems each 2 panels generates 3 kWh a day.

 

 

 

Link to comment
Share on other sites

I can't answer  your questions but I can tell you that since we installed our 9 panels a few years ago, the worst bill we have received was 220 pesos for (then) one month and that was while one of us was having health problems and we ran a room air conditioner quite a lot because of that.  Like SunshineyDay, our last bill was 46 pesos which is the minimum for two months and represents the service charge for reading the meters.  In a couple of months or so you will get a better feeling for how much power you are using and know whether you need those extra two panels.

  • Like 2
Link to comment
Share on other sites

I ordered my system in 2007 and in those days there were occasional power outages, often for quite a few hours so I got not only solar panels but battery backup.

Almost no one gets battery backup these days, because there are so few power outages. Oh and to brag a little I have 28 photo voltaic solar panels. But that doesn't tell you much because while each of your panels are rated at near 300 watts, my first panels were only 170 watts.

I suspect that I would have maybe 20 panels at the higher wattage. Why so many? Mostly because of irrigation, I live on a steep hill on 3/4 of an acre

I love my solar panels. Keep on checking your usage, it's fun. I check mine every morning and log it in showing the amount sold to CFE and the amount purchased from CFE.

  • Like 1
Link to comment
Share on other sites

1 hour ago, johanson said:

I love my solar panels. Keep on checking your usage, it's fun. I check mine every morning and log it in showing the amount sold to CFE and the amount purchased from CFE.

Yes, me too. I started keeping a daily household activity log (first time in my life!) and I have been entering the amount sold to CFE. Haven't figured out how to determine the daily amount purchased from CFE  yet.

And you're right, it is fun. 

Link to comment
Share on other sites

I have 13 panels, and last month paid for the previous two months, $46 p. We have a pool, the pump runs for about three hours per day, numerous electrical gadgets running.

If your interested in tracking usage, check out http://123solar.org/

I have this running on a raspberry pi, connected to the inverter, and access it thru a web browser. Heres a screen shot:

 

Screenshot from 2017-05-14 05-48-43.png

Link to comment
Share on other sites

12 hours ago, kimanjome said:

We had solar power installed a few weeks ago and I really get a kick out of looking at the meter spin backwards (clockwise) and checking the digital panel to see how much power is being generated. 

I know if we are generating power, that is sending power to the CFE grid, then the meter turns clockwise. I've woken early when there is no solar power being generated, turned on a few appliances, and stepped outside to look at the meter. At that time, the meter is slowly turning counterclockwise, which means we are pulling energy from the CFE grid. 

Question #1:  If it were noon time, and the sun was high in the sky, and solar energy was plentiful, the meter wheel would continue to turn clockwise. However, if I were to turn on all the appliances in my household, would that wheel start to slow and begin to turn counter-clockwise therefore pulling additional power from the grid if needed?

Question #2:  If we were to experience a day in this household that is full of electric usage, all appliances are going and pulling more power than we are generating, would pa the digital panel express the energy output as a negative number? I don't mean with a negative sign, but I mean would it be a lower number than the day before? For example,  if on Monday we've generated 10 kilowatt-hours of energy but  we have used 11 kilowatt-hours of energy, would this -1 be reflected on the kilowatt hours from the previous, ie Sunday's usage? If Sunday night had ended at 250 kWh but with the net of -1 from Monday, with the number on the panel drop down to 249 on Monday night?

We have 8 panels and we are averaging about 12 kilowatt hours a day. But sometimes, when I have no appliances other than the refrigerator running, it seems we are generating about 13.3 kilowatt hours. However, on those days that I have the refrigerator and a fountain and a sprinkler system running, it seems like we are generating 12 kilowatt hours. So I guess I'm wondering: when I run more, does the panel show that I'm generating less?

Question #3: based upon my above calculations, I'm estimating and we are going to generate 300 kilowatt hours per month. Is that enough to run a few LED lights at night, a refrigerator a sprinkler system a couple of times a week, a floor fan at night, a computer that goes into hibernate mode, a television 4-5 hours a day, a washing machine twice a week, and all little bits and pieces of energy used for example for an electric doorbell, coffee maker in the a.m., microwave about 30 minutes a day?

We haven't received a bill from CFE yet so I'm trying to make an estimate. We will be installing a small pool requiring a 3/4 horse variable speed pump to save energy. Thinking that may require an additional 2 solar panels, as it seems each 2 panels generates 3 kWh a day.

 

 

 

Your output meter shows the production of the solar panels. It does not matter if that production is going to the house or cfe. Production is not affected by useage.

  • Like 1
Link to comment
Share on other sites

We got solar about 6 months ago (10 panels).  We have received two bills so far.  Both bills were for 2 months and both showed zero net usage. We are making far more than we are using.  But the minimum charge we had to pay for 2 months was 75 pesos.  Why are all the others only paying 46 pesos for 2 months?  I realize it's a small thing, but it seems odd that every one else I talk to that has solar panels is paying 46 minimum and we are paying 75 minimum.  Anybody else out there paying 75 minimum and know why?

Link to comment
Share on other sites

The panel only shows what you generated. If you want to check total usage per day you have to read the meter let's say in the morning of day 1. At the end of the solar day or the morning of  day 2 read the panel and again the meter. You take the net of the in/out of the meter and add it to the panel production. Unkess you are overproducing the meter net will be negative meaning you used some CFE power in addition to what you generated.

In Ajijic the average sun hours per day is 5.7. You'll be using some CFE power overnight up until the time the sun gets high enough to start cranking out some kWh. At that point you'll use some and send the rest out into the system.

I wrote a spreadsheet to enter the total production at tne end of each month to tell me the averages of my system over the year. Some months are better than others. After 5 years the averages aren't changing much.

  • Like 1
Link to comment
Share on other sites

The number of panels one has is meaningless unless you know the output of one panel.  Years back they were all 128W, then 256W, now I understand they are over 300W.

I have 20 panels each 128W or 2.56KW total.  Know the total out put of your system and use that number to describe it.  Number of panels is useless information.

  • Like 1
Link to comment
Share on other sites

 Number of panels is useless information.

Well said.

Much information could be gathered by those who want to know more about solar electricity if those who already have solar electricity would provide pertinent information.

  • Like 1
Link to comment
Share on other sites

We have had solar for a few months and our bills have been 46 pesos but a couple of weeks ago we had four min-splits installed and they have run pretty much all day every day so I am wondering what to expect on our next bill.  The units are two one and a half ton and to one ton units.  I have to say that even if it costs us more, and I am sure that it will, it has been wonderful being able to cook without suffocating and to sleep comfortably at night; as for the dry air and the decrease in dust due to the closed windows we are feeling pretty spoiled here! 

Link to comment
Share on other sites

You are going to see a very large increase in energy consumption, If you only had one A/C that used 1000 watts per hour and you ran it 10 hours per day, that would mean that you are burning up to 10 KWH extra per day or 300  KWH  per month. and that would mean you are using enough, if you did not have solar panels, to go into DAC or the very expensive CFE charge rate.

Now you say you have four units. I sure hope they are not in cooling mode for very long each day,  Oh I have no idea how many watts a 1 or 2.5 ton unit uses. But I bet you will be buying more panels.

Oh and why is the minimum charge 46-7 pesos every two months?  It is because you are charged for 25 KWH per month whether you use any electricity or not, Luckily extra KWH generated are recorded and put in your account and given back to you during any billing period you do not generate enough power.

 

Link to comment
Share on other sites

Efficiency of mini-splits vary a lot. Typically if you pay for a high quality unit up front your electric usage is less.

To minimize surprises just get a piece of paper and write down the total kWh produced from the panel and then the in/out at the meter at the same time each day. From these 3 numbers you can compute total daily usage. It will vary somewhat on days you use washing machines, dryers or dishwashers but the remainder should be pretty constant.

Measure plug in devices like refrigerators with a kill-watt. Any electronic device that is warm to the touch is drawing power.

Not all solar systems generate power the same. The type of panel, orientation and elevation angle all come into  play and can cause results to vary. Angle of the sun throughout the year and cloud cover also come into play.

When I got my 3.072 kWh system (24x128 watt thin film panels) almost 5 years ago I was told to use a sun hour value of about 5.8. 3.072 times 5.8 yields an average of 17.8 kWh per day. My system peaks at about 20 when everything is humming but since installation that lifetime average of between 17 and 18 has held up.

Link to comment
Share on other sites

Thank God they never promoted those All Electric Homes here like they did in the USA in1965-75's. Mexico is one of the most expensive cost per KWH in the world. This may be the only place on the planet where you can get a 2.5 year pay back at 26¢ per KWH. 

Link to comment
Share on other sites

17 hours ago, johanson said:

... Luckily extra KWH generated are recorded and put in your account and given back to you during any billing period you do not generate enough power.

 This means if I generate 300kWh in a month but use only kWh200 that month, the surplus 100kWh is credited to my CFE account to be used during those months I do not generate enough to cover my electric usage: correct?

How long is the "credit" held on my account?  Must I use it the following month, or does the credit sit in my account until it is completely used up? In other words, does whatever the credit is, does it continue to accrue and roll  I over? If I generate a surplus of 100 kWh every month for a year, and never draw from them, will I have a total credit of 1200 kWh at the end of the 12 months? Does the credit expire?

Quote

 

 

Link to comment
Share on other sites

Yes you are correct. You receive credit for your surplus. When I first got my panels in 2008, there was no limit as to when I had to use up my surplus. That has changed and I understand but have not confirmed that you have to use up the extra power you saved in the year that you earned it. Apparently your reserve or power saved is reset to 0 at the beginning of every year.

Please could someone confirm the date for emptying your power saved account and year end? Thanks

Link to comment
Share on other sites

It shows how much excess I sold to CFE and I subtract that from how much I bought back and that is the surplus, And somewhere on the back of the bill is total extra power that I generated  and saved up over time. Going by memory here in rainy Seattle.

Link to comment
Share on other sites

On 5/14/2017 at 9:04 AM, Mostlylost said:

Is your rate still DAC?  The minimum charge is based on a minimum  KWH charge.  It took 3 cycles for my DAC rate to go away.

Thanks Mostly Lost. No, it is not DAC.  We had two meters (two accounts). One was DAC, that account was completely closed.  The other account was never DAC. It is that account that continues with our solar power.  I'll wait one more cycle.  If it is still 75, I'll go ask them about it.  Thanks!

  • Like 1
Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

 Share

×
×
  • Create New...