Math formula for calculation of solar power?

[russ]

A real community spirited type I see.

[Johnny Electriglide]

Electric bill per month

Johnny - If you read posts on the site by Sunking and others 20% discharge is recommended with a maximum draw of 50% - to maintain battery life.

I agree that the average person is a lazy type - hold their handout for others to do something for them.

If someone is to lazy to learn about a product before they buy then they deserve what they get. Having said that I have zero interest in doing anything electrical - not my interest. I end up trouble shooting various systems (electric, automation, alarm, CCTV etc) in my home and detest the time spent. Mechanical or structural is OK - Electrical or electronics is in another world.

The only thing wrong with your calculation is that you reference an 'average ' electric bill and compare it to your home which would use far less?

Most of us respect the service rendered to our country by combat vets. I did my time in 65 to 69 but never in combat. No need to drag it out in a post such as this though.

The good kids are still very good - the lazy-useless types are what drag things down.

I used the rough average of 100/mo. The actual I use with the rate, the monthly fees and taxes would now be 120/mo.(100Kw/hrs) I had used the map chart of min. winter sun hours in the sourcebook, and the electric use chart to find out my watt hours per day, multiplied by the 20% increase recommended for losses to get the 3000 watt hours per day. Divided by the 5 hours of winter sun to get a 600 watt array, full tracking or 40% more for fixed panels at the latitude angle. The roof of the shell I bought was at a 45* angle so I did not have the roof space. Also required at the time was the through the roof $600 DC GFI. So I decided on the full tracking pole mount well above the roof and braced to the inverter/battery split level shed and house barge rafter, 4' into the ground on 4" of concrete and set in 6" concrete all around.
The next year I added the addition to the house and another 232 watts of solar panels increased to 296 shortly thereafter. My calculations for power had gone awry when I was required to have more power sucking devices and wanted more than I originally planned for. This computer for one!!
When they saw I was not going to subsidize their lots by bringing in power lines, the 18K lot next to mine was offered at 11K. I refused. They could not sell to people who would either have to go to the expense of bringing in power or going to what they thought was expensive solar. The company folded and the county took the lot for back taxes owed. A guy bought it for 2500 and paid taxes the required 3 years. He realized he could not sell it either and offered it to me for 3,500. I bought it, erased the lot line and have 1.13 acre now. So part of my personal factor should include the savings on buying that lot!! I took advantage of people's ignorance of solar. I also got absolute water rights for 600' around my well, which meant that a number of lots would now need a cistern and could not put in a well without proving they would not affect my well--a nearly impossible hurdle. It should also be put in as a factor for getting the lot next door so cheap. This place was originally a ranch that was cut up into near 1/2 acre lots without regard to topography or drainage, and sold to people with a flat plan map. The county requires 35 acres to put in a well, but this land fraud area is grandfathered to where everyone can put a well on their lot, unless they are in a water right zone. The limit to building is a 30% (3 in 10) max slope, white water septic and well 100 feet from drainage and each other, or with regular septic 200". There are a great deal of un-buildable lots with insufficient water here. I let people know the codes and water situation whenever I can. That is my "community mindedness".
The fact is that this area is great for solar power, yet few have it out of the general ignorance of its ease of DIY cost. 5 hours a day average of winter sun in the "banana belt of the Rockies", or anywhere, is very good.

[russ]

Most weather stations offer a solar radiation reading as an option (requires optional pyranometer).

In my Davis weather station radiation is measured as 'global solar radiation (GSR)' unless a project is specifically designed for other purposes. GSR includes all light hitting the meter. Measuring in the same plane has little meaning really.

Easier to use the PV Watts calculator - a link is available on the forum page of the site. PV Watts takes into account factors that the casual user would never think of. The latest version is quite easy to use as well.

PV Watts uses long term averages from NASA data so it is correct over a 10 or 20 year period - any year may be significantly higher or lower.

If there is any shading, even from a power line, none of the calculators or even your weather station will accurately predict the potential production.

NASA has a large quantity of historical weather data available on their site - not only for the US but around the world.

Russ

[cleanergy]

Does anyone know if there are some mathematical formula for calculation of solar power? Or at least what parameters the electric energy depends on if produced by solar panel, like angle, days of sunny day, sunshine hour,latitude and longtitude,etc.?

If you could get a hold of some hourly solar irradiance data (measured in the same plane that you intend to put the array) you could roughly estimate what kind of output you could expect from an array of X kW (DC) rating. You would have to take into account multiple inefficiencies as well. I think this would give you the most accurate estimate though, probably not the easiest to accomplish...

[russ]

Johnny - If you read posts on the site by Sunking and others 20% discharge is recommended with a maximum draw of 50% - to maintain battery life.

I agree that the average person is a lazy type - hold their handout for others to do something for them.

If someone is to lazy to learn about a product before they buy then they deserve what they get. Having said that I have zero interest in doing anything electrical - not my interest. I end up trouble shooting various systems (electric, automation, alarm, CCTV etc) in my home and detest the time spent. Mechanical or structural is OK - Electrical or electronics is in another world.

The only thing wrong with your calculation is that you reference an 'average ' electric bill and compare it to your home which would use far less?

Most of us respect the service rendered to our country by combat vets. I did my time in 65 to 69 but never in combat. No need to drag it out in a post such as this though.

The good kids are still very good - the lazy-useless types are what drag things down.

[Johnny Electriglide]

Wow!!!

Yes, thick aluminum foil without gaps is a shielding method for the RFI/EMI that cause a buzz in phone lines and audio equipment. Some good Sinewave inverters have built in shielding that helps a lot. Back when I had dial up, it slowed down my internet connection speed by 3/4. I moved everything as far away as I could and use line filters. This is a real issue, not some loony tin foil hat garbage.
Desulfators certainly help with lead acid battery life, along with monthly equalization and keeping the fluid levels up, etc. In reading the Battery Book, I found out that the biggest increase in deep cycle lead acid battery life is to limit drawdown to 20% (battery still 80% full), NOT the 50% recommended before. Sure they can handle a 90% discharge but lose a lot of life. An old timer near me had been on inverter/L-16 battery and generators for charging for 25 years and still had some good L-16s that old. He later mounted solar panels.
Personally, now I would go for the nickel-iron---only because I'm not so broke!!
It is said my system did not pay for itself in 6 years. Here is how that worked out; The total system cost for a full tracking 600 watt array, twin com linked DR2424s, charge control center, 8-L16s, wires, pole, conduit, through the wall as standard 220VAC to the 100Amp panel with breakers was $9,300 in 1997-8. Average local electric bills were $100/month from my numerous inquiries. The IREA wanted $4,975 to bring power to my house, with anyone on the way able to tap in free. No gov't subsidies in this area, and at that time, for solar. The local solar installer at that time wanted $25/hr. It took 200 hours, so I saved $5,000 in labor. Subtracting the amount that the coal fired power company wanted to bring in power from the original $9,300 is $4,325. That is roughly 43 months of bills. I added the mancon and desulfators for $250, so that makes it a 46 month to zero. Real Goods gave the energy of manufacture of the system as another 2 year penalty. So in 2004 the system had paid for itself in saved bills from the power company, with an unknown amount of CO2 saved from going into the atmosphere. Many tons.
You are right in that not all solar installers are out to gouge the people, but many are. I saved roughly 53% by DIY. Others I have researched would save much more. I have also seen a 50% difference in price with shipping for panels and components that are the same, so it sure pays to shop around.
It is also sadly true that the average person is just not like the pioneers that tamed the west. Schools have eliminated shop courses and mechanical drafting, lowered science and math requirements, with the dumbing down I have witnessed for the past 35 years. The average person is too dumb, ignorant, or lazy to do the research necessary and the hard work of DIY solar electric system installation or building their own house. Perhaps one out of 400 tradesmen is capable, maybe less. In my 31 years(23 as foreman/sup't) in the building business, masters and real multi-tradesmen with brains to design were a rarity. Only one out of 20 worked in the trades, if that. That was the second career I was forced into, even though a disabled decorated combat veteran. I was a pro pilot COM ASMEL, H, I, and CFI for all, and AGI for 7 years, but hit by affirmative action increased requirements for my sex and race. I wasn't supposed to heavy lift again, ever. I was shot down 1/14/70 N of Xuan Loc RVN flying a Dustoff unarmed medical evacuation helicopter (UH-1H). Transmission hit and crash which broke my 2 lumbar cartilages with compressional damage to my spine. I John Wayned it back to combat in 16 days. As a foreman my wages stagnated from the invasion, for 20 years. I had to do it myself from economic necessity, and have the skills, brains, and experience.
I would like to think that many people, with determination, could do it themselves. Maybe many more could at least help to defray costs. That pioneer spirit that built this country must increase. It is a war to save the environment from that tundra methane self release tipping point, and a war for America, in America.

[Sunking]

That is what I did, and the systems paid for themselves, including energy of manufacture, in 6 years.

You were doing fine until you told this Propaganda. There is no Economic or Environmental ROI on battery systems. Simple pencil and paper will blow that statement right out of the water. You might get away with that on other forums, but not here. Battery systems at best case are only 50% overall efficient, and that can only be achieved if you utilize every watt hour possible each and every day which is impossible. Anyone even th elay person will know that claim cannot be true because not even a grid tied system can pay itself back with using other peoples money and have them finance 60% of the system.

Your battery desulfator claim is laughable and there is not one peer reviewed third party documentation to back up that claim. IEEE has blown that statement out of the water. You cannot stop the natural formation of lead sulfate crystals from forming on the battery plates. Only proper usage and maintenance can slow the progression down, no marketing gimmicks can get around that. If there was one ounce of truth to your claim battery manufactures would be recommending it as it would greatly benefit them to keep battery warranty claims down to a minimum. All you have is the charge manufacture claims, and that will not cut it.

[russ]

Some unusual and questionable bits of information -

1) Real Goods Solar Living Source Book -

I actually prefer the Sharp calculator - several easy to change parameters to show the effect of panel orientation. http://sharpusa.cleanpowerestimator.com/sharpusa.htm

2) Shielding most inverters from phone lines and actually everywhere with thick overlapping and no leak gaps aluminum foil under the drywall.

Anything like wearing aluminum foil underwear/hats?

3) It was said there is more system loss with batteries than with a grid tie system.

You can believe this if you desire but telling it to others as truth is not nice. There are additional losses due to the charging/discharging of the batteries.

4) Battery charging - I'll defer to Sunking on this point

5) save at least 50% on self installation -

You intend to say save 50% of overall cost I believe. Highly unlikely and most people are not all that competent to do the job. If an installer tries this type of markup he won't be in business long.

6) A battery based system paid back in 6 years? A wonderful thing the internet - everyone has full freedom to make whatever claims they want - proof or accuracy not required. Science has no meaning at all to some people.

Russ

[Johnny Electriglide]

Various places have them and phone or email assistance.

Does anyone know if there are some mathematical formula for calculation of solar power? Or at least what parameters the electric energy depends on if produced by solar panel, like angle, days of sunny day, sunshine hour,latitude and longtitude,etc.?

I used the calculator in my Real Goods Solar Living Source Book, and also talked to their techs before ordering. I found out things have changed with some of the information I was given back in 1997. Like design for an 20% and not 50% battery draw down over 3 days or whatever the average cloudy days in a row you can expect. Shielding most inverters from phone lines and actually everywhere with thick overlapping and no leak gaps aluminum foil under the drywall. Over sizing the system enough for adding power suckers you didn't originally count on.
It was said there is more system loss with batteries than with a grid tie system. Mostly it is the opposite. The power companies make money off you, you need special inverters and switching, plus are vulnerable to their system outages. Usually the system is larger, too, and the payback time longer.
I like having independence. The 410 Ah L16S batteries I have are equipped with mandatory desulfators to double their life.

http://www.batterytechsolutions.com/

However, there are the nickel iron batteries that last 25 years for almost 4 times the cost. The losses occur in DC systems when there are long wire runs, so designing a power room the shortest distance from the panels, and the battery vented sealed area also very close. Batteries lose power when too cold.
My main system was designed for winter sun intake of 3000 watt hours per day, with use 2500 watt hours and battery bank to last at least 3 days without sun. 24VDC system. Basically, in an area of 5 hours daily winter sun and 3 days min. battery bank sizing, each of the 410 Ah batteries has one 75 watt panel on max efficient full tracking. I would have needed 12 if fixed of the reflective glass panel type they are, with a 1" hail rating at at least a 30* from horizontal angle.
My garage system has 4 of the same batteries with 74 watts of fixed textured surface unbreakable panels at the average sun angle. They lose about 10% from being fixed, and it is a 12VDC system. My maximum amps was slightly greater than 33% less than the charge controller rating, and the first charge controller burned out. The charge controller should be over 50% higher rating than max amps from the panels at the very minimum. Double is better.
If you are in, say a 2.5 hour of winter sun area, then you would need twice as many panels, and more batteries, too, for more cloudy days and for improving the ratio of summer performance.
The biggest way to save on the systems is to first make accurate calculations on power needs, winter sun, cloudy days---then determine exactly what you generally need, and shop around for the best deals, sales, etc. for panels, controllers, power centers, lightning arrestors, ground rods, fuzes, monitoring, inverters, batteries, mounting supplies, and wires you'll need. Read up very well, get what tools you'll need and save at least 50% on self installation if possible.
That is what I did, and the systems paid for themselves, including energy of manufacture, in 6 years. After that, the money saving went into paying off the already low mortgage from sweat equity. I am now mortgage and electric bill free.
The Earthship portion rarely needs wood stove heat, and I wish the whole complex was one large Earthship. The main thing is I have plenty of power for my heavy electric guitars and tube amps!!

[Sunking]

Half full or half empty in my opinion. I'm sure there are a hundred ways to do this.

There are a few ways. even some you can find on the web from NASA, JPL, and Sandia National Labs is where most engineers develop their methods from. Point is people do not go to college for 4 to 12 years, spend another 4 or 5 years developing products and methods, have their work copyrighted and patented for nothing. It is a product or service like anything else you have to pay for. I can even sell you a program to do it for you, but I will be damned if I will give it away.

[russ]

Russ you are quite the hypocrite.
What I said was not a personal attack on anyone, let alone anyone specific.
You are a moderator on this forum? That is concerning.

Be as concerned as you wish - your statement was silly and I simply pointed that out.

It is 'true green' to make wild unsupported statements and then try to shift the blame when you are called out.

Russ

[russ]

All that I can tell you is that this is possible, and the reason you don't see it posted around the internet is because people are greedy. (I work for a company that specializes in this kind of research)

Oh! I see - a secret! A conspiracy! Those horrible people.

You may be a janitor for a company doing that kind of research - or maybe a secretary but you apparently know nothing but green blather.

We are not the kind of site that goes along with such trash talk.

Russ

[net_zero_energy]

Half full or half empty in my opinion. I'm sure there are a hundred ways to do this.

[Sunking]

don't see it posted around the internet is because people are greedy.

That is not greed my friend. People spends years and millions of dollars developing their product and methods. They do not give it away. Besides if you look around here I have detailed it out at 1000 times.

[net_zero_energy]

Possible..

All that I can tell you is that this is possible, and the reason you don't see it posted around the internet is because people are greedy. (I work for a company that specializes in this kind of research)