solar panel and battery caluclator

[happycamperbrat]

This is the best one Ive found online. It's real easy to use to find out how many solar panels to get and the size of a battery bank http://www.freesunpower.com/system_sizing.php

[artvonne]

  Wow. It says I need 5 panels and 10 batteries just to run my fridge. And I would have to quadruple that amount to run the well pump. And thats with no lights, no TV, no computer, no clothes washing or drying. If I run everything I can plug in on that site, I would need 29 panels and 62 batteries?? Still no chest freezer, no extra TV's, no fans, no shop tools.

  100 years ago, many houses were heated using gravity. No fans, no pumps, everything was mechanical. Refrigeration started out primarily using eveaporation types like we have in todays RV's, and used very little electricity or little gas. Servell were a very popular fridge and many older people remember them. Early washing machines were hand operated, later driven my cute little gas engines. Clothes were dried on the line, wells were run with wind power. Some old farms had Jacobs wind generators, 36 volt DC generators charging a battery bank.

  What I found fascinating was an article I read, where around the 1920's Westinghouse sponsored the creation of things that used more electricity, even handing out checks to individuals and corporations that developed them. Soon they had compressor type refridgerators, electric stoves, electric water heaters, and also, electrification of the home furnace. Out went the gravity systems, and in went furnace's with low efficiency high energy fans and pumps with electric controls. It was no longer enough to simply have lights, you had to have everything cranking up that meter out at the pole. And then of course, came residential AC systems.

  While that was going on, DuPont was out selling his Freon, and working to rid the world of any type of refrigeration that didnt use it. Obviously Servell felt his wrath, as they began to focus on the dangers of having an ammonia refrigerator inside your home, and heaven forbid, one that used GAS too!! Hype a few fires or ammonia gassings and wave bye bye. There was a good 30 year period where just saying the name Servell would get an "oh, those are dangerous". Not too long back there was a government program that would pay you $100 if you signed a statement that you scrapped one. Wonder who sponsored that. They should have reversed it, and paid you $100 if you put one back in service and scrapped a compressor type.

  You can bet if everyone were forced to buy solar panels and batteries to run everything in their home, there would be a rapid awakening of ideas to cut power demands. And the electric car would meet a very sudden death.

 

[Slow Rider]

Art, I am curious and need for you to school me a bit.  I understand that ( according to the laws of thermodynamics ) heat rises and cold descends , but how do you use gravity to heat a home?

I am all about learning so please......learn me something

Frank

[happycamperbrat]

Art, if you read just below the calculator you will see it is based on the panels being 90 watt..... Many panels are made today that are a bigger wattage, so it may not be quite so bad.

[artvonne]

Art, I am curious and need for you to school me a bit.  I understand that ( according to the laws of thermodynamics ) heat rises and cold descends , but how do you use gravity to heat a home?

I am all about learning so please......learn me something

Frank

  Like a hot air balloon? Heat rises, cold descends. Some old houses had coal furnaces that heated air, and giant pipes 18 to 24 inches in diameter ran out like a giant Octopus to heat registers, and the heat would simply flow upward through the house to the the upstairs. Floor vents upstairs, would allow cooler air to flow downward, and once again big pipes were waiting to bring it down into the bottom of the air box. They were rather ineficient in the burning of coal, so they say, but they required no further energy to run other than your muscles to keep it fed. And they were silent.

  Other homes had gravity hot water heat. Again, using Coal, they would shovel it ino the fire box of a boiler. Hot water would rise up through pipes, and flow through cast iron radiators, or sometimes real cool copper ones. Valves controlled the flow. Up in the attic there would be a tank. From there, cooled water would flow down and into the bottom of the boiler, and the cycle would repeat. Again, they wernt wonderfully efficient at burning coal, but that was the only energy they used. No fans, no pumps, no transformers or ignitors, even the thermostats were mechanical. And like their air brother, they were equally silent. The biggest advantage to the boiler was it retained heat longer after the fire died. But the reverse was equally true, it took longer to get heat flowing again.

  When you consider that one of the single biggest energy users on your electric bill is your gas furnace blower fan and furnace controls, a modern approach back to a gravity system could pay off. The problem is HVAC people want to make a lot of money for as little effort as possible, and forced heat simpifies their job. There is a lot more head work to making a gravity heat system work right and most of the guys who built them were geniuses. And not knowing how to make them work was why most were ripped out by the 1950's. Sorta like the GM V8 being stuffed into Jaguars.

[Dave5Cs]

Of course the effect of constant burning coal in the home was not very good for the lungs either.

[belfert]

I have to imagine that gravity feed would not heat a house as evenly as forced air.  I doubt it was just lazy HVAC guys that caused gravity feed furnaces to go out of style.  Forced air was probably a huge improvement over gravity.

New houses are using a lot less energy overall than older homes even 40 years old that haven't been upgraded.  My house is 10 years old and I can heat and cool it for a fair bit less than older homes.

[happycamperbrat]

I used to live in an upstairs apartment....... I never had any need whatsoever to run the heater in the winter (except when the people downstairs went on vacation lol)

[artvonne]

I have to imagine that gravity feed would not heat a house as evenly as forced air. 

  Electricity and electric controls allowed you to leave the house for days and not have it freeze. But outside of that I never saw an old gravity heated house that heated unevenly or that was cold. There were a lot of them around Duluth when I was growing up, and a lot of the kids I went to school with lived in one. And it used to get darn cold up there.

[buswarrior]

THREAD DRIFT???

Back to the estimator in the original post.

This is a great attitude adjustment tool to check and see how badly undersized a busnut has been dreaming about sizing a solar system. Lots of good tutorials to read on the site.

Note, they have designed the estimator around 90 watt solar panels, 105 amp/hr batteries, 3 days reserve capacity to 50% discharge, and mid-America sunshine assumptions.

Busnuts are notorious at under sizing their battery bank systems, thinking they are saving money, only to harm the bank by deep discharging it, or having frequent generator run times to keep it topped up.

These folks at freesunpower have biased their estimator so that the user will rarely, if ever, exceed the design criteria. It is biased with "guaranteed delivery of service" in mind, NOT penny pinching minimalism.

A nice counter point to challenge us.

We've all seen, or perhaps we are, the busnut who constantly has to screw with the coach's systems to keep it all working... quick, get the generator running, quick, pull the plug on that before turning on this, darn, tripped the breaker again, darn, batteries are dead, no more TV tonight.... again.

Do you think the significant other will find this BS entertaining or stressful?

The coach and the busnut are in jeopardy if the foolishness makes stress.

happy coaching!
buswarrior

[happycamperbrat]

One thing for sure...... at least for me, this calculator is a reality checker  

[buswarrior]

Everything is a compromise, and intended use is a HUGE variable in deciding how to design the coach power systems.

Campground to campground is much different from weeks of non-stop boondocking.

Something as simple as the amount of ice used daily in your drinks, and where that ice comes from can be a significant calculation changer. Open the door, or dispenser?

In reality, we all end up with some sort of layering: power pole, inverter, charger, generator, engine alternator, solar, and beyond... And one or more separate battery banks.

With different methods of charging the batteries, and different power sources, compromises may be made on the sizing of the different components.

A busnut may choose to only have 1 day's worth of batteries, instead of the 3 in the estimator, and deal with cloudy days with the generator, similarly, cut the solar panel capacity down a bit for the same reason.

Each day's drive may provide the recharge via the engine alternator.

Solar is an excellent way to maintain the coach batteries while it is in storage, and for this purpose, quite minimal in size.

So, a little bit of this, a little bit of that, the trick is doing some math, confirming assumptions via BBS like this one, and seeing what gets you the system that will support your busnut lifestyle in a reliable and economically friendly fashion.

happy coaching!
buswarrior

[artvonne]

THREAD DRIFT???

  Only a lil. Cutting power loads will have a direct impact on solar panel/battery bank size. As you say, everything is a compromise. And really, the first place to start before looking at a solar power system should be at reducing demand loads as much as possible.

  Has anyone created decent flexible solar panels, something that would form to the roofs curvature? If the roof is going to be one big solar panel it would nice if it fit the shape, and would actually look better. Yeah I know you lose some capacity without flat panels angled to the sun, but...

  Paint on solar panels, that would be neat.

 

[Charley Davidson]

Lost all of my bookmarks about solar but there is a guy in the northeast that is building flexible solar panels that will contour to your bus top & possibly roll up as an awning. 

Solar has a bad return ratio for dollars spent and needs to come a long way yet. But with combined systems and efforts you can achieve off grid living in a bus rather cheaply.

I myself don't watch TV & haven't most of my life so doing without would be easy for me. I lived this winter with no heat and survived, went last summer with no A/C and survived so I could live OK off grid fairly easily.