Tony Masterson

Will the output voltage always be stable at 16.5 volt but the current depends on the brightness of the sun?

If yes, does it really matter how big the load is?
To put this to the extreme, if I would connect a 12v, 2kW heater would it just heat between 0-100Watt depending the brightness of the sun?
Or will that damage the panel.

I'm a bit confused about what the voltage of the panel is.
The warning states "Solar module has full voltage even in very low light"
I guess that's the  Voc of 21.0V.
The working voltage is 17.5 Vmp when under full load (100 Watt)

Does that mean if I connect a 50Wattt load the voltage is about halfway open and full load voltage?

My main question is this. Suppose I permanently connect a 200 Watt, 24V heater directly to the panel without any regulating electronics in between.
Will it damage the panel because it will be in constant overload?
Will the minimum voltage be 17.5V even when overloaded (or short circuited)?
Will the panel deliver between 0-100W to the heater depending on the strength of the sun?


PS. I'm aware a 200W, 24V heater will have a lower rating at 17.5V. I just don't want to overcomplicate my question

Bought a pressure cooker especially to add to the above tests.
But I'm stuck now because I have no idea how to measure with PC.
Can't even cook with it (yet)

But one thing I can already say for sure: It makes a huge difference.
I put in a handful of dry black eyed peas.
Put it on 3 Kw for maybe 3 minutes.
It kept blowing steam like crazy. Much too hot.
Then I moved it to my 1 kW burner to maintain heat.
Still kept blowing steam like crazy.
Then I turned the heat on minimum which is I think 0.3 kW. Only then the over pressure valve closed.
Let it cook for 10 mins I think. I really had no clue what I was doing (and still haven't).
But the bean were so soft they started falling apart. They even started dissolving because the water was dark brown and half of the beans was empty. By that I mean the husk was still there but half of what's inside was gone.

So I've cooked  the unsoaked beans way, way to long. And even that was much shorter that cooking pre-soaked beans the ordinary way.

Added a few tests and some extra info to my initial tests.

Mark Brunnr wrote:BuildItSolar has a list of sites here: https://builditsolar.com/References/SunChartRS.htm one of those might have some info for you.

There are sites like https://unboundsolar.com/solar-information/sun-hours-us-map which give some general numbers for the annual average hours per day. I would think that it really depends if you are doing this on-grid or off-grid though, as on-grid it's usually about generating the most power on average and filling in with grid power otherwise.

Those links are like a treasure chest for me...


Few links I've collected:
TILT:
http://www.solarelectricityhandbook.com/solar-angle-calculator.html
https://footprinthero.com/solar-panel-tilt-angle-calculator
https://solarsena.com/solar-panel-tilt-angle-calculator/
http://www.solarelectricityhandbook.com/solar-angle-calculator.html

https://www.thesolarnerd.com/blog/optimal-solar-panel-tilt-most-calculators-are-wrong/
https://www.thesolarnerd.com/calculator/

kWh forecast

Forecast Solar - Extremely basic
https://forecast.solar/
https://doc.forecast.solar/doku.php?id=api:estimate

https://api.forecast.solar/estimate/:lat/:lon/:dec/:az/:kwp
https://api.forecast.solar/estimate/45.67890/4.56789/123

SOLAR ATLAS - Best
https://globalsolaratlas.info/map?s=45.67890,4.56789&m=site

PVWatts® Calculator - Good
https://pvwatts.nrel.gov/pvwatts.php
https://www.energy.gov/eere/solar/sunshot-2030

S Bengi wrote:
It's usually cheaper and better to just install more solar panels on the roof vs fussing about tilt angle or worse solar tracking.

I'm not planning on tracking but I might optimize for a certain season.
Or I may do 'tracking' by manually changing the angle 2 or 4 times a year.

A 10degree tilt angle is enough for the solar panel to be self-cleaning.

Once found an app with its location always defaulting to Spain. The all around optimum angel it gave was horizontal, all year around. Great output but also a lot of cleaning.
According to this site solar tracking is vastly overrated. Not just because it's expensive, but also because minimal yield differences.
He starts with saying most calculations are only true when you live on a planet without an atmosphere. Refraction, diffusion, pollution, clouds, etc all change the optimum.
His conclusion:

For example, when I set my tilt angle to 25° - a pretty large deviation from the optimal tilt - it results in only a 1% reduction in overall annual power generation.

Why is this? Buffalo is often fairly cloudy, which means that diffuse light plays a large role in the power generation for my system. Because the light is diffuse, it doesn’t matter as much if the panels are perpendicular to the sun.

His optimal tilt is 33° and a 8° deviation only gives 1% difference.
This is likely old info for most around here but not for me. I own exactly 0 kW in solar panels.
I'm researching a bit to make the best choice for my situation.





https://www.thesolarnerd.com/blog/optimal-solar-panel-tilt-most-calculators-are-wrong/

I'm looking for websites/software where I lookup all sorts of info about solar panels.
- Historical  kWh output.
- Output forecast.
- Optimal orientation of the panels (throughout the day)
- Nice graphs.

I once found such a site. Free. I allowed me to configure all sorts of things like the location were I live, how many panels I have etc.
I lost the link, and that's why I'm here to ask if anyone knows about a website and/or software that provides such data.
Must be Windows software or work in a browser. I'm not really interested in anything that only works on a phone.

r ranson wrote:total noob question: can people live in a van in the winter?  Are there ways to heat a van that doesn't involve a lot of fuel?  

I'm not the traveling type but if I would live in  a van I would follow the 70F weather :-)

S Bengi wrote:The newer batteries, LiFePO4 cost a little less than $1000 per 1000Whr. Technically someone could build one for about 1/3 that cost.

Are the blue square one worth considering?
https://www.aliexpress.com/wholesale?trafficChannel=main&d=y&CatId=0&SearchText=LiFePO4<ype=wholesale&SortType=price_asc&minPrice=40&maxPrice=999&page=1&groupsort=1

An old thread. The book is likely already in second print but here are some ramblings written by someone who needs a manual to boil water :-)

No fluff
No filler text of any kind. If you must, do it somewhere in the back of the book. No need how old you are where you live with your beautiful wife and 3 children.
The history of a skillet is for another book. I always feel scammed by such books. I paid for 300 pages but get a mere 150 pages. I wouldn't have that same feeling when buying a 150 page book at the same price.

Don't be vague:
Define the amounts very clearly. "A cup" how big is a cup? I have cups that vary 50% in size. How large is a medium apple? What's a little vinegar?
"Add ... to taste". I'm buying a cooking book because I don't know how much .... is needed.
"Until done", when is it done? What does 'done' look like? Medium, rare or well done. Etc
Avoid 3-4 servings. It's 3 or it's 4. I understand some people eat less and some eat more. The author may be a small eater and I eat like a hog. Soon I learn that what the author calls a serving isn't enough for me, and just have to scale up the recipe. If 3-4 means 3.5 the author should scale the recipe up or down.

Generic names
Use generic names. That will increase your audience. American brands often aren't for sale in the rest of the world. But when using generic names you are more likely to sell on other continents.

Uniformity
Every recipe starts at the top of a new page. Each page has exactly the same format. For example time, calories and how spicy it is.
But also each recipe is for one person. If needed just double, triple, etc.
Not one recipe for 6 people and the next one for 4 people.


Ingredients
Use the bare minimum of ingredients. Not 50% extra ingredients because it looks cool.
Try to use a certain ingredient in many recipes. Often I  have to buy an ingredient and what's left I can't use because it's used in no other place in the book.
If using prepacked stuff try to use up the whole package. Especially with stuff that spoils easily. You know, add a tea spoon of coconut juice and pour the remaining quart down the sink :-)

Options
It's a thanksgiving recipe with turkey. Turkeys tend to be big, too big for small families. So suggest chicken instead and explain what it does to the taste, cooking time, halve all other ingredients, etc.

Audience
Write the book for a certain audience.
Absolute beginner or advanced.
Expensive or cheap.
Etc.

A recipe on how to boil an egg should never be in the same book as a recipe that makes a 5-star chef nervous. If you do, most of the recipes are useless for whoever buys the book. How odd would in be for someone who's doing a masters in math and finds grade school math stuff in the book?

Don't be long winded
Write a recipe and then cut down the text by at least 30%. Often things can be reworded to a much shorter and clearer text. Long winded is often the hallmark of someone trying to hide something. Just watch a politician talking an hour without saying anything :-)