Confused about Solar power.

[trancelistic]

Hi all, I'm Trancelistic from Holland. Please excuse my English in advanced since I'm not pro with it.

I was google-ing a bit arround about solar power and it got my attention. But the thing I had in mind can't be found.

I had an idea for a simple solar power (build/system) for just to power a laptop, and perhaps a strong 3~12volt LED light(s). Nothing else.
I was also thinking perhaps it can be portable?. E.g place it in a backyard or take it with me into the nature with my tent etc.
Is something like this possible? I Don't wanna power up my house or something like that. Simple because its not allowed at my place.
Just a solar paneel of some sort who also charges a battery or some sort that can power up my laptop decently for some hours a day.

If thats possible how to start and is it selfbuildable if I got buy the nessaserry parts?

I do know a bit about electro so I think I could be able to set it up with intructions.

Any 1 wanna help out a hobbiest?.

Greetz Me.

[Mike90250]

Figure the laptop at about 70 watts, on the average. Infinite run time while sun is out, if you had 120 watts of panels & good insolation.

Figure your watts * hours for your loads, and then you need to harvest from the solar, about 2* that much to account for recharging inefficiencies. If you have poor insolation, you need more panels to complete the harvest in the allotted time.

[russ]

Being in Holland where they have a few bad days/weeks in the winter an alternative charging scheme will be necessary - easy to do.

[trancelistic]

Figure the laptop at about 70 watts, on the average. Infinite run time while sun is out, if you had 120 watts of panels & good insolation.

Figure your watts * hours for your loads, and then you need to harvest from the solar, about 2* that much to account for recharging inefficiencies. If you have poor insolation, you need more panels to complete the harvest in the allotted time.

So, uhm. If I use a normal 220v to a 12 or 15 volt DC (ac?) adapter ( for a laptop normaly on the house net) and it ask 70 watt a hour (contantly?) Saying my Dc (AC?) adapter keeps my laptop on and charge my laptops battery at the same time.

I need a solar panel of 2 times 70 watt? SO a panel of 140 watt? But does a panel then also charge some kind of other battery to power my laptop in case I have no "solar power " because it was to cloudy or so.?

Really sorry about my English. I'm bad at it, I hope I made sense. haha.

[russ]

Really sorry about my English. I'm bad at it, I hope I made sense. haha.

You do great in English - just don't expect anyone here to say more than a word in Dutch!

[Naptown]

This reminds me of an old joke
What do you call someone who speaks two languages. Bilingual

Three languages. Trilingu

Only one language. An American

[trancelistic]

This reminds me of an old joke
What do you call someone who speaks two languages. Bilingual

Three languages. Trilingu

Only one language. An American

LOL you guys.
Well I'll await a reply<3

[Sunking]

So, uhm. If I use a normal 220v to a 12 or 15 volt DC (ac?) adapter ( for a laptop normaly on the house net) and it ask 70 watt a hour (contantly?) Saying my Dc (AC?) adapter keeps my laptop on and charge my laptops battery at the same time.

I need a solar panel of 2 times 70 watt? SO a panel of 140 watt? But does a panel then also charge some kind of other battery to power my laptop in case I have no "solar power " because it was to cloudy or so.?

Lets start from the beginning and include a dry run.

First thing to do is determine Watt Hours needed each day.which = Watts x Hours. So if you laptop uses 70 watts and you want to run it say 5 hours per day then is 70 watts x 5 hours = 350 watt hours. Multiply 350 wh x 1.5 to account for all system losses and you get 525 Watt Hours.

Next you have to determine how many Sun Hours you have on the shortest months of the year you want to do this. So if you operate year round you want to find the Sun Hours for your location. For example lets use 2 Sun Hours.

Next is determine panel wattage required. We know the Watt Hours needed and Sun Hours so all we have to do is factor out the time element (hours) to be left with watts. Watt Hours / Sun Hours = PANEL WATTAGE so 525 wh / 2 h. So 525 wh / 2 h = 262 watts minimum.

Next in line is selecting battery voltage and battery Amp Hour Capacity. For this size of a system you want to use a 12 volt battery. For the battery you want about 5 days capacity to account for cloudy days. OK you use 350 watt hours per day so 350 wh x 5 days = 1750 watt hours. OK we now know the battery voltage and watt hour capacity so now it is time to determine the Amp Hour capacity. Just like panel wattage all we have to do factor out the time element. So Amp Hours = Watt HOURS / Battery voltage. 1750 watt hours / 12 volts = 149 Amp Hours. So it would take a 12 volt 150 AH battery.

Next is to determine the Charge controller amp rating for a MPPT controller. Really easy Amps = Panel Wattage / Battery Voltage. So 262 watts / 12 volts = 21 amps. A 20 amp MPPT controller will work and save some money.

OK for this application just running a laptop just buy a 12 volt DC power brick for your laptop. There hundreds of them, just find one made for your laptop model. Using an inverter is more expensive and waste more power than a DC Power Brick.

There you go, now plug in your numbers for a real system.

[Mike90250]

...[/B]Next you have to determine how many Sun Hours you have on the shortest months of the year you want to do this. So if you operate year round you want to find the Sun Hours for your location. For example lets use 2 Sun Hours.

However, if you want, you can use a small generator to provide charge for the short and cloudy days. You just need to be aware of what is required for 100% solar, and adjust accordingly.

OK for this application just running a laptop just buy a 12 volt DC power brick for your laptop. There hundreds of them, just find one made for your laptop model. Using an inverter is more expensive and waste more power than a DC Power Brick.....

- well, maybe yes, maybe no. Who knows what % efficiency the 12V adapters are. The line powered adapters are pretty well regulated, with energy efficiency being a important factor. If the 12vdc adapter is less than 70% efficient, you may be better off with a 90% inverter and a 90% AC adapter. And you may need AC for some of the other things anyway, stuff has a way of creeping in and wanting to be used.