Tiny home Solar System

Wadzanai · Oct 7, 2019

Hie everyone
please assist me with the size of the solar system needed for a small rural home with the following appliances,
1)Laptop 200W/5hrs
2)DVD Home Theatre 150W/5 hrs
3)Decoder 20W/5 hrs
4)LCD TV 100W/5hrz
5)Cellphone 4W/24hrs
6)Solar lightsx12 no idea about Wattage 12hrs

Panel size,inveter size,MPPT controller sizer,Number and type of batteries needed
Potential for upgrade later.

Standby 2 days

Thank you.

Craig · Oct 7, 2019

So it looks as if you need to use 3kw a day

5 hours sunlight 600 watts per hour b
ut need extra always so go for 1kw solar.
Probably want 24 volt system
You will need. 4 10AH batteeies to store that much
A 2000 watt inverter should be fine but think if you may need more for short times for power tools etc

svetz · Oct 7, 2019

Hi Wadzani!

Let me congratulate you on your first post and the excellent organization of the data. You've got a great start and I think a pretty clear idea as to what you want!

Since you're pretty good at this, how about testing the FAQ thread How to figure out how much Solar and inverter wattage is needed to charge a battery and provide feedback on anything that isn't clear. This way you can validate @Craig's post and help a lot of others too!

Wadzanai · Oct 7, 2019

Craig said:
So it looks as if you need to use 3kw a day

5 hours sunlight 600 watts per hour b
ut need extra always so go for 1kw solar.
Probably want 24 volt system
You will need. 4 10AH batteeies to store that much
A 2000 watt inverter should be fine but think if you may need more for short times for power tools etc

Thank you

Wadzanai · Oct 7, 2019

svetz said:
Hi Wadzani!

Let me congratulate you on your first post and the excellent organization of the data. You've got a great start and I think a pretty clear idea as to what you want!

Since you're pretty good at this, how about testing the FAQ thread How to figure out how much Solar and inverter wattage is needed to charge a battery and provide feedback on anything that isn't clear. This way you can validate @Craig's post and help a lot of others too!

Thank you

Wadzanai · Oct 7, 2019

Wadzanai said:
Thank you

This is for Zimbabwe(Southern Africa,Sunlight is plenty from 6am to 6pm everyday for the whole year,except for 2 months where they might be cloud cover on some days but never for 2 consecutive days).In light of this information any need for adjustments on device sizes.

svetz · Oct 7, 2019

Wadzanai said:
This is for Zimbabwe(Southern Africa,Sunlight is plenty from 6am to 6pm everyday for the whole year,except for 2 months where they might be cloud cover on some days but never for 2 consecutive days).In light of this information any need for adjustments on device sizes.

Sadly it doesn't work that way.

At 6 AM the earth's atmosphere is absorbing a lot of the sun. As the sun rises there's less and less atmosphere until solar noon, which is about when you might expect 1000 watts of power per meter squared. So, if you have a 200W panel, that says at 25C if there was 1000 W/m2 of sunshine you'd generate 200 watts. Any time other than solar noon you get less. It's covered in the 2nd post in: How to figure out how much Solar and inverter wattage is needed to charge a battery

What you'll need is the insolation map for Zimbabwe:

So, despite how long the sun is up, if you live in the southern end you might have an insolation of 4.4 (green).

Once you know how many watts per day you need, you can divide by the insolation number to get the watts of the panel size you need. Because of other inefficiencies divide that by .8.

eddie1261 · Oct 7, 2019

@svetz So to understand this correctly, 3kw per day, 3000 watts per day, in the case of a 12v system would be 250 amp hours per day? 3000/12? In his case, a 24v user, 125 amp hours?

This is one place I get lost. When I use my Kill-A-Watt of my Goal Zero to measure consumption, i usually view it in amp hours. With me dealing with a 100ah battery I am constantly reviewing and assessing whether I should buy a second Ruixu 100ah battery. I KNOW 200 amp hours will be plenty for my little trailer. I would SO like to never need shore power. I am really cheap and would hate to pay a campground EVER. I am so cheap that I squeeze a nickel until the buffalo bleeds. I may have to add a wifi repeater to my little hotel room on wheels so I can tap the big box stores from the far end of their parking lots.

To have it clear in my mind, 1200 watt hours is 100 amp hours, right? 1200/12?

Deleted member 783 · Oct 7, 2019

Craig said:
So it looks as if you need to use 3kw a day

5 hours sunlight 600 watts per hour b
ut need extra always so go for 1kw solar.
Probably want 24 volt system
You will need. 4 10AH batteeies to store that much
A 2000 watt inverter should be fine but think if you may need more for short times for power tools etc

Pretty sure he meant 100AH batteries, not 10.

Craig · Oct 7, 2019

New Mexico Will said:
Pretty sure he meant 100AH batteries, not 10.

Yes ty

Craig · Oct 7, 2019

eddie1261 said:
@svetz So to understand this correctly, 3kw per day, 3000 watts per day, in the case of a 12v system would be 250 amp hours per day? 3000/12? In his case, a 24v user, 125 amp hours?

This is one place I get lost. When I use my Kill-A-Watt of my Goal Zero to measure consumption, i usually view it in amp hours. With me dealing with a 100ah battery I am constantly reviewing and assessing whether I should buy a second Ruixu 100ah battery. I KNOW 200 amp hours will be plenty for my little trailer. I would SO like to never need shore power. I am really cheap and would hate to pay a campground EVER. I am so cheap that I squeeze a nickel until the buffalo bleeds. I may have to add a wifi repeater to my little hotel room on wheels so I can tap the big box stores from the far end of their parking lots.

To have it clear in my mind, 1200 watt hours is 100 amp hours, right? 1200/12?

You would be correct.

Also look up juice can wifi antenna they are supposed to have huge directional range.

svetz · Oct 7, 2019

eddie1261 said:
I squeeze a nickel until the buffalo bleeds.

You're scaring me Eddie...they haven't minted nickels with buffalos since the 30's.

Watts = amps x volts, watt-hours = amp hours x volts.

Except the Ah rating listed on a LA battery should actually be listed as 100 Ah@20hr rate. That is there aren't really 100 Ah in LA batteries depending on how they're used and conditions. See http://www.diysolarforum.com/index.php?threads/battery-faq.200/post-1127

Update: Oh, and don't forget to subtract out the round trip inefficiencies (that's post 4 in that thread).

Update 2: Funny you brought up the coin, just so happens Zimbabwe used to have a beautiful water buffalo engraving on the back of a coin. Not sure if they still do or what the amount was.

Wadzanai · Oct 7, 2019

Thanks I actually live in

svetz said:
Sadly it doesn't work that way.

At 6 AM the earth's atmosphere is absorbing a lot of the sun. As the sun rises there's less and less atmosphere until solar noon, which is about when you might expect 1000 watts of power per meter squared. So, if you have a 200W panel, that says at 25C if there was 1000 W/m2 of sunshine you'd generate 200 watts. Any time other than solar noon you get less. It's covered in the 2nd post in: How to figure out how much Solar and inverter wattage is needed to charge a battery

What you'll need is the insolation map for Zimbabwe:

So, despite how long the sun is up, if you live in the southern end you might have an insolation of 4.4 (green).

Once you know how many watts per day you need, you can divide by the insolation number to get the watts of the panel size you need. Because of other inefficiencies divide that by .8.

Bulawayo

eddie1261 · Oct 7, 2019

svetz said:
You're scaring me Eddie...they haven't minted nickels with buffalos since the 30's.

That about covers how old I am.

Except the Ah rating listed on a LA battery should actually be listed as 100 Ah@20hr rate. That is there aren't really 100 Ah in LA batteries depending on how they're used and conditions.

I have a Ruixu lithium, not lead acid. Lithium kind of flies in the face of the "cheap" thing, I know, but I wanted a battery that I can put there and forget about for 8 years. Depending on how much I use the trailer I may order a 2nd matching battery just because I can.

b.james · Oct 7, 2019

Wadzanai said:
Thanks I actually live in Bulawayo

Been there . Take in the rainy season in your sun calculations people say. Well not there . If you are going out in the rainy season you only need take an umbrella if you will be out after 4pm . Monsoonal conditions .
Solar is pretty well over by then too!

Wadzanai I run all that , not all at once , on a 200 Ah 24Volt LFP and a 1000 watt inverter with 2 solar panels of 265Watt in parallel. That might be a good starting point for you but double the battery size (maybe three times ) if Lead acid is used

Bluemalibu · Oct 10, 2019

Eddie, to stretch those battery dollars I opted for two of these 400 Ah units...

https://www.amazon.com/gp/product/B07SQ7BJ5X/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&th=1

But you could get their 200 Ah model for $200 less than the B/B's 100 Ah, or the 100 Ah unit for half of it's cost.

Tiny home Solar System

Wadzanai

New Member

Craig

Watts are Watts!

svetz

Works in theory! Practice? That's something else

Wadzanai

New Member

Wadzanai

New Member

Wadzanai

New Member

svetz

Works in theory! Practice? That's something else

eddie1261

Solar Enthusiast

Deleted member 783

Guest

Craig

Watts are Watts!

Craig

Watts are Watts!

svetz

Works in theory! Practice? That's something else

Wadzanai

New Member

eddie1261

Solar Enthusiast

b.james

New Member

Bluemalibu

New Member

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