Solar system for home with intermittent electricity in hot country

[SolarAden]

Need advice on building a solar system for my sisters home in Aden. Electricity is on for 2 hours and off for about 2 hours. Aden is in the South of Yemen, and it is very hot. Solar system would need to power air con.

I know that I would need a load of batteries (49 packs of Nissan leaf possibly),about 4kw of panels, an inverter, bms, equalizer possibly..

Really would appreciate advice

 

[svetz]

Hi SolarAden, welcome to the Forums!

Probably the best place to get started is to peruse the FAQ and to see what others have already done in the show & tell forum.

To get you going, you'll need to first figure out how much power you need (watt-hours). Then you can figure out how many AH of batteries you'll need and how many solar panels. From there just fire away with any questions you have.

 

[BoloMKXXVIII]

Also, try to air condition the smallest space practical and insulate as much as possible. The biggest savings is in the power you don't need to use. Find the most efficient A/C unit available that is the correct size for your space. Ideally, contact the vendor directly, explain your use case, ask for expected power requirements.

 

[FilterGuy]

Solar system would need to power air con.

And

The biggest savings is in the power you don't need to use.

To that end, look into Earth Tubes for cooling. Here are a couple of videos, but a google search on "earth tube cooling" will provide a wealth of knowladge.

Earth tubes require a bit of land and a lot of digging, but if you can do it they are great.

• Zero or minimal power
• Simple and reliable
• built from readily available parts (this may be a big deal in Yeman)
• Depending on labor costs, they can be cheap.

 

[FilterGuy]

> Need advice on building a solar system for my sisters home in Aden.
The best way to learn is to start watching Wills Videos. (Search YouTube for DIY Solar with Will Prowse. ). He has a LOT of videos covering various aspects of solar and Video. If you hit something you don't understand, see if you can find a video that covers it or ask questions on the forum.

> To get you going, you'll need to first figure out how much power you need (watt-hours).
Svets is right, knowing the power usage is the first thing in planning a system. Start building a spreadsheet that shows the wattage of everything that is going to be powered and the number of hours each day that it will be used. That gives you the *minimum* your system needs to handle. You will need to add at least two fudge-factors: 1) add at least 10% to cover losses in your equipment and batteries. 2) Add some percentage for growth in needs.

Next you need to decide what to assume for how long your batteries need to handle the load. Hours? Days? Full-off grid? From your description, it sounds like it will be very intermittent so this might get difficult to calculate..... but you will need to make assumptions in order to size your batteries. This will also be important if you plan to charge from the grid in order to reduce your Solar Panel size. I would think the minimum you should plan on is 24 hours. 2 Days would be better. If you can afford it, the safest bet is to plan for full off-grid.

> (49 packs of Nissan leaf possibly)
Before you go that rout, please review Will's Video on his evolving opinion on using Tesla Batteries. Everything he says about the Tesla issues would apply to Nissan)

Once you have the system sizing figured out, draw up what you think you will need and post it here. You will get a lot more input if we are reviewing something specific.

EDIT: Added suggestions for duration assumptions. Changed AC to Grid to avoid confusion with Air Conditioning.

 

[bulrush]

I saw a documentary on a Roman air conditioner that was part of the architecture. At one end of the house they had a black-painted chimney on top of the house about 3 ft tall. It wasn't connected to anything, but to a hole in the roof. The sun heated up the chimney and drew up air from the house (this means you had to close all the windows). Then air vents in the floor of the house, let in cool air which came from long tubes underground. The long underground tubes cooled the air before it entered the house.

But here are some other ideas:

The History of Air Conditioning: How Our Ancestors Stayed Cool

Here are some fun facts about the history of air conditioning and the clever methods our ancestors from past civilizations have used to stayed cool.

aristair.com

There appear to be similar concepts in these videos: https://www.youtube.com/results?search_query=roman+air+cooling

 

[FilterGuy]

I saw a documentary on a Roman air conditioner that was part of the architecture. At one end of the house they had a black-painted chimney on top of the house about 3 ft tall. It wasn't connected to anything, but to a hole in the roof. The sun heated up the chimney and drew up air from the house (this means you had to close all the windows). Then air vents in the floor of the house, let in cool air which came from long tubes underground. The long underground tubes cooled the air before it entered the house.

But here are some other ideas:

The History of Air Conditioning: How Our Ancestors Stayed Cool

Here are some fun facts about the history of air conditioning and the clever methods our ancestors from past civilizations have used to stayed cool.

aristair.com

There appear to be similar concepts in these videos: https://www.youtube.com/results?search_query=roman+air+cooling

Yup, the earth tube idea is not new. We can learn a lot from the 'old ways'. Our modern tech is not always better.

 

[Donald Siegel]

Mini splits can run on 800 watts and cool one small fully enclosed room, so the math is not too hard. My nonprofessional but personal calculations suggest you triple the solar panel wattage to run the AC during the day (2.4k). Double the battery capacity for the number of night watt hours you want. With the grid on at least sometimes you can switch to grid when it’s on and top off the batteries faster than solar will. I get 3 hours of off grid AC with two 200amp 12v gel lead acids, about 5 hours with PV/batteries together delivering 300-400 PV continuous watts in the desert.