The grid sucks in rural Madagascar. What do I need?

[Dorosa]

I'm new here, and pretty new to solar. If there's a better place for this thread, let me know.

I'm living in rural Madagascar with my wife and kids. We live 15 hours away from the supermarkets/grocery stores, so when we go to "town" every couple months, we load up the pickup with stuff we can't get locally, and then freeze it (sliced bread, cookies, sauces, frozen stuff, etc) and we also buy local meat and chicken locally when it's available at the quality we prefer, and freeze that too.




We have grid power most of the time, but we experience daily voltage drops (instead of 220v, it drops to ~150/160v for an hour or so), and frequent blackouts (sometimes it's every night from 8pm-8am for a month at a time).

I have a 12v 75w fridge that we have been using to keep things preserved when there are power outages. But the system I have hooked up is obviously not sufficient, or not efficient, because the fridge routinely doesn't make it through the night.

I also want to buy a 12v deep freezer, which I can get "in town".

Locally, all I can get are probably the cheapest solar panels available, and only cheap PWM 30A controllers, and only lead acid batteries. Everything is Chinese.

I currently have 3x 120w panels hooked up in parallel to a 30A controller, which is then hooked up to 2x 150aH batteries. I also have a 200aH sealed non-lithium battery, which I assume would be gel? I hooked this up with very little research. I just bought what I could find before the last cyclone came through (which shuts down the grid for a month or so) and hooked it up to have something, at least during the day, to charge stuff, and run the fridge.




After some more research, it appears my array is woefully underpowered for the battery bank, so I'm probably never charging it all the way and it's being drained to empty every night.

So my latest plan is to bump up my solar array. Locally I can source more panels and more 30A PWM controllers.

This is what I'm considering putting together.

What do you guys think? (blue is what I already have, red is what I would need to buy)



I also have a 0.75kw deep well pump to fill our water tank and a 1kw pressure pump to pump water from the tank into the house. I would love to be able to hook them up to the solar system if possible. Otherwise, I'll just be getting a small 3000w gas generator for the times the power is out but we want to take showers, etc.

 

[rin67630]

but we want to take showers,

in Madagascar you wont need high tech to take warm showers from solar. A bucket does the job....

 

[DIYrich]

Consider adding a grid powered battery charger. It will be a backup to your solar.

 

[Dorosa]

in Madagascar you wont need high tech to take warm showers from solar. A bucket does the job....

Oh, we've done the bucket shower thing. We prefer pressurized hot water from a showerhead. Haha

We are living out here but we have no intention of roughing it more than circumstances require. I'm hoping to make sure my circumstances allow our preferred way of life as much as possible.

 

[SamDeleted]

Consider adding a grid powered battery charger. It will be a backup to your solar.

This is a good point, in a situation like OP I would keep the grid power charging the batteries continuously (when available)

Only dropping to battery when needed

 

[lexio]

This is a good point, in a situation like OP I would keep the grid powder charging the batteries continuously (when available)

Only dropping to battery when needed

just go with a all in one if you can get it there. lived in Kenya for a while for hot water just put a long black tube on the roof it is also working. else built your self a solar boiler they are not difficult to built.

 

[SamDeleted]

Oh, we've done the bucket shower thing. We prefer pressurized hot water from a showerhead. Haha

You could heat the water in the sun and then pressurise with a 12v pump when you want to shower. This would use a LOT less power



Could do a black IBC in the sun and a 12v pressure pump like a 'Shurflow' (similar pump cheaper models are available from china)

Shurflo Trail King 10L 30PSI Water Pump - 2095-403-443 - Caravan Motorhome Boat | eBay

The Trail King 10 has a robust die cast alloy lower housing with twin ball bearing driveand are very quiet when in operation. Automatic triple diaphragm pump with integral pressure switch to ensure a smooth water flow.

www.ebay.co.uk

 

[SamDeleted]

just go with a all in one if you can get it there. lived in Kenya for a while for hot water just put a long black tube on the roof it is also working. else built your self a solar boiler they are not difficult to built.

Yea absolutely, DIY solar hot water is EASY . I bet it's even easier in Africa with all that sun !

 

[lexio]

Yea absolutely, DIY solar hot water is EASY . I bet it's even easier in Africa with all that sun !

yea no freezing water so you don't need a heat ex changer just a couple of pipes welded a black back panel and a piece of glass above it
and a isolated water tank.
Need to dig in the photos to see if i have a picture of the one i have built
you need to watch out almost els your water tank of 100 liter starts cooking

 

[SamDeleted]

Need to dig in the photos to see if i have a picture of the one i have built
you need to watch out almost els your water tank of 100 liter starts cooking

Pics appreciated ?

 

[Dorosa]

Guys, I have hot water at the moment with 4 bar pressure. Life is good. Until we have a cyclone or just general power outages, and then it's back to buckets. It was an afterthought that i would like to be able to hook the pumps up to the solar system if that was possible. Anyway, let's just take water off the table.

And yes, grid power for charging batteries is great. Until there's no grid power for a month. Which of the scenario I'm trying to plan for.

Does anyone have any input on the solar aspect of my post?

 

[SamDeleted]

Does anyone have any input on the solar aspect of my post?

Sorry about that lol!

You seem to have it pretty well figured out .. the question is will you have enough solar to cover your loads

So for that we need to know two things

A) estimated solar production
https://pvwatts.nrel.gov/ (calculator)

B) real world energy consumption of the loads (fridge/freezer... In watt/hrs )


With these two we will be able to do the maths, see if you'll have enough solar panels

 

[Dorosa]

Sorry about that lol!

You seem to have it pretty well figured out .. the question is will you have enough solar to cover your loads

So for that we need to know two things

A) estimated solar production
https://pvwatts.nrel.gov/ (calculator)

B) real world energy consumption of the loads (fridge/freezer... In watt/hrs )


With these two we will be able to do the maths, see if you'll have enough solar panels

Thanks. When i did the solar production for my area, it came out to 169kw per year for each 120w panel in my current array - avg 463w per day, or 38amps per day.
The consumption from a 75w fridge and a 55w freezer whose compressors run maybe 18 hours per day is, according to my calculations, about 150 and 100 aH per day, which puts my existing battery bank right where it needs to be to handle each of them without going below 50%.

I assume, especially since I'm limited to pwm controllers and have to use several separate strings of panels anyway, that its better to keep each load's battery and solar panel array independent instead of trying to connect my 2 150aH batteries and 1 200aH gel battery in parallel for a 12v 500aH battery bank.

I do have the 2 150aH batteries set up in parallel for a 12v 300aH battery, which i plan to charge with a second 300-360w string of panels via a second 30a pwm controller.

If my math and thought process on this is good, then I'll just proceed with this setup.

In that case, can someone please help me better understand how to integrate fuses or DC circuit breakers into this model?

Between panel and controller, then between controller and load? So i need breakers or fuses between controller and battery? What size?

I see on my panels that there's a short circuit rating, and i understand that the fuse should be 1.57 that number? What if there are 3 of those panels wired in parallel?

For the others, would it be 1.25x the 30a rating if the controller?

I honestly don't know what i don't know about breakers and fuses.

Thanks guys!

 

[houseofancients]

Oh, we've done the bucket shower thing. We prefer pressurized hot water from a showerhead. Haha

We are living out here but we have no intention of roughing it more than circumstances require. I'm hoping to make sure my circumstances allow our preferred way of life as much as possible.

Wouldnt be looking for pv for hot water; solar water heating much more efficiënte, and will require much less of a Investment in the pv side of things

 

[Quattrohead]

I think you need to get yourself some good larger panels new or used and a good MPPT/AIO type unit.
Having 2-4kw of panels will cover shitty batteries for a very long time. Worth saving up for or risking the shipping to get them I would say.

 

[SamDeleted]

that its better to keep each load's battery and solar panel array independent instead of trying to connect my 2 150aH batteries and 1 200aH gel battery in parallel for a 12v 500aH battery bank.

Yes correct, keep them separate

If my math and thought process on this is good, then I'll just proceed with this setup.

Your maths is good , BUT what happens if there is a cloudy day (does this happen in Madagascar??)



A lot of people size their batteries to cover the load for 3 days total , not 1 ...

In that case, can someone please help me better understand how to integrate fuses or DC circuit breakers into this model?

Between panel and controller, then between controller and load? So i need breakers or fuses between controller and battery? What size?

I see on my panels that there's a short circuit rating, and i understand that the fuse should be 1.57 that number? What if there are 3 of those panels wired in parallel?

For the others, would it be 1.25x the 30a rating if the controller?

I honestly don't know what i don't know about breakers and fuses.

Fuses are simple once you understand. Do not worry about breakers, they are more expensive and no safer than proper fuses

Again you are correct. In your case you'll need two fuses per system:
Mppt > battery
Battery > load





1.25x is the correct figure, 30amp controller x 1.25 = 37.5amps ... So I would say a 40a or 50a fuse is appropriate.... You just need to ensure the cable you're fusing has an amp rating above your fuse size

Example:.. 10mm2 cable is rated for up to 75amps so that would be more than big enough

 

[SamDeleted]

I see on my panels that there's a short circuit rating, and i understand that the fuse should be 1.57 that number? What if there are 3 of those panels wired in parallel?

Solar panel > MPPT

This cable only needs fusing if you have more than 2 solar panels parallel

The solar panel label often have the max fuse rating, this one is 15amp max fuse

 

[Dorosa]

I think you need to get yourself some good larger panels new or used and a good MPPT/AIO type unit.
Having 2-4kw of panels will cover shitty batteries for a very long time. Worth saving up for or risking the shipping to get them I would say.

There are no mppt units that i can find around here.

And there's no online shopping/ordering. There's what you can find in some dingy little shop that sells random hardware, electronics, and beer.

Like we say with our 6 year old constantly, "you get what you get in madagascar."

 

[Dorosa]

That's a great observation!

Yes correct, keep them separate



Your maths is good , BUT what happens if there is a cloudy day (does this happen in Madagascar??)



A lot of people size their batteries to cover the load for 3 days total , not 1 ...





Fuses are simple once you understand. Do not worry about breakers, they are more expensive and no safer than proper fuses

Again you are correct. In your case you'll need two fuses per system:
Mppt > battery
Battery > load





1.25x is the correct figure, 30amp controller x 1.25 = 37.5amps ... So I would say a 40a or 50a fuse is appropriate.... You just need to ensure the cable you're fusing has an amp rating above your fuse size

Example:.. 10mm2 cable is rated for up to 75amps so that would be more than big enough

That's a great observation about the amount of days the battery should be able to cover.

 

[Quattrohead]

Are you sure you can't get someone like sungoldpower to ship panels and inverters to you? The Chinese will ship anything to anywhere if you give them dollars LOL