Solar in Africa

[juju]

Just a few days ago, I posted my first question here - asking about a personal system for a home in Africa. I also have spent time reading a lot of the entries here regarding the implementation of offgrid solar.

One thing that struck me is that, it seems most of the contributors ( or "helpers" , if you want ) to discussions about implementing solar in Africa don't quite seem to understand the basic premise of why people are looking at PV based solutions. They assume the following:

1. Grid power is mostly available / dependable so always size your system purely as a backup for critical loads. ( or even, potentially, charge your batteries with grid power when available, thus minimizing the investment in array size )
2. load requirements based on the above will be very small - anything creeping beyond a 5kw system is ludicrous.
3. to minimize the size and cost of systems, why not use a genset as a backup to the PV system

The reality is as follows:

1. The problems with the grid makes it almost totally undependable as a power source - availability has become increasingly erratic beyond what you can imagine here in the US. Power being off is now the norm. Even when its available, the quality leaves much to be desired.
2. To solve this, people have already used gensets as a readily available solution. They have become the main source of power in some cases. But it has its downsides. Initial cost, cost of gas to run them and maintenance. Compared to smartly and efficiently sized PV systems, gensets loose out. I recently read an article from the BBC about the noise and pollution levels of gensets running in Lagos, Nigeria on a typical day. Just bad. Imagine the cacophony of rattling gensets all day. People are imagining a shift to a solution to completely replace gensets if possible.
3. Load requirements are 24/7. During the day, when the grid is on the fritz mostly, people still want to power the usual things - homes have wall mounted ac units, refrigeration units and freezers and perhaps kitchen appliances that draw power. Businesses have all sorts of needs - again, ac units for offices or for those in the services business ( hotels ) ac units for guest rooms, office computers to run etc. During the evening, the emphasis is on lighting, refrigeration and something to provide comfort from the stifling heat ( the main reason why the wall mounted ac units were purchased in the first place).

So, you can see, it is very easy to size a system with the above parameters that easily exceed what people expect from a typical home based system here in the States. Ideally, for a typical user considering a PV system in an urban area and some applications in the rural areas ( schools, clinics ect), what is needed is advice on how to smartly configure a system to minimize cost, whilst providing coverage for most of the loads provided and at the times when they are needed. Advice about alternatives to the equipment we use - e.g. if AC units are a must, then what are the best solutions out there ( instead of advising that AC units are a no no ). I am particularly intrigued by users here who seem to have adopted some sort of process to manage the use of PV power during the daylight hours and at night ( e.g running certain appliances only at certain times).

Perhaps, will be great to have a good discussion about this - assuming that you had to run loads with high power requirement like ACs and refrigerators, what will a smartly and optimized system to do so look like? I provide a sample load sizing scenario below as a starting point. Take it apart and lets see the most efficient system you can design for this - maybe this can be a sticky for everyone in this situation.

Ultimately, I suspect for the situation I describe above, the solution may not be just implementing a PV system and managing usage, but rather a much more broader approach to how we build our houses - making them green as much as possible to reduce the dependence on energy sapping appliances. Also, perhaps, with time, advancements in battery tech will remove the restrictive cost of this component in a solar system, making it truly affordable as a cost effective replacement for grid power - not because we want to stick it to anyone or are on some crusade to be offgrid at all costs because it is cool to do so, but purely out of necessity. It is a necessity for us and the advice towards building and optimizing a system should take this into account . Thxxxx

sample load requirement: ( totally made up )

Note that we are on 220V @ 50HZ.

load	quantity	use per day	freq. per week
ac unit	2	6	7
fans	2	4	7
Compact flourecents	15	6	7
TV ( 50+ inches)	1	6	7
desktop pc	1	4	7
laptop	1	4	7
refrigerator	1	6	7
freezer	1	6	7
microwave	1	0.1	7
blender	1	0.1	7
wall plugs	5	2	7
water pump	1	2	7
water heater	1	2	7

[Bucho]

One thing that struck me is that, it seems most of the contributors ( or "helpers" , if you want ) to discussions about implementing solar in Africa don't quite seem to understand the basic premise of why people are looking at PV based solutions.

Well I've noticed that this place can have a JUST DRINK THE KOOLAID!!! sort of vibe at times but there's also the issue that how many people here are familiar with doing solar in Africa? To a certain extent people can only tell you what they know *shrug*

[thastinger]

For your above scenario, you're looking at an initial system cost of over 80,000 USD. In less than 10 years, you'll get to replace a 4 ton battery bank. I get that the grid is unreliable in 3rd world countries that's part of the reason they aren't first world countries, but I could suffer through a lot of interruptions for that kind of money.

FWIW, I've noticed lately that people want to go off-grid but they have no interest in changing their consumption habits, then get defensive when you tell them what the cost is to get what they want.

[juju]

For your above scenario, you're looking at an initial system cost of over 80,000 USD. In less than 10 years, you'll get to replace a 4 ton battery bank. I get that the grid is unreliable in 3rd world countries that's part of the reason they aren't first world countries, but I could suffer through a lot of interruptions for that kind of money.

FWIW, I've noticed lately that people want to go off-grid but they have no interest in changing their consumption habits, then get defensive when you tell them what the cost is to get what they want.

Its not about a reluctance to change consumption habits or getting defensive - its about looking for practical solutions. For instance, looking critically at that load list, is that really different than the load consumption of an average home here in the US? ( so I can compare to the price of solar systems here ). Homes that are now being served by the likes of Solarcity with systems that go quite a bit of ways to cover a large portion of the home's energy needs ( but not all ) with about 5kW systems - and certainly not in the 80K price range. In Europe, its even half the US cost due to much lower BOS costs. ( granted some of these systems are grid tied with no batteries.) But, Solarcity has recently started leasing out Tesla batteries as well and the price even for a 5kw system with batteries is not in the 80K range.

If this list is that far out there, then what types of coverage ( types of appliances and hours of use ) do you get for something like a 5kW system here in the US? Take out the AC and the freezers from that list and what else is left?

So looking at that list, what size system will support it? Something over 10kW? thats a mini power station.

[Bala]

Its not about a reluctance to change consumption habits or getting defensive - its about looking for practical solutions. For instance, looking critically at that load list, is that really different than the load consumption of an average home here in the US? ( so I can compare to the price of solar systems here ).

Homes that are now being served by the likes of Solarcity with systems that go quite a bit of ways to cover a large portion of the home's energy needs ( but not all ) with about 5kW systems

- and certainly not in the 80K price range. In Europe, its even half that cost due to much lower BOS costs. ( granted some of these systems are grid tied with no batteries. But, Solarcity has recently started leasing out Tesla batteries as well and the price even for a 5kw system with batteries is not in the 80K range.

If this list is that far out there, then what types of coverage ( types of appliances and hours of use ) do you get for something like a 5kW system here in the US? Take out the AC and the freezers from that list and what else is left?

I have lived off grid for 9 years. it is important to remember that living off grid is a different lifestyle, those who do it and get good battery bank life "live off grid" they dont just have off grid power. They closely monitor there power all the time.

What I have highlighted in your text is meaningless, that system could quite well run the home, but you need to know what life they got from the battery bank before you can say it works.

without autostart genest backup it would be reasonable to expect that they may kill the batteries in less than one year.

For all but the experienced conscientious off grid person a/c without auto start genset back up is basically out of the question.

[paulcheung]

The typical US household use around 1200 to 2000KWH per month, their electricity bill is around 150 to 250 US dollars per month as their electricity is very cheap. The solar system they use are mostly grid tie system, so they don't have any limitations. With off grid the battery is the biggest problem in cost and maintenance.

[Sunking]

J

Note that we are on 220V @ 50HZ.

load	quantity	use per day	freq. per week
ac unit	2	6	7
fans	2	4	7
Compact flourecents	15	6	7
TV ( 50+ inches)	1	6	7
desktop pc	1	4	7
laptop	1	4	7
refrigerator	1	6	7
freezer	1	6	7
microwave	1	0.1	7
blender	1	0.1	7
wall plugs	5	2	7
water pump	1	2	7
water heater	1	2	7

Operating 220 @ 50 Hz does not change a thing. To take all this off-grid will cost as much as a house. Half of that cost will be batteries you replace every 5 years. Being in SA does not change any of the facts. Just to run the Air Conditioning will cost you $40K initially and $20K every 5 years in battery replacement. You need to learn to either live without most of that stuff, or move.

[Willy T]

Here are a couple Quote's from a large system owner that is totally off grid. While he lives in Minnesota there would be some trade off with A/C and his heat. He is not the only one, but he's trying to run a modern home on solar with all the comforts. You can see the direction he's heading.

Well, I've been busy here. Like I said, I got new projects going that is outside the scope of "renewable energy" forums, so have little time to participate. When our present battery bank wears out we will not be buying another one. I've designed and built a dual redundant, failover co-generation CHP setup using 900 rpm diesel power that will be replacing our present system this coming summer. I can put the entire system in for less money than what it will cost to replace our present batteries in a few years. I have the first unit built and tested and sitting in my shop. It has a Cummins 4BT power unit. The units are 25 kVA prime, each. I'm building a second unit for redundancy and peaking - have it about half done right now and trying to get it done before spring. It took me 2 1/2 months to build the first one. I'm hoping to have the second one done by April so we can fire up the excavator in the spring and start construction on our new power plant.

The XW inverter is "smart" enough, has AC coupling capability, and has good enough controls and monitoring to be able to use it as the "grid" and "brains" for the system to tell the Cummins Power Command system how to control and sync the CHP units. We will have full 200A service to both our house and my shop when I get it done.

Our new system will eliminate having to burn wood for primary heat, provide us with virtually unlimited power with totally automatic control, used staged generators to cut fuel burn when only one is needed, and eliminate the expense and headache of batteries. Sure, it's not really "going green". But I could care less about "going green" except when it comes to saving green on off-grid power costs. And the type of system I have designed is in common use in remote Alaska villages and South Pole Station in Anarctica for many, many years. The US becoming the largest oil producer on earth pretty much made so-called "going green" obsolete as far as I'm concerned.

Not been here in awhile - been busy with other stuff. But seen this thread and wanted to inject some info.

The reason our system works, and we can have an all-electric off-grid home is because we use a peaking generator and extensive use of wind power in the winter time (7.5 kW Bergey Excel-R which we put in two years ago). That turbine can easily produce 60 kWh/day at moderate wind speeds in the winter when it's needed most. We actually have a fairly small battery bank for a 25-30 kWh/day off-grid home at only 1156ah. But, when high-draw loads come on so the inverter is operating in overload it starts the genset and shifts the load from the inverter to the generator. We use a quite small 4.0 kVA genset, the inverter is sine wave sync'd on both phases (split-phase power) with the genset, so the genset carries the first 4.0 kVA of the load and the inverter carries the rest. This takes the load off the battery bank so Puekert Effect don't sack the bank out and we keep the discharge rate at reasonable levels at peak load. And saves on fuel because we don't need a 10 kW genset to support a 10 kW load when the generator is operating. And saves on inverters because we don't need stacked inverters to carry 10 kW intermittent loads. And saves on batteries because we don't need a big battery bank to support stacked inverters. And saves on solar panels and wind turbines because we don't need a bunch of controllers and extra expense to properly charge a big battery bank.

Sure, it means burning generator fuel to support loads over 6 kW. But for us, big deal. Off-grid living is not cheap in the first place and we're not short on money. So a $150/month generator fuel bill for 5 months of the year to support our peak loads is not a big deal for us.

And yes, our system is grossly over-sized for the summer months and we run central A/C in our house just to use it up. BUT - the generator is still used in summer too to support peak loads at times. Just our peak loads are higher in winter than in summer because in winter my wife uses the electric clothes dryer, for instance, where in summer she uses the clothes line. And we cook outside on the grille in summer instead of using the electric range in the kitchen. As a couple examples. It's 20 below zero here in the winter time, so that also means the gensets are preheated 24 hours a day for when they're needed - more power consumption. The days are short, so that means longer hours inside running lights, and more time spent in my shop using lots of power. And on and on.

So I designed our system to use the smallest battery bank that is feasible, and use generators to support it when otherwise more inverters and batteries would be needed. Batteries are most expensive thing for off-grid power. Not generators. Generators are cheap (in the off-grid world). None of it is cheap compared to the world of utility power. While we live here off-grid for the last 15 years at about what it would cost for someone to live in California on peak power rates, that is only out-of-pocket expense. We got close to $100 Grand invested in the equipment, wiring, controls, monitoring and misc to produce that power. And that's what makes off-grid power expensive because all that equipment has to be maintained, eventually replaced or upgraded. I put the pencil to it and figured out that we can buy like 6 generators and run a pipeline from the Bakken Oil Field to fuel 'em for less than what a battery bank costs.

[Bucho]

Its not about a reluctance to change consumption habits or getting defensive - its about looking for practical solutions. For instance, looking critically at that load list, is that really different than the load consumption of an average home here in the US?

The most practical solution out there is to use less power than the average home in the US. Because unless these systems are for diamond mine owners the cost of powering the average home in the US becomes untenable off grid.

Out of curiosity have you looked at hybrid systems?

[pleppik]

Perhaps, will be great to have a good discussion about this - assuming that you had to run loads with high power requirement like ACs and refrigerators, what will a smartly and optimized system to do so look like? I provide a sample load sizing scenario below as a starting point. Take it apart and lets see the most efficient system you can design for this - maybe this can be a sticky for everyone in this situation.

First, I'm not an expert in off-grid living so take everything I write with a grain of salt. But I think I may have gleaned a thing or two from the actual experts on this forum, not all of whom are terribly polite or patient to newbies.

So taking your statement that the grid really isn't a viable option, and you're trying to get away from using gas generators (IMHO, a good move, since fuel and maintenance for a generator may be one of the few sources of power more expensive per kWh than batteries), here's how I would approach this problem....

The thing to keep in mind with off-grid solar is that this isn't really about solar. It's about batteries. The batteries will be the most expensive part of the system, require the most maintenance, and need replacing the most often. The solar panels are just a convenient and inexpensive way to charge the batteries (plus generate some power to use at the same time). Maybe in a decade or two the battery technology will improve so as to be cheaper and less fussy, but that's not what we have to work with today.

So I would take all the loads and categorize them as follows:

1. Stuff which must run at night. Lights, for example.
2. Stuff which could run either day or night, as needed. Like computers, refrigerators, A/C, etc.
3. Stuff which you can run when it's convenient. Vacuum cleaners, copy machines, and the like.
4. Stuff you can use to soak up extra power to be useful some other time, like water heaters.

Loads in lower-numbered categories will be more expensive to run, since they will be more likely to have to run off batteries and not during the daytime when the sun is out.

So the next step is to go through your loads and see what you can move to a higher-numbered category. For example, can you get a super-insulated freezer and put it on a timer so it only runs during the daytime? Can you run the A/C only when the sun is out and shut it off during the night? You are essentially engineering your lifestyle to cut battery usage to the bare minimum, because anything you run off batteries will the 10x as expensive to power as something which can be run off the solar panels.

Now that you've figure out what you want to run (and just as important, what you want to run off batteries) you need to figure out exactly how much power this will take. Ideally, hook up a power meter like a Kill-a-Watt for a few days to see just how much power that refrigerator uses. It's worth spending more to buy super-efficient appliances, since they will require a lot less battery.

So at the end of all this you should know (a) how many kWh per day you need, (b) how much of that must come from batteries and how much can come directly from the solar, and so (c) how much battery capacity you need, planning for stretches of cloudy weather. This is what you need to know in order to actually design your system.

Once you know all this, there's lots of good advice elsewhere on this forum about how to size a battery bank for a given demand, how to size the solar panels for your needs, and how to manage both. You will still need a generator, but it will only need to run when you have a few days of cloudy weather, so it won't be nearly as expensive as what you're currently experiencing.

I hope this helps.

[SunEagle]

First, I'm not an expert in off-grid living so take everything I write with a grain of salt. But I think I may have gleaned a thing or two from the actual experts on this forum, not all of whom are terribly polite or patient to newbies.

So taking your statement that the grid really isn't a viable option, and you're trying to get away from using gas generators (IMHO, a good move, since fuel and maintenance for a generator may be one of the few sources of power more expensive per kWh than batteries), here's how I would approach this problem....

The thing to keep in mind with off-grid solar is that this isn't really about solar. It's about batteries. The batteries will be the most expensive part of the system, require the most maintenance, and need replacing the most often. The solar panels are just a convenient and inexpensive way to charge the batteries (plus generate some power to use at the same time). Maybe in a decade or two the battery technology will improve so as to be cheaper and less fussy, but that's not what we have to work with today.

So I would take all the loads and categorize them as follows:

1. Stuff which must run at night. Lights, for example.
2. Stuff which could run either day or night, as needed. Like computers, refrigerators, A/C, etc.
3. Stuff which you can run when it's convenient. Vacuum cleaners, copy machines, and the like.
4. Stuff you can use to soak up extra power to be useful some other time, like water heaters.

Loads in lower-numbered categories will be more expensive to run, since they will be more likely to have to run off batteries and not during the daytime when the sun is out.

So the next step is to go through your loads and see what you can move to a higher-numbered category. For example, can you get a super-insulated freezer and put it on a timer so it only runs during the daytime? Can you run the A/C only when the sun is out and shut it off during the night? You are essentially engineering your lifestyle to cut battery usage to the bare minimum, because anything you run off batteries will the 10x as expensive to power as something which can be run off the solar panels.

Now that you've figure out what you want to run (and just as important, what you want to run off batteries) you need to figure out exactly how much power this will take. Ideally, hook up a power meter like a Kill-a-Watt for a few days to see just how much power that refrigerator uses. It's worth spending more to buy super-efficient appliances, since they will require a lot less battery.

So at the end of all this you should know (a) how many kWh per day you need, (b) how much of that must come from batteries and how much can come directly from the solar, and so (c) how much battery capacity you need, planning for stretches of cloudy weather. This is what you need to know in order to actually design your system.

Once you know all this, there's lots of good advice elsewhere on this forum about how to size a battery bank for a given demand, how to size the solar panels for your needs, and how to manage both. You will still need a generator, but it will only need to run when you have a few days of cloudy weather, so it won't be nearly as expensive as what you're currently experiencing.

I hope this helps.

+1. That is good advice. I hope the OP listens and understands why a solar battery system can initially cost that much.

[thastinger]

Its not about a reluctance to change consumption habits or getting defensive - its about looking for practical solutions. For instance, looking critically at that load list, is that really different than the load consumption of an average home here in the US? ( so I can compare to the price of solar systems here ). Homes that are now being served by the likes of Solarcity with systems that go quite a bit of ways to cover a large portion of the home's energy needs ( but not all ) with about 5kW systems - and certainly not in the 80K price range. In Europe, its even half the US cost due to much lower BOS costs. ( granted some of these systems are grid tied with no batteries.) But, Solarcity has recently started leasing out Tesla batteries as well and the price even for a 5kw system with batteries is not in the 80K range.

If this list is that far out there, then what types of coverage ( types of appliances and hours of use ) do you get for something like a 5kW system here in the US? Take out the AC and the freezers from that list and what else is left?

So looking at that list, what size system will support it? Something over 10kW? thats a mini power station.

WTF are you talking about? You go from totally off grid battery, to hybrid, to grid tie. Do you understand the differences in those systems? 80K for 50Kwh/day is accurate for an off grid battery system, which is what you were originally talking about. Grid tie would be much less expensive but it doesn't solve your unreliable grid problem. There are no revelations to be had here unless you're developing a new technology, it costs what it costs.

[DanKegel]

So the next step is to go through your loads and see what you can move to a higher-numbered category. For example, can you get a super-insulated freezer and put it on a timer so it only runs during the daytime? Can you run the A/C only when the sun is out and shut it off during the night? You are essentially engineering your lifestyle to cut battery usage to the bare minimum, because anything you run off batteries will the 10x as expensive to power as something which can be run off the solar panels.

Now that you've figure out what you want to run (and just as important, what you want to run off batteries) you need to figure out exactly how much power this will take. Ideally, hook up a power meter like a Kill-a-Watt for a few days to see just how much power that refrigerator uses. It's worth spending more to buy super-efficient appliances, since they will require a lot less battery.

So at the end of all this you should know (a) how many kWh per day you need, (b) how much of that must come from batteries and how much can come directly from the solar, and so (c) how much battery capacity you need, planning for stretches of cloudy weather. This is what you need to know in order to actually design your system.

Yeah. And maybe an iterative approach - where you design a system that
*only* handles LED lights first, and make that work well before going on to
the next low-energy-but-pressing need. See for instance what M-Power is doing,

http://www.csmonitor.com/World/Africa/2015/0125/Africa-s-quiet-solar-revolution

So: total rethink. Solar power is not a 1:1 replacement for grid power. Throw
away your assumptions, ignore installed equipment (ok, I'm dreaming here),
and address only the most pressing need of people who have never had power.

And then in a few years, that approach may tiptoe into the middle class
levels of comfort you were originally talking about.

Does that make sense? Sitting here in my palatial estate in Los Angeles ,
it seems wise, but I have no idea how it sounds in Africa.

[juju]

+1. That is good advice. I hope the OP listens and understands why a solar battery system can initially cost that much.

@pleppik 's advice is the kind of input I was looking for - how users here are managing or balancing loads for an entire house when the grid is unreliable or non existent. Much appreciated.

I totally get how batteries completely changes the calculus. My post is not about that and its unfortunate some here are getting prickly about driving that fact into my newbie head. I was hoping to tap into the years of experience here to learn about how users with the same kinds of load requirements have managed, given the special restrictions of lack of reliability of the grid or lack thereof. I totally appreciate the depth of knowledge here so lets keep this constructive like @pleppik has done.

[juju]

http://www.csmonitor.com/World/Africa/2015/0125/Africa-s-quiet-solar-revolution[/url]

So: total rethink. Solar power is not a 1:1 replacement for grid power. Throw
away your assumptions, ignore installed equipment (ok, I'm dreaming here),
and address only the most pressing need of people who have never had power.

And then in a few years, that approach may tiptoe into the middle class
levels of comfort you were originally talking about.

Does that make sense? Sitting here in my palatial estate in Los Angeles ,
it seems wise, but I have no idea how it sounds in Africa.

Sure it does - MPower's system is a pay as you go system for rural areas, I think. I am looking at needs that extend beyond that - perhaps homes whose usage profile is similar to an average home here as well as businesses - who are most impacted by this. For businesses, their usage profile even extends beyond what I specced out here. One bank for instance, has been running large diesel powered generators for each of its branches. it is hoping to supplement or completely replace that due to running costs. i hope this helps clarify the intent of my question here. Much appreciated.