diy solar

diy solar

New to solar and having a couple of questions

Mark_almelo

New Member
Joined
Jun 2, 2022
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5
Hello,

my name is mark and I’m in the beginning of planning and building a house in west-Africa. I’m by no means a-technical and experience in a lot of things but when it comes to electricity I’m only experienced in 12v systems and your ordinary household 230v system (but not so far as installing a complete fusebox)

my head is spinning of the loads of information I get on internet and also “experts” over here (but it’s a country we’re they will tell and do anything to make a sale, so it’s questionable)

at this point I’m not yet really interested how many panels I need or how many batteries. But it’s got more to do with the inverter and how to set everything up and connect it. I heard that a lot of batteries only have a lifespan over here of about 3 years, and that it got mostly to do because people discharge the batteries completely and that the lifespan will expand drastically when you don’t let it get under 50%. Is that true or is it just the poor quality that they sell over here? (I have the possibility to buy it in Europe and ship it over)

so I was thinking and trying to search because I thought I couldn’t possibly be the only one with these problems, is there something like a smart inverter or an “add-on” that automatically monitors the batteries and will shut the power of when it gets below 50%? or even more smart dat it can even shut of certain circuits of the house at a certain percantage (60% for example) so only the essentials are left like lights and the fans)

there is a national grid system, but it’s really unreliable. Is it possible to wire it in to the inverter? For example in the rainy season that the inverter can detect that todays weather (information collected by internet forecast for example) and sun is not good enough to charge the batteries by solar and if there is power on the grid it will fill up the batteries from there? (During the day I mean so I’ll have power in the evening and night if the grid is off)

like I said im completley new to this and maybe I’m being stupid but these are questions that pop in my mind. Surely considering how smart appliances are becoming. In europe my Honeywell thermostat even knows what expected time I’m coming home or leaving home and adjust the temp for it, it’s not that impossible to think a solar system can be that smart right?


its probably not going to be a massive system, here are some appliances on the top of my head that will be needed. It’s going to be livingroom/2 bedrooms/2bathrooms/pantry/porch

- 2 fridges
- 1 freezer
- led lighting spots for the house and garden
- 2 TV’s
- washingmachine / dryer (but I’m okay with wiring that into the national grid and not on solar)
- boiler (but may also go the route of solar heating)
- small items like charging your phone / ipad / router etc.
- pump for the borehole
- pump for the swimmingpool (but also okay with wiring into national grid)
- fans for livingroom, bedrooms and porch
- in rare occasions kitchen appliances like a waterheater / toaster ect
- eventually if possible 2 AC’s


i get there are still a lot of it’s and but‘s but i will have to start somewhere right?
 
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Well, I'll start the default answer to these questions and we can work from there. Here's you To-Do list:

1: Power audit! This will give you some important information on how big your inverter needs to be as well as how much battery capacity you'll need. There is a link in the FAQ section (I think, or someone here will post it shortly) so fill in the blanks and see what it comes up with. You'll probably need some sort of Kill-A-Watt to get accurate measurements. Are you going to be running a 12v system? 24v system? 48v system? What are the specs on your solar panels? VoC? Vmp? Being as this is a new build, throw together a wish list of what you want and estimate on the high side.

1a: Where do you live? Speccing out a system for Scotland is a LOT different numbers than Arizona due to the amount of light you actually get. Someone here can post the link to the PVwatts.com or JCR Solar Uber-Sun-Hours calculator sites to help figure out how much you'll have to work with. That will be a box in the Power Audit form.

2: Parts list: You don't need a make & model list, just a parts list to start from for reference. You'll need an inverter, a MPPT charge controller, fuses, shunt, buck converter, batteries, wire, etc. Once you have a basic list it can be fine tuned to make & models after that. If you're looking at the All-In-Ones check for correct voltage outputs (120v or 240v Split Phase for North America, 220v Single Phase for European type areas) and make sure it has enough capacity for a little bit of growth and fudge factor.

3: Budget!: Steak is great but doesn't mean anything if your wallet says hamburger. :) Figure out what you're able to spend now vs what you'll have to cheap out on now and upgrade later.

4: Tape measure! Figure out where you're going to stick all the stuff you'll need. A dozen 3000AH batteries sounds great until you're sleeping on the floor because there's no room left for a bed. Is there a compartment that can house all this stuff? Will the server rack batteries fit? Are you going to have to make space? Physics can be pretty unforgiving.

5: Pencil out what you think you need and throw it at us so we can tell you what you've missed (because we ALL miss stuff the first go-round :) ) and help figure out which parts and pieces you're going to want to get.
 
Lead-acid batteries will die in a few months or years if over-discharged, or if not fully charged. System needs to be designed to disconnect when low, to charge properly, and needs enough power production.

Lithium (several chemistries) die if over-charged or over-discharged, but can sit in between. Some varieties are more likely to fail from a single abuse (over charge/discharge), or to catch fire.

Neither kind of battery really likes excessively hot weather.

Systems can be built to power what you have, and to serve as backup to grid. Less expensive if limited things (e.g. refrigerators) are powered during grid failure.
Prices range from < $1000 for something small in a van/camper to > $50,000 powering large house. Batteries are often the majority of the cost. A power audit will show how much you need and help you decide what to leave unpowered.

There are some companies with a presence, installers and support, everywhere. Like SMA. Some brands, you wouldn't have anyone available who understand them. Most of us design and install our own systems, diagnose failures to the box and replace or send in for warranty. Unless you learn to do that, you need support of a company that can.

My system is grid-tied, has large amount of PV panels and SMA inverters, small battery. Most of the time it acts as a UPS. During power failure, I have enough to run A/C during the day, but at night only minor loads. We have "net metering" so when grid is up, PV backfeeds through the meter, recording credit for use other times, so what I bought produces the power I use daily, not just as backup.
 
1: have no idea, haven’t bought or scavenged a single piece of equipment yet, so I’ll i have to go is from my “wishlist of appliances”. Don’t know what system. Like I said I’m an open book so what system is best for me? read something that 48v systems can handle more watts at a single time. So I’m thinking 48v? Don’t have any solar panels and don’t know what’s available over here yet (but keep in mind, almost everything that’s sold here is chinesium and is the cheapest of the cheapest crap)

1a: the house is going to be in Sub Saharan west Africa, 9 months out of the year sun sun sun but 3 months rainy and can get really cloudy.

2: again have no idea what I want to use, that’s why I’m over here for advice, does a system like i mentioned even exist? It’s 220v European type (at least all European appliances work over here) capacity I understand but I don’t know how much my system is going to need in the first place.

3: I have no idea what my budget is going to be. What do you recommend for a setup that I need that’s good but budget friendly?

4: more then enough space (haven’t started the building of the house yet so I can make the storage as big as I want)

5: cant really pencil stuff out (thats why i was asking if there is something like a smart inverter for my needs and if it’s true with the 50% battery)
 
1: have no idea, haven’t bought or scavenged a single piece of equipment yet, so I’ll i have to go is from my “wishlist of appliances”.
Good! Don't spend a dime until you've done as much homework as possible. It's really REALLY annoying to buy something and then find out it doesn't do what you need it to do. Take my bin-o'-spare-parts as an example.
Don’t know what system. Like I said I’m an open book so what system is best for me? read something that 48v systems can handle more watts at a single time. So I’m thinking 48v?
Anything over about 3000w, which it sounds like you're going to need, should be 48v. I'd plan to go that way right out the gate.
Don’t have any solar panels and don’t know what’s available over here yet (but keep in mind, almost everything that’s sold here is chinesium and is the cheapest of the cheapest crap)
Availability is going to be one of the things you have to research. Since pretty much all solar panels available are Chineseium you're going to be stuck with that anyways, so don't sweat it.
1a: the house is going to be in Sub Saharan west Africa, 9 months out of the year sun sun sun but 3 months rainy and can get really cloudy.
OK, so one of the nice things about the Power Audit form is that you can do as many versions as you like. Hit up the PVWatts and JRC sites (that hopefully someone here can link for you soon) and see what your production would look like at the best of times and at the worst of times. You might find that a generator is needed during the cloudy months, or you might find out that you can just over-panel for cheap and it won't be an issue.
2: again have no idea what I want to use, that’s why I’m over here for advice, does a system like i mentioned even exist? It’s 220v European type (at least all European appliances work over here) capacity I understand but I don’t know how much my system is going to need in the first place.
Oh yeah, you've got all sorts of options from All-In-Ones that will do your panels, batteries, and inverting all in one convenient box and can be stacked to going piecemeal and having separate components. Or a combination of both if you really want to. It's kinda like Lego's, you just have to start with the picture on the box and then stick the right pieces in the right place.
3: I have no idea what my budget is going to be. What do you recommend for a setup that I need that’s good but budget friendly?
Solar and Budget Friendly have an interesting relationship. When you do your power audits, I recommend doing at Least 3 of them. Start with the audit that has ALL the pumps and aircon and Margarita-Master-9000's and swimming pools and automatic dog washers and such. Then do one with the absolute bare necessities like lights, water, and USB charging. Then your 3rd one will be the more Realistic one that has what you think you really want to have when the grid goes down.

The power audit is going to tell you 3 primary things;
1: How big does your inverter need to be to sustain your loads?
2: How much battery capacity do you need to sustain those loads for $N number of days
3: How much solar panel will you need to top those batteries off once the sun comes back out?

Once you know how much you use, and how much you need, then comes the How Much Can You Afford.

Somewhere between Need, Use, and Afford is the perfect-ish Venn Diagram of your solar system.

4: more then enough space (haven’t started the building of the house yet so I can make the storage as big as I want)
That's going to come in handy!

5: cant really pencil stuff out (thats why i was asking if there is something like a smart inverter for my needs and if it’s true with the 50% battery)
The 50% battery is mostly about using flavors of Lead Acid, be then FLA, AGM, or Gel. Modern LFP, or LiFePO4 batteries can use 100% of their rated capacity if need be. The up-front cost is pretty hefty but having them still plugging along after your neighbors are on their 3rd or 5th set of lead acids makes up for it.

Unfortunately your question of "What Should I Build" is really open. There's no 1-Size-Fits-All-Package that works for everybody. With a little bit of brain scratching and a bit of time you can make the system that is best for YOU. Your system won't work for me, or for Will, or for 12vInstalls, but it will be the Right system for You.
 
Lead-acid batteries will die in a few months or years if over-discharged, or if not fully charged. System needs to be designed to disconnect when low, to charge properly, and needs enough power production.

Lithium (several chemistries) die if over-charged or over-discharged, but can sit in between. Some varieties are more likely to fail from a single abuse (over charge/discharge), or to catch fire.

Neither kind of battery really likes excessively hot weather.

Systems can be built to power what you have, and to serve as backup to grid. Less expensive if limited things (e.g. refrigerators) are powered during grid failure.
Prices range from < $1000 for something small in a van/camper to > $50,000 powering large house. Batteries are often the majority of the cost. A power audit will show how much you need and help you decide what to leave unpowered.

There are some companies with a presence, installers and support, everywhere. Like SMA. Some brands, you wouldn't have anyone available who understand them. Most of us design and install our own systems, diagnose failures to the box and replace or send in for warranty. Unless you learn to do that, you need support of a company that can.

My system is grid-tied, has large amount of PV panels and SMA inverters, small battery. Most of the time it acts as a UPS. During power failure, I have enough to run A/C during the day, but at night only minor loads. We have "net metering" so when grid is up, PV backfeeds through the meter, recording credit for use other times, so what I bought produces the power I use daily, not just as backup.

pfff my head is spinning already from all the information and differences. Finding a good expert over here is really difficult, the know-how and common sense just isn’t here (last Year my fridge got on fire, the landlord send 6 different electricians. 5 of them told me with a straight face the fuse only pops when the fridge is completely burned down. So you see my scepticism)

are there all-in-one systems that can do that properly so the lifespan of my batteries will last? The average temperature here is around 30-32 degrees in the daytime. But it’s going to be stored in-house and I’m putting a thick concrete slap on the roof to keep it a couple degrees cooler indoors.

if it’s possible and a little bit budgetfriendly I want to be off the grid completely. Minus maybe a washing machine or poolpump that’s seperated for example. The grid is just to unreliable over here, right now even the power is out again For at least 2 hours. Might be for an hour more, might be until tomorrowmorning.

what I did figure out already is that I’m going to be looking and buying appliances that are the most energy efficient. Don’t want to be sold a system thats going to break down in a year or has not got enough capacity for my needs.


but I’m probably in the wrong forum because like you said this is more DIY and I’m a complete noob when it comes to all the different variaties.
 
Good! Don't spend a dime until you've done as much homework as possible. It's really REALLY annoying to buy something and then find out it doesn't do what you need it to do. Take my bin-o'-spare-parts as an example.

Anything over about 3000w, which it sounds like you're going to need, should be 48v. I'd plan to go that way right out the gate.

Availability is going to be one of the things you have to research. Since pretty much all solar panels available are Chineseium you're going to be stuck with that anyways, so don't sweat it.

OK, so one of the nice things about the Power Audit form is that you can do as many versions as you like. Hit up the PVWatts and JRC sites (that hopefully someone here can link for you soon) and see what your production would look like at the best of times and at the worst of times. You might find that a generator is needed during the cloudy months, or you might find out that you can just over-panel for cheap and it won't be an issue.

Oh yeah, you've got all sorts of options from All-In-Ones that will do your panels, batteries, and inverting all in one convenient box and can be stacked to going piecemeal and having separate components. Or a combination of both if you really want to. It's kinda like Lego's, you just have to start with the picture on the box and then stick the right pieces in the right place.

Solar and Budget Friendly have an interesting relationship. When you do your power audits, I recommend doing at Least 3 of them. Start with the audit that has ALL the pumps and aircon and Margarita-Master-9000's and swimming pools and automatic dog washers and such. Then do one with the absolute bare necessities like lights, water, and USB charging. Then your 3rd one will be the more Realistic one that has what you think you really want to have when the grid goes down.

The power audit is going to tell you 3 primary things;
1: How big does your inverter need to be to sustain your loads?
2: How much battery capacity do you need to sustain those loads for $N number of days
3: How much solar panel will you need to top those batteries off once the sun comes back out?

Once you know how much you use, and how much you need, then comes the How Much Can You Afford.

Somewhere between Need, Use, and Afford is the perfect-ish Venn Diagram of your solar system.


That's going to come in handy!


The 50% battery is mostly about using flavors of Lead Acid, be then FLA, AGM, or Gel. Modern LFP, or LiFePO4 batteries can use 100% of their rated capacity if need be. The up-front cost is pretty hefty but having them still plugging along after your neighbors are on their 3rd or 5th set of lead acids makes up for it.

Unfortunately your question of "What Should I Build" is really open. There's no 1-Size-Fits-All-Package that works for everybody. With a little bit of brain scratching and a bit of time you can make the system that is best for YOU. Your system won't work for me, or for Will, or for 12vInstalls, but it will be the Right system for You.

I meant appliances that I’m going to use in my house (so not The solar system itself)

the 48v system, is it possible to turn a section down to 12v so I can use that circuit for 12v lights and 12v fans (or is it more efficient to just use the 230v system?)

yeah I know the panels allmost all are made in china, but I mean the ones available here are probably the “aliexpress quality” ones and not the kind that are available in Europe or america.

ill try and do the forms but it’s going to be a huge ballpark area because I have no idea what my future appliances are going to need.

I was kinda hoping to avoid a generator all together, don’t know how people can sleep with that noise (not to mention the fuelprices keep getting higher and higher)

was just checking the local Facebook marketplace and saw lifep04 battery’s for sale.

lion safari ut 1300
105ah 1344wh
3500 life cycles (so that’s around 10 years right?)

508,- euro / 554,- dollar per battery

that seems quitte expensive to me or are they that great of a battery!
 
Once you built a big system, almost everything can be 230VAC.
Having some loads 12V is typically for small RV systems. But, you could have 48V to 12V DC-DC converter. Or, additional 12VDC system to power alarm, communication, etc. that accept 12V input.

"I want to be off the grid completely" will cost much more than "I'm willing to draw power from the grid when it is up."

Find out if you can have net-metering (get a credit for spinning meter backwards); if so, do that.

If not, consider "zero export" which has a current transformer to measure power from meter to your main panel.
Inverters and PV power a critical loads panel with things you want always on. They backfeed to main panel and support all household loads. If any current is detected being exported to grid, inverter output is reduced to prevent that.

You can have an inverter with transfer relay big enough to power entire house. More economical to power only critical loads.
I have inverter able to power small house, and garage normally goes dark when grid fails. But I can flip switches so inverter also feeds garage; in that case I don't run arc welder or air compressor.

Yes, 3500 cycles is about 10 years of nightly cycling. That is one of the benefits of lithium. We favor LiFePO4 over other lithium chemistries because much less likely to start a fire.

Lithium batteries are relatively new, and construction quality varies. Many have failures, and can't supply large current for motor loads due to limitation of their BMS.
Lead-acid is still good for some applications, especially freezing weather. Cycle life is about 1/5 as much as lithium, so only lasts a few years of deep cycles. Large batteries cycled 15% can last 20 years.
Probably LiFePO4 is a good choice for your application.
But if battery is only for occasional grid failure, like mine, and if kept inside an air-conditioned location, AGM like I use or Gel could be good. It is dumb, simple, maintenance free, just needs a really good charger for long life.

Lots of inverters, and BMS, have software issues and updates. That means support which probably isn't available. Your local industry probably has forklift batteries, so whatever kind those are you can get support for. FLA for sure. AGM maybe. Probably no lithium yet.

What can you spend? $3000? $10,000? More? If cost is a hard and fast limit, that dictates what you can buy.


For the SMA I like,
Sunny Island 6kW $5000, one to four units
Sunny Boy 6kW $2000, one to eight units
Battery 48V, $1200 for 100 Ah to $120,000 for 10,000 Ah

Batteries can be lead-acid or lithium. Similar price for either (except smallest lithium not quite as low cost.)
Prices of batteries vary quite a bit by brand.
For lithium, best to get a 48V battery rather than four 12V, because it manages cell voltage across all. Also preferred that BMS talks to inverter, but not mandatory.

Other brand inverters can be 1/4 the price of these. There are a number of low-cost ones, and several quality name brands similar in price to SMA.
 
Thanks for your information, at least I know now already that I’m with both feet on the ground again because it’s going to be way more then I want to spend.

ive changed my strategy and now going to go with a combination of 3, powergrid, small solar system and a generator. Powering my lights and fans and dedicaties usb outlets (for phones, iPad, soundbox ect.) and the rest on a separated system powered by the local grid and if I ever need real power when it’s down to start op the generator (AC for example in the rainy season)

but I do want to keep the option of expanding in the future and making the house off grid bit by bit. so if I’m right the lifepo4 batteries have no problems with sucking them dry? What consumes the most power? Going from a 48v battery to 12v and then directly to the 12v led lighting (is that going to cause problems with flikkering or something?) and 12v usb and 12v fans. Or just go from 48v to 230v and powering it then and using the adaptors supplied with the lighting and usb bricks. Or am I overthinking it and it doesnt consume that much more energy?

is it possible in the future if I’m going with the 12v route to later add an 230v converter next to it?


there are so many options I understand now what youre saying that you kinda need to have an expert involved
 
Anything small like AC adapters doesn't matter regarding efficiency unless you have a very small battery.
Power for air conditioning, refrigeration, etc. is what you would design a big system for. 48V battery to inverter.

For backup of small devices during a power failure I would use 12V AGM battery, float charger, possibly PV and SCC.
 
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