1st solar power system

What do you think of this system? Which inverter? And how many solar panels?

We like MPPT charge controllers for wide temperature range and connecting a (high voltage) series string of panels.
Your $25 charge controller is PWM because ... it is $25. PWM can be OK, but know what range of panel voltages it works with.

one inverter is 12V, the other is 48V. Obviously 12V is convenient off your car battery. 48V draws 1/4 the current so thinner wires, better for higher power. One says "sine wave", the other doesn't. Some things (e.g. motors, some electronics) prefer sine wave.

Always start with what you're trying to do.
Mobile? Man-portable? Fixed at home?
What are the loads you are trying to operate? If motors, they may draw 5x the current on nameplate, if only for a fraction of a second. Inverter must produce that.
How many total watt-hours do you plan to use per day? Is that while sun shines, or entirely at night?
Batteries ... some are called "deep cycle", some actually are deep cycle. Some are safe, even to carry on airplanes. Some should only be kept in a fireproof building. Some last one year, some last 20 years.

How much do you want to spend? $$$ $$$

Hedges said:

We like MPPT charge controllers for wide temperature range and connecting a (high voltage) series string of panels.
Your $25 charge controller is PWM because ... it is $25. PWM can be OK, but know what range of panel voltages it works with.

one inverter is 12V, the other is 48V. Obviously 12V is convenient off your car battery. 48V draws 1/4 the current so thinner wires, better for higher power. One says "sine wave", the other doesn't. Some things (e.g. motors, some electronics) prefer sine wave.

Always start with what you're trying to do.
Mobile? Man-portable? Fixed at home?
What are the loads you are trying to operate? If motors, they may draw 5x the current on nameplate, if only for a fraction of a second. Inverter must produce that.
How many total watt-hours do you plan to use per day? Is that while sun shines, or entirely at night?
Batteries ... some are called "deep cycle", some actually are deep cycle. Some are safe, even to carry on airplanes. Some should only be kept in a fireproof building. Some last one year, some last 20 years.

How much do you want to spend? $$$ $$$

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Ultimately my whole house. I just want to start small get some knowledge. I would like to keep it under $2k to start.

For an RV build, I would expect you to spend four to ten times the cost of solar panels, and that would be the real cost of wires, mounting equipment, brackets, wiring, circuit breakers fuses, a set of MC4 crimpers. I’ve seen kits selling for much less, but they always leave something out, like the batteries, wiring, brackets, etc,,

With a PWM controller like you listed, a 400 watt inverter, a 100 watt solar panel, A 92 AH Deep cycle battery, some wiring from Home Depot, and some Anderson Connectors, I put together a ”solar Generator,” but that will not power a whole lot except charge iPads and a few USB devices. It can power more, but the 92 AH lead acid battery is limiting to the power it can provide.

This site has some good example systems to bawe a build off of, and Will Prowess the site owner, has a book if you have kindle unlimited, you can download for free.

Godfather777 said:

Ultimately my whole house. I just want to start small get some knowledge. I would like to keep it under $2k to start.

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The charge controller and inverters you listed are low end junk.
The battery is dubious too.

There are several things that need to fall within range to work.
Solar panels have an "open circuit voltage" and that gets higher when cold. It must not be allowed to go higher than charge controller spec.
They have a maximum power voltage, and that gets lower when it. If less than charge controller range, won't put out much power. Range depends on battery voltage.

Batteries have a maximum recommended charge rate. Too many watts of panels, and battery is charged too quickly, shortening life.
They have a number of usable cycles vs. depth of discharge. Batteries vary greatly in this regard, depending on chemistry and model.

Certainly for $2k you can build something nice, that will operate some equipment during power failures.
The things you listed above might build something for $500 but would be less capable.

There are some deals out there on used equipment, but you need to make sure your selection fits together well.

Since you're starting small to learn, you could select a 12V inverter you might later use as portable for your car or truck, and get a used automotive battery for practice. But if you get a good MPPT charge controller that supports 12/24/48V that could work for practice and work for your future system. The panels would support both as well.

You could also build something with no inverter, providing 12V battery backup with solar power for your internet equipment and computers, assuming they all have 12V jacks.

Future system: Do you want grid-tie, no batteries, offsets your electric bill by spinning the meter backwards?
Or do you want battery backup to run computer, refrigerator, air conditioner during power failures?
Or both?
There are several brands and configurations for any of those.

Hedges said:

There are several things that need to fall within range to work.
Solar panels have an "open circuit voltage" and that gets higher when cold. It must not be allowed to go higher than charge controller spec.
They have a maximum power voltage, and that gets lower when it. If less than charge controller range, won't put out much power. Range depends on battery voltage.

Batteries have a maximum recommended charge rate. Too many watts of panels, and battery is charged too quickly, shortening life.
They have a number of usable cycles vs. depth of discharge. Batteries vary greatly in this regard, depending on chemistry and model.

Certainly for $2k you can build something nice, that will operate some equipment during power failures.
The things you listed above might build something for $500 but would be less capable.

There are some deals out there on used equipment, but you need to make sure your selection fits together well.

Since you're starting small to learn, you could select a 12V inverter you might later use as portable for your car or truck, and get a used automotive battery for practice. But if you get a good MPPT charge controller that supports 12/24/48V that could work for practice and work for your future system. The panels would support both as well.

You could also build something with no inverter, providing 12V battery backup with solar power for your internet equipment and computers, assuming they all have 12V jacks.

Future system: Do you want grid-tie, no batteries, offsets your electric bill by spinning the meter backwards?
Or do you want battery backup to run computer, refrigerator, air conditioner during power failures?

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I would like something that would run some part of my saltwater pond for now. I have a saltwater pond and my electric bill is too high. Also would keep the vital systems running no matter if the power goes out or not. ie a pump and heater and maybe some lights.

Godfather777 said:

I would like something that would run some part of my saltwater pond for now. I have a saltwater pond and my electric bill is too high. Also would keep the vital systems running no matter if the power goes out or not. ie a pump and heater and maybe some lights.

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Also I get the panels for free so they are not part of the cost.

So start with the thing you need to power. Pumps and heater - all 120V? How many watts?
You can start with the label, and actual power will be less than that except motor start-up.
Some people recommend Kill-a-Watt to measure actual consumption.
Heater switches on and off. If you know the percentage on time you can better estimate watt-hours per day.

From that size battery - at least 12 hours run time for night, ideally 72 hours for 3 winter days with no sun.
Size inverter. calculate how man panels, considering short winter days and efficiency loss of inverter and charge controller.
Size charge controller.
Tentatively select equipment, based on performance, quality features.
Beyond that, it is hardware and wires.

Do you want to mess with grid-tie, now or in the future? There are setups that have batteries and export surplus to the grid. While your system is small, it will never make more than your house consumes. With more panels it could. If set up so batteries remain charged 24/7 except during grid failure, then less expensive batteries can last 10 years. If batteries cycle every night they will cost more.

I'd recommend you keep it off the grid for now.
Just contain your salt water system on the solar off grid setup. I think conceptually this is the easiest and since you already have the panels and are ready to go with a cheap PWM charge controller why not?
Do like @Hedges recommends and make sure to measure the actual power consumption of your complete saltwater pond system (by the way, neat! I didn't know people made saltwater ponds. ) Just run everything through a watt meter for 24 hours, or better if you can do a few days then divide the consumption by days to know.
Take that number, divide by 4 to see about how much your panels need to put out (fudge factor included). As long as they add up you should be good. You can get fancy later and add an ATS switch to fall over to mains if you run out of juice in your batteries.
Make sure your inverter is pure sine wave as pumps don't always play nicely with the cheapo modified sine inverters.

Actually, you may need to consult with solar providers, as the requirements might be very different for each site, its location as well as your needs. When I was about to install solar panels, I used to ask a lot of question like you to almost everyone with solar experience but it turned out that my case was a bit different and none of the suggestions was feasible for me. Then, I contacted directly to the company I wanted to go solar with and they helped me a lot to make an informed decision. If you are interested, they operate in Nevada, Texas, and California. To reach them you might visit LA Solar Group on FB and PM them your number with consultation request.

Carol_D said:

Actually, you may need to consult with solar providers, as the requirements might be very different for each site, its location as well as your needs. When I was about to install solar panels, I used to ask a lot of question like you to almost everyone with solar experience but it turned out that my case was a bit different and none of the suggestions was feasible for me. Then, I contacted directly to the company I wanted to go solar with and they helped me a lot to make an informed decision. If you are interested, they operate in Nevada, Texas, and California. To reach them you might visit LA Solar Group on FB and PM them your number with consultation request.

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I do understand what you are saying, but you are assuming the people on this forum are not experts.

Jeremiah said:

I'd recommend you keep it off the grid for now.
Just contain your salt water system on the solar off grid setup. I think conceptually this is the easiest and since you already have the panels and are ready to go with a cheap PWM charge controller why not?
Do like @Hedges recommends and make sure to measure the actual power consumption of your complete saltwater pond system (by the way, neat! I didn't know people made saltwater ponds. ) Just run everything through a watt meter for 24 hours, or better if you can do a few days then divide the consumption by days to know.
Take that number, divide by 4 to see about how much your panels need to put out (fudge factor included). As long as they add up you should be good. You can get fancy later and add an ATS switch to fall over to mains if you run out of juice in your batteries.
Make sure your inverter is pure sine wave as pumps don't always play nicely with the cheapo modified sine inverters.

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I am looking at going with a 48v growatt mppt. How many batteries (lifepo4) and panels would you suggest I start with? I will be able to but a load on it my whole system uses 20 KWH. My plan is to go with the growatt and the lease amount of batteries and panels to start. was I get it going I can add more and even add another growatt.

Godfather777 said:

I am looking at going with a 48v growatt mppt. How many batteries (lifepo4) and panels would you suggest I start with?

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@Hedges this question is for you too.

LiFePO is supposed to have good cycle life, so I think that means OK to cycle deeply. I haven't used them; I use AGM for my grid-backup system and expect 10 years with infrequent cycling.

You need to determine how many watt hours you need to cycle each day (12 hours of night). And, if you want the batteries to keep the fish pond going for 3 days of heavy clouds (6 times as large a battery) or not. If you would be around you could start a small generator if necessary. Downside with a large battery is it will grow old before the shallow cycles have worn it out.

If I was using AGM I would size it so 12 hours was 15% to DoD. That might give me 10 years. Occasional 90% discharge would be supported.
My other option would be for 12 hours to be 70% to 90% discharge, but have grid power keep the battery charged. Then it only cycles during power failure. That is exactly what I have done for full-house backup with grid-tie inverters. (A hybrid inverter with solar priority might do that for you on a small scale.)

How large or small your load is will determine battery size and cost of the options.

Hedges said:

LiFePO is supposed to have good cycle life, so I think that means OK to cycle deeply. I haven't used them; I use AGM for my grid-backup system and expect 10 years with infrequent cycling.

You need to determine how many watt hours you need to cycle each day (12 hours of night). And, if you want the batteries to keep the fish pond going for 3 days of heavy clouds (6 times as large a battery) or not. If you would be around you could start a small generator if necessary. Downside with a large battery is it will grow old before the shallow cycles have worn it out.

If I was using AGM I would size it so 12 hours was 15% to DoD. That might give me 10 years. Occasional 90% discharge would be supported.
My other option would be for 12 hours to be 70% to 90% discharge, but have grid power keep the battery charged. Then it only cycles during power failure. That is exactly what I have done for full-house backup with grid-tie inverters. (A hybrid inverter with solar priority might do that for you on a small scale.)

How large or small your load is will determine battery size and cost of the options.

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I have the budget to spend 2k and the growatt is about 800 so I have 1200 hundred to play with that won't leave much room for to many batteries. I figured I would run the growatt with a grid connector so that the grid would take over once the batteries got low. That way I could cycle as much or as litttle has needed.

Godfather777 said:

I have the budget to spend 2k and the growatt is about 800 so I have 1200 hundred to play with that won't leave much room for to many batteries. I figured I would run the growatt with a grid connector so that the grid would take over once the batteries got low. That way I could cycle as much or as litttle has needed.

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Sounds good, but first figure out how much current your equipment draws.
AGM is cheaper than LiFePO, and wet cell is cheaper than AGM.
(But some people as Trojan golf cart batteries don't last long, so wet cell may only be a good deal in the long run for large forklift batteries)
So I think quality AGM kept at float voltage could be the economical way to have backup for 5 to 10 years.

PV is cheap (free in your case), so PV sized to produce all needed power for most hours of the day would keep battery floating. Charge controller drawing from grid at a just slightly lower voltage should keep them from discharging at night. My system does it with grid-tie PV inverters and separate battery inverter which floats the batteries while grid up, form local grid to keep grid-tie PV inverters operating during grid failure. You just need to make sure the growatt can operate batteries the way you want.

$1200 is about 400Ah of 12V SunXtender AGM batteries, about 5kWh. So 400 W draw would be 100% DoD overnight.

Hedges said:

Sounds good, but first figure out how much current your equipment draws.
AGM is cheaper than LiFePO, and wet cell is cheaper than AGM.
(But some people as Trojan golf cart batteries don't last long, so wet cell may only be a good deal in the long run for large forklift batteries)
So I think quality AGM kept at float voltage could be the economical way to have backup for 5 to 10 years.

PV is cheap (free in your case), so PV sized to produce all needed power for most hours of the day would keep battery floating. Charge controller drawing from grid at a just slightly lower voltage should keep them from dischakrging at night. My system does it with grid-tie PV inverters and separate battery inverter which floats the batteries while grid up, form local grid to keep grid-tie PV inverters operating during grid failure. You just need to make sure the growatt can operate batteries the way you want.

$1200 is about 400Ah of 12V SunXtender AGM batteries, about 5kWh. So 400 W draw would be 100% DoD overnight.

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Yea I can't find my kill a watt meter at the moment. I have a basement project going on too. So it is buried somewhere. I was thinking about one of these https://bigbattery.com/product-category/home-battery-storage/. I know that the 24v I would have to run in series to get 48v. I also know I am going to be spending a bit more. What do you think of these? so if I am understanding this correctly. I need 500 ah to get 20kwh.

The first one is 26V, 90 Ah, $900

With Lithium, you're paying a premium to have perhaps 5000 cycles to 90% DoD. It is cheaper to use grid power at night. Prices are coming down, of course. I think they are now cheaper per cycle than AGM, but not cheaper overall unless you use all the cycles.

Here's the brand of AGM I use, which I think will be lower cost but not as many deep cycles. Their tech specs show DoD vs. cycles. For backup rather than off-grid, I think they are more economical (at present)

You can probably power your fish tank with 12V, 24V, or 48V.
Start with label ratings to see what power they might draw. Then observe how long heater is on vs. off.
If you have a suitable ammeter you can take a current reading, see how much less than the label.

Hedges said:

The first one is 26V, 90 Ah, $900

With Lithium, you're paying a premium to have perhaps 5000 cycles to 90% DoD. It is cheaper to use grid power at night. Prices are coming down, of course. I think they are now cheaper per cycle than AGM, but not cheaper overall unless you use all the cycles.

Here's the brand of AGM I use, which I think will be lower cost but not as many deep cycles. Their tech specs show DoD vs. cycles. For backup rather than off-grid, I think they are more economical (at present)

Sun Xtender Solar Batteries - Photovoltaic Battery

The Sun Xtender Battery line consists of specialty lead-acid solar, photovoltaic batteries, and renewable energy storage batteries manufactured by Concorde Battery Corporation.

sunxtender.com

You can probably power your fish tank with 12V, 24V, or 48V.
Start with label ratings to see what power they might draw. Then observe how long heater is on vs. off.
If you have a suitable ammeter you can take a current reading, see how much less than the label.

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Awesome, Thanks! let me chew on this information for a bit. Also trying and find my meters.