Hi, I´m new to solar, don´t yet have a system, but have an ok idea about what I need

FrederikSchack

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Hi,

We are going solar, not for the economy of it, but for power stability and disaster preparedness.

We live in Uruguay and we have a lot of power outages and power surges where I live.

I have fairly good idea what I need, but would love to have some critical feedback.

Best regards,
Frederik
 

Boondock Saint

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Hi,

We are going solar, not for the economy of it, but for power stability and disaster preparedness.

We live in Uruguay and we have a lot of power outages and power surges where I live.
Welcome to the forum!

As for the power backup - you can tie a new system into your existing house infrastructure or you can have something that you can switch when you want, or standalone.

The caveat to switched and standalone is it will not help you with brownouts and surges.

You can buy an ALL IN ONE inverter charger and a battery bank, and use this as a UPS to regulate your A/C and kick in instantly when the power cuts out, your lights won't flicker etc.

A unit like the Victron Quattro 5000VA will do this, and even auto start and run a generator if the battery voltage were to become low. I prefer Victron because of the build quality and amount of support, so I paid more for the reliability and quality.

Based on some recent threads I would suggest you also find a highly qualified and reputable electrician / company that will tie in your system to your house.

If you want to avail of solar to charge batteries (you don't have to) you could add some panels and the proper rated Solar Charge Controller - SCC and they tie into the battery bank directly. Victron makes end to end solutions where the parts communicate and manage all of this.

Hope this helps a bit. There are lots of options to chose from.

.
 

FrederikSchack

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Thanks for the responses, I wanted to get into the deeper parts after the small introduction :)

We live in Uruguay and we´re a blessed with a lot of sun and a lot of incompetent professionals So I might end up doing it myself, even though I would prefer a professional installer.

I also had to wire the house myself, after talking with some of these "professionals".

The primary reasons for installing solar system is unreliable power from the grid. The power is usually out for 15 minutes and sometimes for a few hours, a couple of days ago we were without power for about 5 hours. There may also be fluctuations in the voltage. So the system needs to work sort of like power stabilizer and UPS.

The secondary reason is to be able to "survive", without grid-power for extended periods of time. Which means keeping the combined freezer/fridge running, heating a bit of water, having a bit of light, washing clothes. We have a big solar oven and a wood fired oven for heating/cooking, so that saves some energy.

We expect to get most of the consumed energy from the solar system, but would like the convenience of having the grid as a backup.

We don´t expect the solar system to be able to pay for itself, but probably everything besides the batteries. We pay about 0.2 USD/kWh.

We would like to keep maintenance low, keep the batteries inside the house (close to the inverter) and as mentioned it should work like an UPS.

So far I think this points in the direction of deep cycle AGM or lithium and a suitable hybrid inverter.

If we buy deep cycle AGM, then we have to consider that they are not as good at deep discharging, so we would have to buy more battery capacity to compensate for that. Further I don´t think there are any really good quality AGM here. Lithium Ion is a bit more than double the price of AGM. All in all I think they economically end up somewhere in the same ballpark. So that makes me look at other factors.

Lithium Ion has a higher roundtrip efficiency, can better utilize the stored energy at various loads and can charge/discharge faster, which should translate into better utilization of the collected energy and a better user experience. So this tips me in favor of lithium ion.

We have very limited options in regards to what we can buy here in Uruguay, haven´t seen Victron, but I can get a GroWatt 5000W hybrid inverter, that delivers 5000W and can receive maximum 8000W of solar power. I can buy Everexceed and Weco lithium batteries, with decent cycle life and warranty, but there are not many reviews about them. I can buy some good JA Solar panels with about 19% efficiency.

We have sun most days, most of the year, usually cloud free or very few clouds. According to WeatherSpark.com, the darkest day of the year has 2.5 kWh per squaremeter a day and 7.8 kWh/sqm/day at the day with the most light, but WeatherSpark.com significantly overexaggerate the amount of clouds we have. It seems that sometimes the end of winter can be cloudy and rainy.

The highest point of the sun in the summertime is about 85 degrees and about 35 degrees in the winter time. We live in the southern hemisphere, so the sun is coming from the north. I figure we would get more stable output from the panels by angling them more towards the winter sun and after doing some calculations, it seems like 45 degrees fit the bill very well.

If match our consumption with the production we could have in June, when the sun is at it´s lowest, I end up with a need of about 25 m2 of panels at 19% efficiency, which is roughly 5kW. I guesstimated and subtracted a loss of 15% in the system, if I use an efficient inverter, short cable run and lithium-ion. To be on the safe side (dirt, variation in quality of panels e.t.c.), I think 6kW is suitable?

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We would like to mount the solar panels on the roof of the porch, which is about 28 m2 and is facing north (slightly tilted, I think 5 degrees).

We would like the system to discharge max 60% and then switch to grid power, but have the ability to discharge further in case of power outages. It would be ok if the emergency discharge was able to cover a couple of hours without sun, as we rarely have longer power outages than that, I consider to have a rated battery capacity for somewhere close to a days use.

We already have 3x6mm2 cable (about 4 meter long) that goes to the porch, that could be repurposed for transporting energy from the solar panels to the inverter. As far as I can see, you can transport the power at fairly high voltages to the Growatt inverter, 120V to 550V, so this should give an insignificant voltage drop in that cable. I would like to keep them in groups of just above 120V, not to run too much power through the panels and also to some degree avoid too many panels being slowed by a panel that is not performing well.

We have laws in Uruguay, I don´t think a lot of people use them for anything, so I feel free to do whatever I want ;-D

We do very rarely get golf-ball sized hail, but would probably figure it out in advance. They caused 3 half cm deep dents on the roof of my Hilux.

Any thoughts, corrections and suggestions are very much appreciated.
 
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FrederikSchack

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I also just came across Canbus BMS today and see that the Growatt inverter and Everexceed supports it. Anybody who have experiences with it? I´ve seen one guy on YouTube having issues with it. Is it just one more thing to get gray hair from and is it worth the gray hair? :D
 

DerpsyDoodler

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I also just came across Canbus BMS today and see that the Growatt inverter and Everexceed supports it. Anybody who have experiences with it? I´ve seen one guy on YouTube having issues with it. Is it just one more thing to get gray hair from and is it worth the gray hair? :D
Have you done a power assessment? Did you find the spreadsheet on the site (click the energy audit link in my signature)?
 

Boondock Saint

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I almost fell off my barstool. My choice was War And Peace, Moby Dick, the entire Bible or your post :)

But seriously, that's pretty indepth and will probably take multiple thread to delve into and sort all the variables.

At least you already really know your infrastructure.


.
 

400bird

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I'll agree, that's quite the post.
Let's try smaller pieces of the pie.
The best first step is to do an energy audit. If you don't do that, you'll just be guessing on the system. That's what I did and many do. But, you'll likely to be either sacred off by the high cost of an oversized system or disappointed with a lower cost system that doesn't cover your needs.

For the parts I did read:
You've got some good ideas on the battery. Discharge partially, down to xx% soc, then save the rest in case of a power outage.

Any sort of lead acid battery doesn't last as long with daily cycles and even shorter if you discharge it deeply. Many types need to be vented due to the off gassing.

For the lithium, read into the section about fires. For the most part, very stable. But, not stable enough to recommend having inside the house. I'd recommend having the battery separately enclosed separated from the house. My local regulations require 5' (a little less than 2 meters)
 

FrederikSchack

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Have you done a power assessment? Did you find the spreadsheet on the site (click the energy audit link in my signature)?
Thanks for the input.

I took a high-level approach to that question. I´m usually getting close enough with ballpark measures, economy isn´t a central focus point :)

So how I see it is that I have an energy usage of about 400 kWh a month in the winter time, I dimension the panels so they can deliver this energy with the factors that I can think of taken into consideration, with the grid as a backup for the times with exceptional use. The batteries gives a buffer of roughly a days usage that distributes that energy over the day/night. The Growatt inverter I´m looking at can deliver 5000W at 230V, although it can only discharge 3000W at 230V from the battery, after that it switches over to grid. If we don´t run more than one heavy load at the time, we should be fine.

I could probably use a smaller battery capacity if it was only for buffering electricity, but I´m also considering to have a reasonably good power supply in an emergency. We don´t expect to live a fully normal life in an emergency, but will appreciate a bit of power and adapt to the sunlight that is.

Maybe I´m overlooking something here, but that was my approach.
 
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MisterSandals

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For the lithium, read into the section about fires. For the most part, very stable. But, not stable enough to recommend having inside the house.
I won't argue about safety but if i were to get lithium batteries out of my house, the first few armloads would be computers and phones. Then watch batteries, camera batteries and pacemakers.
If i were still paranoid about lithium batteries, i'd consider taking my LiFePO4 batteries out of the house.
 

Hedges

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We would like the system to discharge max 60% and then switch to grid power, but have the ability to discharge further in case of power outages. It would be ok if the emergency discharge was able to cover a couple of hours without sun, as we rarely have longer power outages than that, I consider to have a rated battery capacity for somewhere close to a days use.

Whether you should discharge batteries or not when grid is available depends on whether it will save you money.
Most batteries cost more per kWh of lifetime cycling than your grid power.

Batteries like AGM cycled daily will wear out before their float life expires, so you would be paying $0.50/kWh to use them up and have to replace them. I would only cycle them during grid outages (that's what I have and what I do with them.)

Various lithium batteries have claimed 2500 to 5000 cycle life, so cycling daily to use your own power rather than grid may make sense. A life test of batteries had only 5% of them actually reach claimed cycle life without failure, so maybe not. The commercial ones cost more than your utility rates. Only DIY LiFePO4 (or recycled cells) appear to be a way to save money.

I would keep any lithium battery bank where it could burn itself out harmlessly.

PV panels are cheaper than batteries or utility rates. It could be OK to install 4x what you need (on average) to supply peak draw with less cycling of a smaller battery, and less draw from the grid (I assume you don't have net metering.)
 

MisterSandals

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I would keep any lithium battery bank where it could burn itself out harmlessly.
I would like to do the same. Do you have any lithium batteries in your house? Laptops, phones, cameras, watches,
pacemakers, meat thermometer, heart rate monitors, bike computers, 18650 flashlights, power tools, electric toothbrush, electric razor, range finder, laser printer, a couple remotes, ... i'm counting easily over 40 just for these innocuous things in my house!

I'm guessing you have a LOT of lithium batteries in your house.
 

DerpsyDoodler

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Thanks for the input.

I took a high-level approach to that question. I´m usually getting close enough with ballpark measures, economy isn´t a central focus point :)

So how I see it is that I have an energy usage of about 400 kWh a month in the winter time, I dimension the panels so they can deliver this energy with the factors that I can think of taken into consideration, with the grid as a backup for the times with exceptional use. The batteries gives a buffer of roughly a days usage that distributes that energy over the day/night. The Growatt inverter I´m looking at can deliver 5000W at 230V, although it can only discharge 3000W at 230V from the battery, after that it switches over to grid. If we don´t run more than one heavy load at the time, we should be fine.

I could probably use a smaller battery capacity if it was only for buffering electricity, but I´m also considering to have a reasonably good power supply in an emergency. We don´t expect to live a fully normal life in an emergency, but will appreciate a bit of power and adapt to the sunlight that is.

Maybe I´m overlooking something here, but that was my approach.
You seem to have done your research. There is quite a bit of minutia to be aware of. Maybe a good next step is to draw up your circuit diagram and post it.
 

FrederikSchack

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I won't argue about safety but if i were to get lithium batteries out of my house, the first few armloads would be computers and phones. Then watch batteries, camera batteries and pacemakers.
If i were still paranoid about lithium batteries, i'd consider taking my LiFePO4 batteries out of the house.
Yes, I also feel fairly safe about lithium.

If I set up a BMS on Canbus, wouldn't I almost eliminate the problem? Doesn't that usually include a temperature probe inside the battery? The Growatt is charging up to c 0.5, I don't exactly know what that's means yet, except that is related to the overheating.

I could also put in an audible temperature alarm for extra safety of we're in the house.
 

FrederikSchack

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You seem to have done your research. There is quite a bit of minutia to be aware of. Maybe a good next step is to draw up your circuit diagram and post it.
Certainly, I'm going to make a diagram when I come home 🙂

I would much prefer to have somebody to set up the system, especially in regards to warranty and I'm now speaking with a company that I was recommended, some of the best in Uruguay. They suggested a 6kW of panels and 4kW of inverter, considering the strong sun here (short path through the atmosphere at 85 degrees) and rarely a cloud in the summertime, I think that's going to overload the inverter a lot.

So definitely I would need to be in every step of the design and implementation.
 

FrederikSchack

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Whether you should discharge batteries or not when grid is available depends on whether it will save you money.
Most batteries cost more per kWh of lifetime cycling than your grid power.

Batteries like AGM cycled daily will wear out before their float life expires, so you would be paying $0.50/kWh to use them up and have to replace them. I would only cycle them during grid outages (that's what I have and what I do with them.)

Various lithium batteries have claimed 2500 to 5000 cycle life, so cycling daily to use your own power rather than grid may make sense. A life test of batteries had only 5% of them actually reach claimed cycle life without failure, so maybe not. The commercial ones cost more than your utility rates. Only DIY LiFePO4 (or recycled cells) appear to be a way to save money.

I would keep any lithium battery bank where it could burn itself out harmlessly.

PV panels are cheaper than batteries or utility rates. It could be OK to install 4x what you need (on average) to supply peak draw with less cycling of a smaller battery, and less draw from the grid (I assume you don't have net metering.)
The economy of it isn't critical, we work abroad over the Internet and stability is especially sensitive for my wife's work. Currently we have a small UPS that keep the the most critical stuff running for 15 minutes.

The original idea was to buy a big UPS, but then I realized that a solar system would serve many more purposes. We are afraid of a really long power outage, that could put our incomes at risk.

When I have batteries to increase my own utilization, I expect the panels and inverter to be able to pay for themselves. I don't expect the cost of 7000 usd for batteries to be recovered, but that's ok.

I also consider the possibility to add another similar bank of batteries in parallel in the future.
 
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FrederikSchack

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We're also not fancy people who expect Disneyland to keep running during an emergency 😊 We're practical.
 

400bird

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When I have batteries to increase my own utilization, I expect the panels and inverter to be able to pay for themselves. I don't expect the cost of 7000 usd for batteries to be recovered, but that's ok.

That's about rights. The energy savings should eventually pay for the solar. The battery won't pay for itself directly. Sounds like your increased reliability for work and life should pay for the battery indirectly and non-monetarily
 

400bird

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Yes, I also feel fairly safe about lithium.

If I set up a BMS on Canbus, wouldn't I almost eliminate the problem? Doesn't that usually include a temperature probe inside the battery? The Growatt is charging up to c 0.5, I don't exactly know what that's means yet, except that is related to the overheating.

I could also put in an audible temperature alarm for extra safety of we're in the house.

The BMS can stop a cell that is shorted internally. Read some if the fire stories and do what you feel is right. Many of them had a BMS connected.
 

Hedges

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I would like to do the same. Do you have any lithium batteries in your house? Laptops, phones, cameras, watches,
pacemakers, meat thermometer, heart rate monitors, bike computers, 18650 flashlights, power tools, electric toothbrush, electric razor, range finder, laser printer, a couple remotes, ... i'm counting easily over 40 just for these innocuous things in my house!

I'm guessing you have a LOT of lithium batteries in your house.

We do have a couple iPhones and Dell laptops.

I have a cordless drill with AGM batteries, and several yard tools with lithium batteries but those are stored in a shed.
I'm familiar with laptop battery fires. Those were all the rage back around 2008 when Tesla selected them for cars, but those guys did find a way to manage failures. Colleagues have had puffed laptops in recent years, but not fires.

I think a difference with inverter batteries is that their scale is so large you're unlikely to put out a fire and you can't scoop them up with a shovel or cookie sheet and toss them outside.

Following a dive boat fire in Southern California, families are now suing boat owner and Coast Guard. It sounded like fire started by charging of customer's gadgets. Maybe such things belong in a fireproof box outside with lid that drops when a link melts.

If you're afraid your pacemaker might catch fire, I suggest you sleep in the yard.

But seriously, DIY lithium batteries (including LiFePO4) and commercial lithium batteries (usually of the explody variety) for inverters have been a source of fire, probably at a much higher rate than name-brand gadgets. Off-brand gadgets have also been a problem. Name-brand gadgets were a bigger issue for a while when counterfeit batteries got in the authorized distributer food chain, also issues with major vendors. Oh, and cars (other than Tesla) are getting to be a bigger deal right now. Apparently Tesla designed their cars to deal with 1 in a million bad batteries, but Chevy did not.
 
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