diy solar

diy solar

Beginner build - small 24V solar system

Pi Curio

Sunlicious
Joined
Aug 10, 2022
Messages
479
Location
Croatia
Hi all,
I've just started getting into solar systems, watching multiple youtube videos, and reading forums to get a sense of how solar works and the math behind it.

In summary, I'm trying to build a small 24V system taking the space limitations, and the orientation to the sun during winter(worst case scenario/limited 3 hours of direct sun) into consideration.

With that said, I'm thinking to get one big solar panel to get the most for the buck and available space.

Here's the thing, I'm not sure I fully understand what can and cannot work together for a specific voltage system.

More specifically, I'm looking into getting a single 550W solar panel that ranges from a 43-49V Open Circuit Voltage and use it with Victron 100V 30A charge controller and 2x 12V 100Ah LifePO4 batteries.

Can such a single 'large' panel with that Open circuit voltage work for a 24V system, will it have enough voltage in lower light? Should I go with Bifacial to help with cloudy days? Any recommendations?

Also, can you recommend a good 2000w inverter? Appreciated.

Thanks.
 
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The combination you mentioned would work but you don’t mention what the max power voltage is. Also do you have a goal for what you want to power with this setup.
 
As a side note, will you be picking up that solar panel yourself? You wouldn't want to have a single 550W panel shipped to you.

What do you plan/want to power with your test setup?
 
The 550 watt panel with OC volts at 48 and max power volts at 40 volts with max current at 14 amps should be OK with a 100/30.
A 100/20 is rated by Victron for 580 watts at 24 volts, the 100/30 related at 880 watts at 24 volts
If future expansion is planed a 150/45 would take panels in series. ( rated for 1300 watts at 24 volts. Also will work on a 48 volt system)
Low light reduces current to not very much so no real advantage in planing for low light conditions.

Bifacial needs space to the rear of the panel so would need suitable mount. Note a 550 watt panel is heavy , 28 kg, 60 lb, and bifacial is heavier, 33kg. Consider shipping cost of large panels, and possible damage in transit.

Inverter, Victron Pheonix, inverter charger, Victron miltiplus.

Mike
 
The combination you mentioned would work but you don’t mention what the max power voltage is. Also do you have a goal for what you want to power with this setup.

What does the MaxPowerVoltage means exactly? Merely trying to understand these things, really interested to learn and understand solar as much as possible considering I'm not an electrical engineer :)

The ultimate goal would be to reduce my electric bills.
Guess, I would start with a small system like this one while I wrap my head around this whole thing while also keeping an eye on the future expansion such as another panel and/or battery capacity. Why I'm also trying to invest in an adequate charge controller from the get-go, hopefully, an inverter as well depending on the total initial cost of the system.

For now, I would use it to power my laptop, lights, and tv for several hours daily or sometimes maybe a kettle or a small microwave oven for a minute or a few. Occasionally, maybe charge my power tools batteries, etc.



Btw, I've found a good offer on a 455W panel so I'll probably go with that one instead of a 550W one. Would this panel work? 455w solar panel.png
 
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As a side note, will you be picking up that solar panel yourself? You wouldn't want to have a single 550W panel shipped to you.

What do you plan/want to power with your test setup?
That's a very good point, something I was thinking about as well. Why I've decided to buy my panel from close-by stores.

As for my plan.
For now, I would use it to power my laptop, lights, and tv for a few hours daily or sometimes maybe a kettle or a small microwave oven for a minute or a few. Occasionally, maybe charge my power tools batteries, etc.

I'm hoping the 2x12V 100Ah, 2400Wh storage would do for most of it. For winter specifically. In summer there's an abundance of sun hours where I live.
Also, not certain if there is a healthy minimum battery capacity required for the 2000w inverter, I heard some mention of this somewhere but I might misunderstand what was meant by this :)
 
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What does the MaxPowerVoltage means exactly? Merely trying to understand these things, really interested to learn and understand solar as much as possible considering I'm not an electrical engineer :)

The ultimate goal would be to reduce my electric bills.
Guess, I would start with a small system like this one while I wrap my head around this whole thing while also keeping an eye on the future expansion such as another panel and/or battery capacity. Why I'm also trying to invest in an adequate charge controller from the get-go, hopefully, an inverter as well depending on the total initial cost of the system.

For now, I would use it to power my laptop, lights, and tv for a few hours daily or sometimes maybe a kettle or a small microwave for a minute or a few. Occasionally, maybe charge my power tools batteries, etc.



Btw, I've found a good offer on a 455W panel so I'll probably go with that one instead of a 550W one. Would this panel work? View attachment 106436
My understanding is that the max power voltage (MPV) is the voltage recorded in testing conditions where the panel produced its maximum wattage. I could have figured out what it was from the information you provided by dividing the watts by the amps but it didn’t cross my mind till later.
 
The 550 watt panel with OC volts at 48 and max power volts at 40 volts with max current at 14 amps should be OK with a 100/30.
A 100/20 is rated by Victron for 580 watts at 24 volts, the 100/30 related at 880 watts at 24 volts
If future expansion is planed a 150/45 would take panels in series. ( rated for 1300 watts at 24 volts. Also will work on a 48 volt system)
Low light reduces current to not very much so no real advantage in planing for low light conditions.

Bifacial needs space to the rear of the panel so would need suitable mount. Note a 550 watt panel is heavy , 28 kg, 60 lb, and bifacial is heavier, 33kg. Consider shipping cost of large panels, and possible damage in transit.

Inverter, Victron Pheonix, inverter charger, Victron miltiplus.

Mike
I'd most definitely like to expand the system one day, at least double the panel and obviously the storage capacity.

The 150/45 is nearly double the price of 100/30. With that said, would it be better to get the 100/30 now to lower the initial cost of the system and later just buy another 100/30 and sorta use both of them as a dedicated charge controller per each panel for the same battery?

Thinking,
I would also avoid serial connection panel interdependence in the case of clouds or shade on one of the panels. The most repeating thing I've heard is panels and batteries like serial connections, have downsides too. That is, if I have a correct understanding of these things, YT and forum reads are my only resources for a week or so :)

If I get a Bifacial panel I will definitely make some white fabric background with adequate distance in between. Since I have to make the mounting system that is foldable for the whole thing I should be able to tailor the fabric reflector as part of the mount.

Edit:
On second thought, I don't think I fully understood what you were saying. Victron 150/45 supports 12/24/36/48v which is real flexibility for my system expansion one day, specifically the storage capacity.

If I go with the 2x12V 100Ah now, I should be able to just get two more 12v 100Ah for a total of a decent 4800Wh later. Most definitely something I should consider now that I come to think of it.
 
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My understanding is that the max power voltage (MPV) is the voltage recorded in testing conditions where the panel produced its maximum wattage. I could have figured out what it was from the information you provided by dividing the watts by the amps but it didn’t cross my mind till later.
Thanks for helping me to understand these things, very much appreciated! Really cool way to determine the MPV, learn something new every day :)
 
Instead of creating a new thread I thought I would ask my question here.

Can you take a single 12 volt battery and then make it 24 volt with a step up transformer to start? Meaning I want to slowly build a 24 volt system. Or would it be better to just buy 2 lower capacity 12 volt batteries and wire them in series. I guess the 3rd option would be to buy a 24 volt battery from a place like Power Queen and then I could add additional batteries as required. Thanks for any insight.
 
Instead of creating a new thread I thought I would ask my question here.

Can you take a single 12 volt battery and then make it 24 volt with a step up transformer to start? Meaning I want to slowly build a 24 volt system. Or would it be better to just buy 2 lower capacity 12 volt batteries and wire them in series. I guess the 3rd option would be to buy a 24 volt battery from a place like Power Queen and then I could add additional batteries as required. Thanks for any insight.
It’s really hard to beat just having the correct battery to start with if you have the choice.
 
Instead of creating a new thread I thought I would ask my question here.

Can you take a single 12 volt battery and then make it 24 volt with a step up transformer to start? Meaning I want to slowly build a 24 volt system. Or would it be better to just buy 2 lower capacity 12 volt batteries and wire them in series. I guess the 3rd option would be to buy a 24 volt battery from a place like Power Queen and then I could add additional batteries as required. Thanks for any insig
Probably the toughest decision to make in building a solar system. LiFePo4 cost just makes it that much harder and if that's not enough, adding batteries afterwards isn't ideal either.

Having similar dilemma as well, just that in my case I'd like to leave room for future 48v transition.

Long story short, if 24V is your goal, I'd go with 24v units, just bare in mind what storage capacity you might want to have one day as there are limitations involved.

If possible starting with 200Ah 12v packs might be better, yet, it all comes down to the LiFePo4 battery cost again doesn't it. What I've said is without knowing your power needs and future plans for storage expansion, but I share similar struggle in my first build planning.

Bottom line, batteries specifically unlike most solar system components seem as either 12v or 24v (single/several) from the get go.
 
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Probably the toughest decision to make in building a solar system. LiFePo4 cost just makes it that much harder and if that's not enough, adding batteries afterwards isn't ideal either.

Having similar dilemma as well, just that in my case I'd like to leave room for future 48v transition.

Long story short, if 24V is your goal, I'd go with 24v units, just bare in mind what storage capacity you might want to have one day as there are limitations involved.

If possible starting with 200Ah 12v packs might be better, yet, it all comes down to the LiFePo4 battery cost again doesn't it. What I've said is without knowing your power needs and future plans for storage expansion, but I share similar struggle in my first build planning.

Bottom line, batteries specifically unlike most solar system components seem as either 12v or 24v (single/several) from the get go.
Mine is a "weekend" cabin/shed build. Power requirements are pretty minimal other than a small window AC unit in the summer. This is why I was going to go 24 volt. Lights will all be 12 volt with only a 1-2 things that might need an inverter. I also have a Bluetti that can cover those items. The pro to a smaller system would be if I want to run a camera or two, internet, and some other low draw items they could be on something that is installed in the shed. If we ever build a house then I would go 48v for sure. I am thinking 2500-5000 watt hours of battery capacity and somewhere between 400-1000 in solar would more than suffice.

Thanks for the reply.
 
Mine is a "weekend" cabin/shed build. Power requirements are pretty minimal other than a small window AC unit in the summer. This is why I was going to go 24 volt. Lights will all be 12 volt with only a 1-2 things that might need an inverter. I also have a Bluetti that can cover those items. The pro to a smaller system would be if I want to run a camera or two, internet, and some other low draw items they could be on something that is installed in the shed. If we ever build a house then I would go 48v for sure. I am thinking 2500-5000 watt hours of battery capacity and somewhere between 400-1000 in solar would more than suffice.

Thanks for the reply.

If you are certain about your power needs calculation and believe it will suffice, if possible, starting with 2x 12V 200Ah might be a good start.

Mind you, this is only a suggestion, it's really up to you, your budget, and your power needs/plans.

Anyhow, hope it helps a bit.
 
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As long you've taken into consideration the amount of sun you can get throughout the year, you should be golden.
Note: To charge 4000Wh with 400W of solar, it will take 10 Hours of direct Sun.
That doesn't say you'll always drain that much from the battery but is something to consider when looking at how much solar would suffice.

Something to keep in mind, I'm fairly new to solar, merely trying to help out with bits that I've learned thus far.

Anyhow, hope it helps a bit.

Appreciate all of the info. Location is desert SW with plenty of sun and no shading from trees or other obstructions. I will keep researching and planning though! Thanks again.
 
Appreciate all of the info. Location is desert SW with plenty of sun and no shading from trees or other obstructions. I will keep researching and planning though! Thanks again.
Anytime :)

Sounds like you have the perfect conditions for a solar system, solar panels were made to sit outside in the sun :)

Imho, storage(batteries) is not the real ROI part in a solar system. It's the capacity for electricity generation during the day that makes the difference, with the battery reserves during the night or for less than ideal rainy days.

I'd suggest going as far with solar power as you can get away with from the get-go. If your PV(solar) production is greater, you'll be able to use it to power the load during the day without much reaching into the battery storage.

Also, might be worth buying a book, personally, I've ordered solar for dummies and another one with more topic depth. The former one will probably be a good reference point by the time I receive it, still, I'm sure there'll be bits I haven't heard of on forums or videos worth knowing.

When you think about it, we are about to invest thousands of $ into the build, spending a couple of tens more from the get-go is an investment well worth making IMO.

Just thought it would be worth mentioning. :)


Anyhow, hope it helps.
 
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