Off-grid 24V solar system - What do u think about ¿?

[vvillymalcom]

Hello everyone ! I'm from Spain and thanks to DiY's YouTube channel I don't feel like a beginner (but I'm a super beginner ?).

My Energy needs are 2,27 KWh/day and I would like to build an off-grid solar system to my van-truck.

I was investigating and making some math's, and this is my proposal making a 24Volts system (Every point has a link to the sources):
> 2x 410W 24V solar panel (I don't know which one buy: ZnShine or Tensite)
> 1x RENOGY Rover Li 40A MPPT Solar Charge Controller (I bought this one because 820W/24V = 34 Amp)
> 1x Victron Phoenix Inverter 24/500 230V (At most I need 250W in 220V)
> 2x LiFePo4 100Ah 12V in serie (creating a 24V - 100Ah battery)

What about your point of view ? I'm supper nervous about this, it's my first VAN, my first Solar System and both together it's gonna be my new home/life
Thanks

Picture example:







Thanks

 

[Tomthumb62]

You said your energy needs are 2.27kWh (2,27 to you in Europe). What ARE those loads? I mean, how do you know that a 500VA (approximately 400W) inverter will be enough for your needs?

 

[vvillymalcom]

You said your energy needs are 2.27kWh (2,27 to you in Europe). What ARE those loads? I mean, how do you know that a 500VA (approximately 400W) inverter will be enough for your needs?

Firs of all, thanks for answering.

I used a TP-Link Tapo P115 to monitor:
a Freezer(24h working) that shows 1,2Kwh/day
Monitor pc + computer(4h) 0.4Kw/day
lights and something else(6h) 0.4kw/day
Total: More or Less 2,0Kw/day + lose from inverter... 2,3KW/h

This are my energy needs.

About the inversor, getting all the Watts about all my devices or electrodomèstics from 230V I got more or less around 160W-200W,
60W-70W from freezer and the rest (computer, pump, lights... is more or less another 100W.
I hope that with this inversor I'm gonna have enough.

It's everything ok?

 

[Tomthumb62]

Firs of all, thanks for answering.

I used a TP-Link Tapo P115 to monitor:
a Freezer(24h working) that shows 1,2Kwh/day
Monitor pc + computer(4h) 0.4Kw/day
lights and something else(6h) 0.4kw/day
Total: More or Less 2,0Kw/day + lose from inverter... 2,3KW/h

This are my energy needs.

About the inversor, getting all the Watts about all my devices or electrodomèstics from 230V I got more or less around 160W-200W,
60W-70W from freezer and the rest (computer, pump, lights... is more or less another 100W.
I hope that with this inversor I'm gonna have enough.

It's everything ok?

That’s a great start!

Now you have the watts used.

Now you need to know surge current. So your freezer uses 1.2kwh per day. How many watts does it use when the compressor starts up? You need a clamp meter that can read up to 600ADC for best results. Or you can estimate like I show below.

Let’s take your 1.2kwh and divide by 24 hours = 50W. That’s an average. We need the highest watts it would ever draw continuously. Let’s say 85W. Multiply that by TEN to get an estimate for surge power, 85W x 4 = 850W. The surge will happen for 0.3 to 1.5 seconds, usually. So you can see that a 350VA inverter isn’t going to cut it. It might have a surge ability of 750-800VA, but real world watts would be more like 600-700W. Even if it does run, it’s pretty tough on the inverter. But it’sa Victron so maybe it can handle it Ava if you’re lucky it won’t die an early death. Go for the 800VA model at least, it will be able to run it no problem (assuming your measurements are accurate) but if you want to run power tools, you’re going to want the 1200VA model.

For the record, we have a fridge with electrical needs very similar to yours. We use the Victron 12/1200 and it runs like a dream. We could’ve gone with a smaller model, like the 12/800, but am very glad we didn’t. There was very little advantage of going any smaller, in my opinion. Already we’re downsizing from a 2000W to the Victron 1200VA (1000W).

 

[HarryN]

The decision of 24 volts is good.

Try to avoid anything renogy if you can - especially that charge controller.

If you can find 24 volt refrigerators and freezers, the power reduction per day will be fairly dramatic. (the cost will be higher )

I build these kinds of electrical systems on vans in the US. I urge you to consider to use the smaller 200 watt size panels instead of 400 watt size. They are more expensive but they allow more ability to fasten them down so they are better when driving on windy days.

 

[vvillymalcom]

That’s a great start!

Now you have the watts used.

Now you need to know surge current. So your freezer uses 1.2kwh per day. How many watts does it use when the compressor starts up? You need a clamp meter that can read up to 600ADC for best results. Or you can estimate like I show below.

Let’s take your 1.2kwh and divide by 24 hours = 50W. That’s an average. We need the highest watts it would ever draw continuously. Let’s say 85W. Multiply that by TEN to get an estimate for surge power, 85W x 4 = 850W. The surge will happen for 0.3 to 1.5 seconds, usually. So you can see that a 350VA inverter isn’t going to cut it. It might have a surge ability of 750-800VA, but real world watts would be more like 600-700W. Even if it does run, it’s pretty tough on the inverter. But it’sa Victron so maybe it can handle it Ava if you’re lucky it won’t die an early death. Go for the 800VA model at least, it will be able to run it no problem (assuming your measurements are accurate) but if you want to run power tools, you’re going to want the 1200VA model.

For the record, we have a fridge with electrical needs very similar to yours. We use the Victron 12/1200 and it runs like a dream. We could’ve gone with a smaller model, like the 12/800, but am very glad we didn’t. There was very little advantage of going any smaller, in my opinion. Already we’re downsizing from a 2000W to the Victron 1200VA (1000W).

Wow! A lot of interesting knowledge for me.

I'm gonna use your example and math's to ask and resolve my questions about it.
> When you talk about surge power, I guess it's the same that when we are talking about peak power. Actually I didn't select the 350VA inverter, I selected the 500VA which specifications are 900W peak power.


> After read your comments I turned on my freezer (230V) and you're right, this equipment consumes more than 50W in that moment (starting from 0) even more than 1,5 seconds keeps 96W at 20pm, consuming less and less until 21 when stabilises near 55W.

Hight Value	Graph during 3h 29minutes​	Low Value
​	​	​

​

> But with this numbers, how we will arrive at 850W ?¿ Why we multiply by 10 ?¿
With my maths I could go to the 24|500 inverter, but for sure I'm missing something and I want to learn about 'where'.

Thanks

 

[vvillymalcom]

The decision of 24 volts is good.

Try to avoid anything renogy if you can - especially that charge controller.

If you can find 24 volt refrigerators and freezers, the power reduction per day will be fairly dramatic. (the cost will be higher )

I build these kinds of electrical systems on vans in the US. I urge you to consider to use the smaller 200 watt size panels instead of 400 watt size. They are more expensive but they allow more ability to fasten them down so they are better when driving on windy days.

RENOGY - OMG really? I read something about the little renogy controllers, but no about this one. The specifications were SUPER. What kind of problems are reporting the users? Do you have any thread link? And what brant do you recommend ?

24volt refrigerators and freezers... yes, it's the idea, but I didn't find any one with the specs I need. In the future I would like to change the compressor.

About solar panels, I'm gonna consider that because the installation it's in a small truck. Something like that:


I appreciate allot your time and answers, all of you.
Thanks

 

[HarryN]

RENOGY - OMG really? I read something about the little renogy controllers, but no about this one. The specifications were SUPER. What kind of problems are reporting the users? Do you have any thread link? And what brant do you recommend ?

24volt refrigerators and freezers... yes, it's the idea, but I didn't find any one with the specs I need. In the future I would like to change the compressor.

About solar panels, I'm gonna consider that because the installation it's in a small truck. Something like that:
View attachment 158161

I appreciate allot your time and answers, all of you.
Thanks

Personal experience and if you do some searching you will find plenty of reasons.

 

[HarryN]

Vehicle Mounted Systems

RV's, Vans, Trucks and More! Typically 12v, and 100-1000w, but the limits are endless!

diysolarforum.com

This is a whole section of the forum dedicated to vehicle mounted power systems with a lot of general information.

 

[ShaneC]

If you've bought the renogy charge controller already and can't easily return it then I wouldn't be too concerned, just stick with it, it's likely to work fine for your situation. If you haven't then I'd recommend looking at Epever for the best budget option or victron for high quality.

 

[DIYrich]

If you are using a victron inverter, consider a victron charge controller. May also want a victron smart shunt. Hopefully there is one app you can control all 3.

 

[vvillymalcom]

If you are using a victron inverter, consider a victron charge controller. May also want a victron smart shunt. Hopefully there is one app you can control all 3.

Yes, and then all the victron ecosystem hahaha
Sometimes I'm stuck thinking that the only option, the only good option is Victron. And I don't like this kind of feeling. BUT, it seems like no one have a bad opinion about Victron.

@ShaneC thanks for the option Epever, The price is more or less the same if we compare with Renogy.

 

[HarryN]

I have no big complaints about victron but I think it is easy to imagine that having all one color of products means that you will not have any issues and it will all just work well together.

What I often see is that the interactions can be complex and people spend a great deal of time chasing if a setting in box A affects the settings in box B or C. The graphs are pretty but in my mind, it is more complex than it needs to be for the simple task of turning sunlight into electricity. Do you want to spend your day staring at pretty screens or just doing your life as you like and largely ignoring how many electrons were produced ?

To some extent, it depends if the weather you are in will be nearly always full of sunshine or there are seasons where it will be quite overcast.

When there is a lot of sunshine, then anyone can make a lot of electricity.

When there is a lot of overcast, and the sun angles are low, this is what separates those who have sucked water through a long straw from those who have not.

For then - I use bogart engineering products.

 

[HarryN]

In the US I would look at the Alte store or solar-electric.com

Between those two on line retailers they carry a bunch of brands.

DIY Solar Power & Energy Storage System Resources | | altE

altE is the #1 online source for DIY solar power and energy storage, solar education, and system installation support. Get a quote or call 877-878-4060.

www.altestore.com

NAZ Solar Electric | Off Grid & Grid-Tied Solar Power Systems

Solar power equipment for homes, businesses boats and RVs. Backed by industry experts ready to help get your solar system up and running.

www.solar-electric.com

- Bogart Engineering Battery Monitors

Bogart Engineering is the manufacturer of Trimetric & Pentametric brand of battery monitors & solar chargers. We're a team of engineers & scientists with experience in solar & battery technologies. If you researching batteries or solar technologies for use in your RV and have questions or need...

www.bogartengineering.com

MidNite Solar Alternative Energy Products: E-Panels to Inverters

MidNite Solar offers a large variety of alternative energy products from E-panels to charge controllers and inverters.

www.midnitesolar.com

and of course also victron.

Those are just example places that carry stuff but it covers the bulk of the brands that I have used.

Some of those might sell in Europe or there might be EU distributors.

 

[vvillymalcom]

Thanks all of you.
> After some research I saw some problems with the mppt Renogy because of the BT connection, but no complaints about efficiency or another problems. And about BT, I don't want to use after the first installation.

> About Victron, it seems a strong system, after resolve the math's about the system I will search and compare the different brands like Epever.

> Now I need some help/answers for the comment from @Tomthumb62 ; I don't understand his math's and the reason's (comments #4 and #6).

I will waiting for you ^_^. All of you are my light to found the path


oh! About the freezer, this was the Power Usage (W) in 24hours. During some hours was making some start and stop using between 0 and 59W

​

 

[JWLV]

Nothing wrong with Renogy in my opinion. I have two of those Renogy Rover MPPT charge controllers. I still use one and other is a backup because I've replaced it with a Growatt.

I would suggest to get at least two more 100A batteries. Or get the EG4 24V 200A server rack battery. The reasoning for this is because you have a critical device, that is, your freezer. I assume that you wouldn't want your food to go bad. Having two 100A batteries might last you a full day if you don't use anything else. But there might be occasions when you get no sun and rain all day. If I was building this, I would want at least 4 days of power when there is no solar generation.

 

[billvon]

I was investigating and making some math's, and this is my proposal making a 24Volts system

Does your van/truck have a 24V system? If yes, good idea. If not, I would go with 12V for compatibility.

I would also consider LFP batteries just so you can get more storage for the same weight.

 

[vvillymalcom]

Does your van/truck have a 24V system? If yes, good idea. If not, I would go with 12V for compatibility.

I would also consider LFP batteries just so you can get more storage for the same weight.

My truck have 12V system, but I want to isolate it. It's a new circuit isolated, then I prefer to create 24V system for my little home.

LFP batteries and LiFePo4 batteries, is not the same ? I'm already considering this as you can see at the picture above.

Thanks

 

[vvillymalcom]

Nothing wrong with Renogy in my opinion. I have two of those Renogy Rover MPPT charge controllers. I still use one and other is a backup because I've replaced it with a Growatt.

I would suggest to get at least two more 100A batteries. Or get the EG4 24V 200A server rack battery. The reasoning for this is because you have a critical device, that is, your freezer. I assume that you wouldn't want your food to go bad. Having two 100A batteries might last you a full day if you don't use anything else. But there might be occasions when you get no sun and rain all day. If I was building this, I would want at least 4 days of power when there is no solar generation.

You're right, I'm gonna keep the food for 1 or 2 months in that freezer, I don't want to think about wasting all the food.
I didn't know about this beautiful and worth it EG4 24v server rack batteries. I need to search a little bit more because I cannot find a proper brand or shop to buy it in Europe.

About the MPPT, why did you replace with a Growatt??
Thanks

 

[vvillymalcom]

Back to the energy needs and the inverter that I need.
My total estimate Energy needs are 2,27 KWh/day and the freezer have the next values:

1.15 KWh per day	Power usage during the day	Also we know the higest Watt when start from 0 is 96W. Keeps 96W at 20pm, consuming less and less until 21 when stabilises near 55W.

I was planning to buy the inverter 24/500 from Victron which offer 900W peak power.

What do you think about?

(If you read the previous comments above #4-#6 you have the information I am referring to.)