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Help Please

Forester1234

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May 2, 2022
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Hi, I am after some advice as i am new to any sort of electrics and I am trying to get all the confusion sorted into common sense , yes I have watched hundreds of Utube videos and this is why I am confused . I have a budget of about £2500 and want a solar with 240v and 12v . My aim is to be able to use a Fridge/freezer 24/7 also need to power 2 x Cpap machines at night for our sleep apnoea they are both 60w , also charge phones,laptops,cameras and also lighting and spare storage for cloudy days . So what system would anyone advise , 12v ,24v ? A all in 1 box like a VICTRON ENERGY EASYPLUS or a Growatt or just separate components ? I cannot afford expensive batteries and just need something to give me enough power for 1 or 2 months at a time . My cabin is near Limoges in France but I live in UK . If some kind person could give me a list of products to build a suitable system that would be great . How many solar panels and what size , how to join them together also all other components including wires and sizes , what sort of wire cutter and crimper tool , also battery sizes and how many and again how to connect them together . Yes sorry it's a big ask but I am so confused . Thanks in advance .
 
I'm partial to the growatt SPF-5000-ES.
For its versatility and budget friendly price.
It's a 240v inverter, which uses a 48v battery system.
A DC to DC converter, can provide the 12v needed.
You could start with cheap led acid batteries, from a local recycling facility. And, build or buy a pre-made LiFePo4 battery in the future.
 
I only have a minute. Others will chime in shortly. A fridge for 2 months will take more than 2500. You need to do an energy audit to know what is truly required for the items you need to run. The CPAP and phones etc are not hard. the bigger items make things more complicated. you also need to figure out how much sun you get.
 
First thing to do is measure.
The questions to answer are...
q: How much energy in watt hours do I need per day?
q: What is my peak instantaneous draw in watts?
 
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.
 
First, at least 2x your budget.
My 10 year old fridge uses 2.02 kwh per 24 hours. My 9 year old upright freezer uses 1.84 kwh per 24 hours.
I would recommend that you buy a Kill-a-watt meter and actually measure and write down on a piece of paper what everything you wish to power uses in a 24 hour period.
Then you will have a baseline.
Solar array sized to produce (using the insolation multiple for your location) at least 1.5x your 24 hour consumption.
I use (on the circuits powered by my system) about 18 kwh per 24 hours. Insolation here is 5.6 hours. So, to cover consumption I need 18/5.6 =3.21 kw array. But i want some charging too. So my array is 4.2 kw expanding to 5.4.
Inverter sized to cover your peak instantaneous usage. In my case this would be my base loads plus the microwave. So base loads of about 600 watts Plus 2200 Watts Max for the microwave gives me a 3000 watt inverter. Actually a pair in split phase for 6K Watts
 
The power audit is going to be critical to this and since you have such a hard budget there are a few places you can skimp out and a few places you really can't.

Things you CAN skimp on:

Panels - Try to track down used panels pulled from a home that's upgraded or a solar farm or someone else's array that has been upgraded. The cost per watt will be pretty dramatic savings, like to the tune of $0.25/watt that I paid for my used panels VS the $0.90/watt that new panels cost on average.

Charge Controller - The Victron fanboys will tell you that it's Victron or Nothing, but there are many, MANY brands out there that will turn solar panel DC into battery DC just fine. You'll just need to be willing to give up the fancier features like Bluetooth monitoring and online data logging and dog washing and disco lights.

Batteries - While LFP batteries are a great investment overall, the up-front cost is pretty hard to swallow when you've still got to get all the other things. Look into Leisure Batteries as you can get a 100Ah-ish battery for about $100USD out the door in most places. Yes, it's only good to about 50% DoD, but to put it in reference I can buy 8x 120Ah batteries for $800 for my 24v system and get 5760Wh of usable power out of them. A pre-built LFP battery of similar capacity is over $1500USD for 4800Wh, and a DIY really isn't that much less. Yes, they may only last a few years but that buys you TIME to get LFP's in the future.

Inverter Size - If your Power Audit tells you that you need a 1344w inverter, don't spend the money on a 5000w unit. Just get what you need plus about 20%-ish.

Things you CANNOT skimp on:

Inverter Style - That cheap Modified Sine inverter is a great deal, and you can put all the money you saved towards new fridges and CPAP's when they fry out from the dirty power. Drop the bucks and get a Pure Sine inverter that is large enough to power your loads without being taxed.

Wire - Stick with real copper wire that is rated for the higher temperatures, it's going to last a lot longer under load and be much safer.

Fuses - Get the RIGHT style fuse for your system, make sure it's the right size for your needs. The tube-type "Automotive" fuses? Don't trust those. Generic knock-offs that are 1/3 the price of the name brand? Do you really want to risk it? Remember: FUSES ARE CHEAPER THAN FIRES! Having said that, you can save some cash by only getting the fuses you need and are comfortable with, usually being anything with a draw. Battery to Inverter? FUSE! Battery to step-down? FUSE! 12v fuse block, well obviously fuses. SCC to battery? Eh. Fuses on both positive and negative lines of everything? Seriously?

There's going to be a LOT of give & take, but the nice thing about the Power Audit form is that it can be done many times with different setups. Start with getting the usage data and then throw in the wish list of what you'd LIKE to have in there, like the Espresso Machine and heated cat blanket and MargaritaMaster 9000 and see what it says. Then start whittling down and see where the sweet spots are. Once you have that you can start trying to find the hardware to meet your budget. Somewhere in the middle they will meet up. :)

Yes, it's a LOT to think about, but it's SSSOOO much cheaper than being one of those "I bought all this stuff, how do I make it work?" people.
 
I will add that electrical consumption varies greatly from person to person and house to house and season to season.
My family uses ~12000 watt hours per day in the winter and ~20,000 watt hours per day for the summer.
The difference being air conditioning.
 
Hi, I am after some advice as i am new to any sort of electrics and I am trying to get all the confusion sorted into common sense , yes I have watched hundreds of Utube videos and this is why I am confused . I have a budget of about £2500 and want a solar with 240v and 12v . My aim is to be able to use a Fridge/freezer 24/7 also need to power 2 x Cpap machines at night for our sleep apnoea they are both 60w , also charge phones,laptops,cameras and also lighting and spare storage for cloudy days . So what system would anyone advise , 12v ,24v ? A all in 1 box like a VICTRON ENERGY EASYPLUS or a Growatt or just separate components ? I cannot afford expensive batteries and just need something to give me enough power for 1 or 2 months at a time . My cabin is near Limoges in France but I live in UK . If some kind person could give me a list of products to build a suitable system that would be great . How many solar panels and what size , how to join them together also all other components including wires and sizes , what sort of wire cutter and crimper tool , also battery sizes and how many and again how to connect them together . Yes sorry it's a big ask but I am so confused . Thanks in advance .
Have you looked at portable power sytems? There's a lot out there and they may suit your needs better. https://dcguy.co.uk/plug-&-play-power-systems some examples and there are complete systems with Solar panel etc
 
Good suggestion.
A portable solution, could be perfect for the small loads required. And the temporary needs, while at the cabin.
 
VICTRON ENERGY EASYPLUS or a Growatt or just separate components ?
Any of those will do.
You just need to know the daily watthours and get enough panels to both use power and run the fridge, plus recharge the batteries in four hours of peak sun.

There isn’t a real way to even guess, but running the fridge and cpaps is wildhat guessing going to be at least 1kW of panels, probably 2kW to exceed the need by an appropriate amount.
But that could be off a lot considering we know nothing of the fridge or cpaps
 
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