Off-grid Solar PV: What kit are DIYers using?

ciotog

Been reading for quite awhile and love the setups. So, I've been thinking about an off-grid project (home "office" / glorified shed) and I'm wondering what kit others are using and recommend. There's a spot where I was thinking 5 of these Longi 450W panels (https://midsummer.ie/buy/longi-solar/Longi-450-whi-blk) would work nicely in a ground mount setup, as a starting point. I'll almost certainly go with a Pylontech battery: While I'm impressed with what folks are doing via AliExpress, I don't have the appetite for that yet .

What do people use on the MPPT CC and inverter side of things? Obviously Victron kit features when you're researching but on here it's almost universal "over priced" when referring to their stuff

ciotog

Looking at https://www.boards.ie/vbulletin/showpost.php?p=117024871&postcount=2850 , 6 375W panels appears to be more cost effective (I was thinking about just going with the highest generating panel with a view to possibly adding more as time passes and prices come down). Space isn't really a constraint as it's rural

OTG

Not set mine up yet (plan to do so in Portugal?) but have gone for 3 separate systems for redundancy.

3 X Panels 7 x 100W in series to keep Amps down and keep wiring costs down.
https://www.amazon.co.uk/gp/product/B07S62BHTT/ref=ppx_yo_dt_b_asin_title_o01_s00?ie=UTF8&psc=1

3 x Charge controller, this allows me to run 7 panels in series and run a 24v system.
https://www.amazon.co.uk/gp/product/B07VCHTHQ2/ref=ppx_yo_dt_b_asin_title_o06_s00?ie=UTF8&psc=1

Inverters,
Got this one for my future workshop/well pump, hopefully allow me to run an air compressor and a deep sump of some kind.
3000W/6000W Pure Sine Wave Power Inverter DC 24V to AC 230V Truck Converter UK
and 2 of these for everything else
2000W 4000W Pure Sine Wave power inverter Truck converter DC 24V TO AC 230V 240V

Batteries
still not splurged on these yet but seeing as I've opted for 24v system it gives me many more options, if I'd opted for 12v I'd need to buy more expensive batteries in order to get my amp hours up. Ideally I'd get something like Trojan 6v double tops in series would be enough for my needs as 3 systems. If I was stuck I could even resort to 2 truck batteries in series and only draw from system during panel production.

Cabling
Panels to Charge controller
https://www.amazon.co.uk/gp/product/B07S93F823/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1
https://www.amazon.co.uk/gp/product/B07S96SJ86/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1
https://www.amazon.co.uk/gp/product/B00H1M8ASE/ref=ppx_yo_dt_b_asin_title_o01_s00?ie=UTF8&psc=1

Cabling Battery to Battery and Inverter
https://www.amazon.co.uk/gp/product/B00E4YO6CG/ref=ppx_yo_dt_b_asin_title_o04_s00?ie=UTF8&psc=1

Terminators
https://www.amazon.co.uk/gp/product/B00904IOWI/ref=ppx_yo_dt_b_asin_title_o03_s00?ie=UTF8&th=1

Bus Bars x 3
https://www.amazon.co.uk/gp/product/B07DN8KMTC/ref=ppx_yo_dt_b_asin_title_o02_s00?ie=UTF8&psc=1

Fuse x 2 for the 2000w inverter systems
https://www.amazon.co.uk/gp/product/B071957HDD/ref=ppx_yo_dt_b_asin_title_o02_s01?ie=UTF8&psc=1

Fuse x 1 for the 3000w inverter system
https://www.amazon.co.uk/gp/product/B071RTBJCD/ref=ppx_yo_dt_b_asin_title_o02_s01?ie=UTF8&psc=1

Circuit Breaker x 3 got the 50A version
https://www.amazon.co.uk/gp/product/B07FDX38SK/ref=ppx_yo_dt_b_asin_title_o02_s01?ie=UTF8&psc=1

This guy is very informative
https://www.youtube.com/c/WillProwse/videos

here's the 24v system I'll be following https://www.mobile-solarpower.com/2000-watt-24v-solar-system.html

Please do your own research all the above is my best dead reckoning, I don't see it going tickety boo on first attempt but as far as I can tell it should work ok. If not I can always resort to my trusty Kelly Kettle.

ciotog

Thanks so much for taking the time to lay all this out - really appreciate it

air

OTG, those panels are a terrible choice in terms of value per watt.
3 separate systems means 3 times the likelihood of failure and 3 times the standby losses.
You'd be far better off to build a single well designed system and keep a spare of critical components off line if reliability is important to you.
If you match your panels well to your battery string voltage then you can get a much cheaper PWM solar controller which will be almost as efficient and much more reliable in the longer term.

OTG

ciotog wrote: »

Thanks so much for taking the time to lay all this out - really appreciate it

Not a problem, all sitting in my Amazon orders but as AIR pointed out it's not a perfect system and I have made mistakes. Pretty sure I can run 7 panels in series with that model of Charge controller even at high temperatures (7x18v=126@25C and up to 1040Watts if 24Volt system, the Amps are low too coming off the panels so well below the 20A input limit).
Found that MPPT to be the best value for what it can deal with, it's just a massive heat sink with decent terminals and a monitor you can run somewhere handy. That guy in the video's swears by them.

The RV style setup has been used for years. Went for 3 systems so if a part goes I can take my time getting a replacement and plug my freezer in another inverter. Yes the inverters in idle mode will use 20% but just turn it off when not in use.

I couldn't find an MPPT to handle the 2-3000 watt system I'll need without buying an off the peg hybrid/grid tied mucho expensive service company/government grant endorsed boondoggle.

air

You'd be better off going 48V really, this will give you twice the power handling capacity for the same amp rating of controller.
It also halves the size of the cabling you need to use on all your DC circuits.

If you have a lot of PV, the cheapest way to utilise it off grid (as far as I'm aware) is via a grid tie inverter AC coupled to your off grid inverter.

You'll need a suitable (low frequency H bridge) type off grid inverter but it works really well then and when the sun is shining the capacity of the grid tie inverter will add to that available from the off grid one to give you increased peak capacity.

I've run this setup myself for over a year with nothing but a voltage controller switching off a contactor between the grid tie inverter and the off grid one when the batteries were full.
It worked perfectly.

harderthanf

air wrote: »

OTG, those panels are a terrible choice in terms of value per watt.

They are cheaper direct. They have an EU base and ship from Germany. I have 4 of these and all cost a good 20-25 euro cheaper when I bought direct.
They panels are "OK".


https://www.eco-worthy.com/collections/solar-panels/products/100w-12v-monocrystalline-solar-panel

air

You can buy 320W panels for not much more here in Dublin
https://solartricity.ie/module-amerisolar-320w/