Soldato
12 x 435W panels for £68.40 ex vat? seems like a great price!
Ronski's Solar & battery DIY build with whole house backup
- Thread starter Ron-ski
- Start date
Soldato
Which MPPT did you get for them?
Who are you using for panels if I may ask? Need to get some stuff ordered too.
I think I've settled on 5 panels on the side of the south facing house wall, so going to do that myself as it's ladder accessible.
SmartSolar MPPT 150/45 for the rear wall in a 3S, and SmartSolar MPPT 280/85 for the roof, which will be in a 4S3P arrangement.
Bizarrely its https://www.cityplumbing.co.uk/c/product/renewables/solar-pv/c/1870005/
Apart from the keen prices another benefit with City Plumbing is they have loads of local branches and you don't get stitched up with £100 or more delivery, so save even more money.
Nope, £68.40 including VAT, normally £70.99 but managed to get a little discount.
You can get 410 watt panel for £56.74 including VAT.
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Soldato
City plumbing i got mine from, can now get my panels for £54…unbelievable jeff lol
Back in November 2022 I paid £179 inc vat for 395w panels, very cheap now.
Soldato
Not sure if you bought them yet but I saw the 250/85 when helping someone else for only £413 inc. VAT.
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Thanks, I'd seen that, but ordered elsewhere, I'll update when they arrive.
Result! Their prices are very reasonable indeed.
Soldato
Update on yesterdays progress, it was a long day.
This is what we had yesterday morning.
The DC isolators have now gone, the two combiners boxes have been condensed into smaller ones - no need for fuses when there is only two strings combined. The MCB's in the combiner boxes are suitable means of isolation.
This is where I got to last night.
Inside the combiner boxes.
This will be the final layout, its surprising just how much bigger the 250/85 MPPT's are compared to the 150/45's.
I woke up about 5:45 this morning, so popped out to the garage to check voltages, 100v on each combiner, which hopefully means I got all the wiring correct!
There is eight black PV cables coming in, I did of course mark everything up as I disassembled it, and some was already marked. I've now marked the pairs more clearly, and put red heat shrink on the positives.
Best I go and get the MPPT's wired back in, so we can start generating some power!
This is what we had yesterday morning.
The DC isolators have now gone, the two combiners boxes have been condensed into smaller ones - no need for fuses when there is only two strings combined. The MCB's in the combiner boxes are suitable means of isolation.
This is where I got to last night.
Inside the combiner boxes.
This will be the final layout, its surprising just how much bigger the 250/85 MPPT's are compared to the 150/45's.
I woke up about 5:45 this morning, so popped out to the garage to check voltages, 100v on each combiner, which hopefully means I got all the wiring correct!
There is eight black PV cables coming in, I did of course mark everything up as I disassembled it, and some was already marked. I've now marked the pairs more clearly, and put red heat shrink on the positives.
Best I go and get the MPPT's wired back in, so we can start generating some power!
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Today's progress.
Still need to label up the combiner boxes and tidy up the wiring a bit, need to 3D print same cable clamps as well. Got two more combiner boxes to fit, and when they arrive two more MPPT's.
Still need to label up the combiner boxes and tidy up the wiring a bit, need to 3D print same cable clamps as well. Got two more combiner boxes to fit, and when they arrive two more MPPT's.
Associate
Whats the benefit of the combiner boxes with 2 strings? I understand why the fuses to each string were removed in a 2p setup and would be required when doing 3P+. Is it just because you had them you are using the MCBs as isolation? Given this is essentially what I wanted to build, I was looking at just a mc4 combiner with an isolation switch on the combined output. My combined Isc is 28.62A , so i was thinking it would be fine to go through mc4's / 6mm cable to the MPPT? Just wondering if i'm making a mistake here considering its not the route you're going down. I can't understand why I'd need any breakers on the generation side
My initial design was heavily influenced by Andy's Offgrid Garage, I'm not sure I even considered using MC4 combiners.
On my 3S2P arrays it would probably be better (certainly tidier from a wiring point of view) to use MC4 combiners on the roof, then run down using 6mm cable to a single isolation switch, but due to the layout that would also introduce more MC4 connections, and they are best kept to a minimum.
On my NW house roof array combining on the roof would cause voltage drop issues over the length wire back to the garage (estimated at 24 meters). You can overcome voltage drop by running more panels in series thus increasing voltage and reducing current, but then you run out of options with Victron MPPT's.
Once you go above 250v you need the RS 450/100 and they get very expensive, above 450v there is no option.
You don't need breakers, you need a means of isolation, so either a breaker or an isolator, I had both - the electrician insisted on isolators, when they are not needed as I have breakers.
So if combining on the roof with MC4's the main thing to watch is your voltage drop from the panels back to the MPPT.
I presume you've put your panel specs in to the https://www.victronenergy.com/mppt-calculator
Hope that helps.
On my 3S2P arrays it would probably be better (certainly tidier from a wiring point of view) to use MC4 combiners on the roof, then run down using 6mm cable to a single isolation switch, but due to the layout that would also introduce more MC4 connections, and they are best kept to a minimum.
On my NW house roof array combining on the roof would cause voltage drop issues over the length wire back to the garage (estimated at 24 meters). You can overcome voltage drop by running more panels in series thus increasing voltage and reducing current, but then you run out of options with Victron MPPT's.
Once you go above 250v you need the RS 450/100 and they get very expensive, above 450v there is no option.
You don't need breakers, you need a means of isolation, so either a breaker or an isolator, I had both - the electrician insisted on isolators, when they are not needed as I have breakers.
So if combining on the roof with MC4's the main thing to watch is your voltage drop from the panels back to the MPPT.
I presume you've put your panel specs in to the https://www.victronenergy.com/mppt-calculator
Hope that helps.
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Look what arrived today 
Not the best looking panels, but they'll do.
Not the best looking panels, but they'll do.
Soldato
Im thinking of ordering just to have them here….. 54 bucks now for 410w panelsLook what arrived today
Not the best looking panels, but they'll do.
Its hard to see them getting any cheaper, and if they do it certainly won't be much, it would also guarantee you have matching panels, and give you incentive to get on with it
Soldato
Its not the incentive i need, its the time and money lol……just got so much to do.Its hard to see them getting any cheaper, and if they do it certainly won't be much, it would also guarantee you have matching panels, and give you incentive to get on with it
500 bucks of timber came today, thats just to finish the back garden, then i need to start the front, before moving onto the new panel mount above the shed, so i can take down the old one and remove the greenhouse. To then start on the new build……its either raining or too bloody hot to do anything.
I know the problem with time, that's my major issue (lack of it), I actually did about 12 hours work on Saturday alone, and it will soon be the weather when I need to start the external work, like you say its either going to be chucking it down or absolutely roasting hot, and I need to be on the roof.
Also got a hedge that desperately needs cutting (might do that Sunday), and some landscaping which needs finishing, but that's needed doing for years, so can wait until next year (again).
We're also doing away with the gas hob, so need to get a gas engineer to disconnect it, then I need to remove it, then I need to make the hole bigger in the granite worktop, so its ready along for the electricians to wire in when they do the panels.
Also got a hedge that desperately needs cutting (might do that Sunday), and some landscaping which needs finishing, but that's needed doing for years, so can wait until next year (again).
We're also doing away with the gas hob, so need to get a gas engineer to disconnect it, then I need to remove it, then I need to make the hole bigger in the granite worktop, so its ready along for the electricians to wire in when they do the panels.
Soldato
Yup, its never ending. But my front garden is in dire need…..10yrs we been here and its never been touched as i spend all my time out the back. Will get there tho…