Just ordered all the panels and mountings for the NWW roof, delivery Friday.
I've added the prices per line.
I've added the prices per line.
Ronski's Solar & battery DIY build with whole house backup
- Thread starter Ron-ski
- Start date
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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Back in November 2022 I paid £179 inc vat for 395w panels, very cheap now.
Thanks, I'd seen that, but ordered elsewhere, I'll update when they arrive.
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.
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.
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
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.
Scaffolding going up next week, bit earlier than I need it, but they have a quiet week. Better early than I decide I need it and then they are busy.
Progress this weekend.
I've made up the last two combiner boxers, the second from the left isn't really a combiner as its only going to be a single string, but it keeps it looking neat.
The larger one combines three strings for the west north west house roof array, its is all wired up internally as much as I can for the moment, but I've run out out 35mm cable, and also 16mm cable for the rear wall string. Also the actual PV cables are not yet run in.
The MPPT's haven't arrived yet, with a bit of luck they'll arrive this week.
Got to cut the grass, and hedges, but if I get time later I need to lift one of the decking boards so I can run the PV cables under it from the house to the garage.
I've made up the last two combiner boxers, the second from the left isn't really a combiner as its only going to be a single string, but it keeps it looking neat.
The larger one combines three strings for the west north west house roof array, its is all wired up internally as much as I can for the moment, but I've run out out 35mm cable, and also 16mm cable for the rear wall string. Also the actual PV cables are not yet run in.
The MPPT's haven't arrived yet, with a bit of luck they'll arrive this week.
Got to cut the grass, and hedges, but if I get time later I need to lift one of the decking boards so I can run the PV cables under it from the house to the garage.
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Scaffolds gone up today, although the scaffolders managed to upset the neighbours 
They can do, but hoping that as I've treated the guy well looking after his vehicles for many years, he'll look after me. His workers though owe me no favours, not even sure they would have known who they were putting scaffolding up for (I was at work).
Got it cheap, as per above.
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Gas hob disconnected today, got a portable induction hob to tide us over until the new ones fitted.
Made progress over the weekend, but not a lot to show.
Made progress over the weekend, but not a lot to show.
Lots of bits arrived today.
Some PV cable and flexible metal PVC coated conduit for under the deck, and a box of clips.
Some cable clips
6mm 4 core PV cable in a single cable, the other roll is twin core 6mm.
Some PV cable and flexible metal PVC coated conduit for under the deck, and a box of clips.
Some cable clips
6mm 4 core PV cable in a single cable, the other roll is twin core 6mm.
Didn't get much done yesterday, as had some gardening to do, then out in the afternoon.
Made good progress today, although with the sun and heat it was hard going, had to rig up an old dust sheet for some shade.
Got all the conduits in (they were a tight fit), and also the first cable run in from the garage to the loft (not shown), although nothing is yet clipped in place.
The cable will go up the wall behind the drain pipe, and thus be hidden at ground level. The cables are run in flexible steel conduit under the decking and into the garage.
Made good progress today, although with the sun and heat it was hard going, had to rig up an old dust sheet for some shade.
Got all the conduits in (they were a tight fit), and also the first cable run in from the garage to the loft (not shown), although nothing is yet clipped in place.
The cable will go up the wall behind the drain pipe, and thus be hidden at ground level. The cables are run in flexible steel conduit under the decking and into the garage.
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Look what arrived today
, still waiting on the 150/45 though.Ordered four weeks ago today (its a beast!), but at £309 it was well worth the wait. It was an exceptional price even before I used the "Sign up to our newsletter and get 10% off your first order" offer
, I think they've removed that offer now though!Hopefully the 150/45 will arrive next week - they're expecting stock, bizarrely they have 5 available on eBay, but their store says available to order 7 to 10 days.
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Here's a little something I've been trying to get my head around.
The four landscape panels have four rails running vertically, the eight portrait panels have the rails running horizontally.
Now you're supposed to calculate the wind loads, the snow loads, is the roof structurally strong enough etc. Most of that is related to where on the roof the panels are located (how high, how close to the edge or the ridge), and of course the weather conditions for the geographical location for where they are installed.
As all that's a bit beyond me, Ive gone for the below - the red circles are the roof hook locations.
Now fortunately, for comparison purposes, I have a professionally installed and MCS certified installation on the other side of the roof, its been there since 2015. Looking at the hook spacings, and end of rail overhangs, I'd say its very unlikely to comply with the requirements, but its stood the test of time, and some pretty strong winds. At the time of installation, I did have to get the installer to alter one length of rail as they had a join in the wrong place - the length of rail was only supported by one roof hook. I'll have more roof hooks, and closer together, so will be much stronger.
As you can see, I have the benefit of going up in the loft and accurately drawing my rafter locations, and thus being able to work out the ideal locations, now the only variable is the positions up/down the roof for each roof hook & rail, which is dictated by the roof tiles.
The four landscape panels have four rails running vertically, the eight portrait panels have the rails running horizontally.
Now you're supposed to calculate the wind loads, the snow loads, is the roof structurally strong enough etc. Most of that is related to where on the roof the panels are located (how high, how close to the edge or the ridge), and of course the weather conditions for the geographical location for where they are installed.
As all that's a bit beyond me, Ive gone for the below - the red circles are the roof hook locations.
Now fortunately, for comparison purposes, I have a professionally installed and MCS certified installation on the other side of the roof, its been there since 2015. Looking at the hook spacings, and end of rail overhangs, I'd say its very unlikely to comply with the requirements, but its stood the test of time, and some pretty strong winds. At the time of installation, I did have to get the installer to alter one length of rail as they had a join in the wrong place - the length of rail was only supported by one roof hook. I'll have more roof hooks, and closer together, so will be much stronger.
As you can see, I have the benefit of going up in the loft and accurately drawing my rafter locations, and thus being able to work out the ideal locations, now the only variable is the positions up/down the roof for each roof hook & rail, which is dictated by the roof tiles.
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Have now got both cables run from the garage to the loft, still one more cable to run in, but that's for the panels going on the back wall, should get that done tomorrow.
Seems I overestimated on the four core by about 4 meters, still I'd rather be over than too short.
These cables will be pretty much hidden by the rear wall panels, and the cables come up from under the decking behind the downpipe, so are not seen at ground level.
Seems I overestimated on the four core by about 4 meters, still I'd rather be over than too short.
These cables will be pretty much hidden by the rear wall panels, and the cables come up from under the decking behind the downpipe, so are not seen at ground level.