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revor

Solar pv batteries distance to CU

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revor

On a ground mounted solar pv array supplying a hybrid inverter and batteries housed in a suitable weather proof structure ,  is there a limit on the distance from the batteries to the consumer unit. (It is assumed that the supply cable between the batteries an CU is suitably rated)

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Murdoch

Think you need @binky

 

Where is the invertor as surely the invertor comes after the PV array and the battery, but before the CU

Edited by Murdoch

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revor

Panels, hybrid inverter, (does panel DC to AC and also AC to DC to charge batteries from grid) batteries, consumer unit. 

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Murdoch
46 minutes ago, revor said:

Panels, hybrid inverter, (does panel DC to AC and also AC to DC to charge batteries from grid) batteries, consumer unit. 

 

Interesting set up

 

Why would you charge the battery using the mains? Surely then you lose power and end up costing more?

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binky

your problem will be getting a communication cable to your meter tails, you need an amp clamp or bi-directional meter in the house which needs to talk to the battery charger - I've never seen limit on cable length, but the longest off the shelf cable I know of is 10m. In this scenario you would probably be better off with AC battery pack in the house away from the solar array. Batteries also don't like to get cold, so winter in an outdoor box would not be good for them.

Edited by binky

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revor

Thanks for that. The plan by the installer was for 2 cat 5e cables think I now understand what these are for one will be as you suggest the other I guess the other for monitoring the system and link to the cloud (I think.)  The reason for my question was that I was looking for an alternative to the Sola X batteries and inverter system that has been proposed as it all made in China and from recent and previous situations no longer think I want my money going there. I reckon I will not be alone in that thinking but time will tell. Whilst browsing possible alternatives came across Powervault and in that spec the distance to the CU is limited to 25 M. I was wondering whether that was a typical scenario in this situation for the different makes. The batteries are limited to temperature variations as you state, I think the spec on the  proposed is 0 to 35 deg outside this range will shut down. I have built a special insulated (not quite finished) small building to house the gear. My initial concern was of possible condensation on the electronics and I would have a little heater in there if needed.  I did something similar but on a smaller scale when some 30 or more years ago installed electric operated gates the control cabinet was outside and I installed a thermostat and little heater in it to avoid condensation and that worked very well. 

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binky

there are plenty of alternatives to Chinese gear, SMA / LG battery is a good combination, if a little pricey. Whatever you do buy, it's best to buy as a paackage, not all battery controllers are compatible with every battery. This does tend to make buying a pain in the neck! You could of course run long DC cables into the house. This can be achieved with standard SWA cable (ie armoured) rather than armoured solar cable which is very expensive - people forget standard cable has AC and DC ratings.  Don't try to bury solar cable, it doesn't like permanent contact with water, although it could be installed in a duct provided the duct can be kept moisture free. This would mean a single inverter/ battery charge controller in the house. Many installers aren't keen on long DC runs, but seeing as some of the solar frams I've worked on have DC runs in the order of 2/300m it's not an issue, just up cable size to suite. 

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revor

Thanks Binky, Will have a look at the SMA / LG offerings. I concluded a while ago after consulting this forum that DC underground was not a good idea particularly when I saw one installation where the installer had used SY cable underground to carry DC.  As have built an insulated weather proof housing next to proposed array need to stick to all the gear  being in there also don't have enough room in the house anyway. Looking at what Zhyphen can offer at moment.  Seems though that most battery packs have components made in China. I also want something my installer will be happy with as want him to do the job as being very local and being in a rural area important to put the business his way as his lads are also local. Has also been very helpful when I have had queries.

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binky

I've fitted a few sets of Pylon and 1 set of BYD batteries - Chinese but seem fine. The charge controller is more critical than the battery I think. BYD make most of the worlds car batteries, the electric bus Boris stood in ront of a little while ago was BYD powered. Fronius do a charge unit that works with BYD. 

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revor

Thanks binky, how many do a hybrid inverter that does both  DC to AC  and then AC to DC for charging batteries from grid rather than have to have an inverter and a charger. 

I've joined up with Octopus so hoping when I get smart meter will be able to make use of low cost electricity at night to top up and maybe eventually charge a small EV.

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binky

HYbrid id definetlu the better option, I don't think SMA do one, but check out Fronius,  Solaredge, KACO and apparently LG do a unit although - never seen one of their inverters.

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revor

Thanks binky.

Came across a UK company based in NI called Zhyphen who design and build bespoke units housed in a rack system which makes it a very flexible system. They use components from different sources and "pick the best".The only snag from my point of view the batteries are Pylon. But if the other components are non China and put together in the UK then it helps to keep more of the spend here. Still trawling through the other suggestions. The proposed system will be more expensive than the Sola x but I am prepared to put my money where my mouth is provided it is not silly. I want to keep the job with the local installer so need stuff that does not need a solar installer "tied" to the equipment. Zhyphen ticks that box. Anyone any knowledge or used them.

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binky

seen the adverts, but I know no more than that about Zhyphen. Nothing wrong with Pylon batteries, I've fitted a few sets of those. Have a look at Victron stuff, Indian but very good.

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revor

Got Zhyphen on back burner at moment it is a good set up. Have come up with another option via Aceon a UK battery specialist. An Italian inverter from Delios and BMZ battery packs from Germany with cells made in Korea. Waiting for pricing at moment.

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binky

Looks interesting, like the battery pack, looks very neat. Mind if I ask how much? 

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revor

Only just seen your posting did not see reply notification. Only just got quote anyway. 3.9K for bat 10KW and 2.3k  for inverter 6.kva. They are set up as a package. Bit pricy though compared to China stuff. Relationships are heating up with them worldwide could get messy I guess over next few weeks. If you are interested in the gear could post link to the brochures. Can only go so far in understanding the specifications have asked my proposed installer to take a look. Started looking for panels now bit more choice.

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binky

battery price is compatible with the likes of LG,  inverter seems a bit dear. 

 

Post the brochures, always worth a read. The Solar wholesalers have stream-lined stock levels over the last few years, so the range of products is much reduced and I don't 'see' many options these days. 

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revor

https://www.aceongroup.com/wp-content/uploads/2020/02/Brochure-ESS.pdf

https://www.aceongroup.com/wp-content/uploads/2020/02/Delios-Inverter-Brochure-19.pdf

I agree the inverter seems expensive but Aceon have argued it is more robust and powerful than others in same category. I am not qualified to agree or disagree. But input and output numbers are bigger.

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binky

the inverter certainly looks like  abig unit, that doen't necessarily mean it has reliable components inside, but anythng electrical works better if kept cool, so a bigger box generally means more cooling space for components. What I am less keen on is the fact it has a cooling fan similar to what your comouter has. THe inverter manufacturers I am familiar with have designed these out - check it occasionally for fluff or other debris like spider webs. 

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revor

I understand your concern re fan but I see it as an advantage in that it will help to minimise chance of condensation the scourge of anything electronic. I have built a small insulated shed to house the equipment which should help and I will put in some sensors to monitor the conditions inside. What I have not worked out yet is how much ventilation to include it will depend on how much heat is generated by the gear. if my installer happy will probably go with this setup. just need to decide on the panels. What is the situation re MCS on solar seems that panels need the certification but the inverters and batteries are not yet included in the scheme?

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binky

the inverters are usually sealed against moisture and the fan forces air over cooling fins, rather than through the electronics section itself.Most now work on 'natural convection' ie they have more cooling fins and no fan. Your right though, the fan would probably help with condensation, and as the inverter will off load some heat, probably enough to keep it dry. Ventilation for the box, i would try and make the box large and airy, vents at top and bottom, but fit vents with anti-insect mesh or you will have every spider, woodlouse and snail making it their home. 

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revor

Have now got Q- cells panels lined up the G6+ and G8+ are made in Korea. Europe is supplied from China Korea and Malaysia. Will have to settle for 340w ones the USA factory produce even greater output 450W think is the biggest.  My "box" is a mini insulated metal clad shed 2M x 1.2 x  1.4 High. No ventilation yet as not worked out how much I need but have got the vents to do it. Had a max min thermometer in there and min been 14 deg and max 25deg. Now got everything lined up to procure. (Whilst I have asked for replies to be notified, since part way through the thread not been getting them, is there an issue somewhere. Checked my spam box nothing in there.)

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binky
On 11/08/2020 at 12:38, revor said:

 Now got everything lined up to procure. (Whilst I have asked for replies to be notified, since part way through the thread not been getting them, is there an issue somewhere. Checked my spam box nothing in there.)

 

Don't know about the website, it may be playing up a bit as all things computer do!

 

Q Cells are nice panels, German cell design which they used to sell on to panle assemblers. They were bought out by the Koreans a few years ago to assemble complete panels. Buils quality is superior to Chinese and performance seems reliable/ good without resorting to expensive stuff - lot of 'bang for your buck'. 

 

LOcate shed in shade of panel array of you can, and I suspect a few eaves vents top and bottom will work fine. 

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revor

Notification working again for me. Have ordered the Q panels and Renusol ground mount system. Was looking in detail at the inverter manual and the voltage drop spec is very tight at 1 % so by my reckoning it would mean I would need a 35 mm SWA from the incoming grid to the inverter. Not going to be possible. Had been informed that 10 mm would be more than adequate.  I presume that this extract from the manual means voltage drop. The power dissipated on the line must be lower than 1% of the nominal power. There  is a table of length vs cable size  and for 6 mm it is 15 M.

Something I had not appreciate and something that I thought would need to be done as an extra is that in the event of power failure from the grid it switches automatically to battery and auto disconnects from the grid and also has facility to switch on a generator. I do not know all that much about inverters but have looked at some but don't recall this feature on any of them the only off shelf system am aware of is the Tessla back up Gateway, so makes the inverter good value after all.

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binky

biggest issue with smaller size cables is it can cause voltage to rise, so if you are near top limit on your grid supply, then it can push the voltages higher and cause the inverter to shut down.

 

I had a job where the supply is 16mm over a 110m run, the customer wasn't keen on shelling out £3k for the new cable or digging long trenches on the access track to his barn, so we fitted the system anyway.  The system was underperforming forecast, so we checked the grid voltages and they were at top limit,  so we complained to Western Power. They have since replaced the pole transformer and dropped the set voltages down to a much lower level, and everything has worked fine since. The customer now wants another set of panels on the same barn roof, which I wasn't keen on fitting, but, I calculated the resistances and the subsequent likely rise in voltages. I was surprised how little difference it made, and it would keep the system voltage well within spec, so we wil be fitting a second set of panels sometime soon. Energy dissipation was around 80/100W over the length of the cable - a light bulb basically. I doubt it would actually see that full energy loss, as the customer has a plant room about half way for his bore hole, and from this room there is also a supply to his jacuzzi, which will be programmed to take advantage of the solar.

 

So whilst we like to avoid more than 1% losses over the cable, in reality it's OK in the right circumstances. At normal 3% 16mm would be fine at 100m run

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