solar shed project !! wiring diagram

[mprice109]

Untitled

• mprice109
• 23 Aug 2014
• 1

hi everybody

Im no electrician so any comments would be greatly appreciated .

am i on the right track with this wiring diagram ?

it's for my garden shed its basically to get lights in there but i eventually plan to put a fridge or freeze in and a couple of sockets .

is it safe to use ?
are the fuse ratings ok or should they be lower ?
was thinking 3amp lights , 5 amp fridge/freezer and 10amp sockets

thanks in advance

mark

 

[ericmark]

With a 1000W inverter why use a 10A fuse 5A is maximum output. Having used a 3kW inverter with 6kW peak on three 160AH batteries at 12v the cables have to be rather large in your case looking at around 100 amp so needs around 25mm² cable also battery size is really not big enough for 100A drain so I would want to go to 24v or 48v to reduce current used on extra low voltage side.

The controller measures the battery voltage and using battery at same time as charging battery can mess up the controller. It does depend on how the controller charges the battery. There are two methods. One it charges battery then stops for few seconds and measures the rate of voltage drop this type seem to work OK when using battery at same time as charging. Second type measures battery charge current and switches to float once it reaches around 5 amp this type can over charge the battery if power used while charging and it has not reached the float stage.

Since your controller is designed to auto switch on lights when the sun light fails it may not be pulse type.

Also remember with more than one item on the low voltage side (230) you will need an earth and a RCD on the supply to sockets. I would not use same box with low voltage and extra low voltage fuses.

With one output only the inverter works like a shaver socket and the isolated supply is reasonable safe without an earth or RCD once you have 2 or more items fed from the inverter then earth and RCD is required.

Also if this is in a garden attached to a dwelling Part P may be a problem. I would have to re-read when not supplied from house not sure if required or not. It would be required to notify if supplied from house.

 

[JohnD]

I don't understand a 40W panel supplying a 700W fridge.

 

[bernardgreen]

I don't understand a 40W panel supplying a 700W fridge.

Simples. 20 hours of bright sunshine will provide one hour of cooling.

Well maybe half an hour as the over all efficiency of the system as drawn id going to be about 50%

Better and cheaper option would be a ELV ( 12 volt ) fridge connected diretly to the solar panels. 12 volt lighting from the battery.

 

[ericmark]

I don't understand a 40W panel supplying a 700W fridge.

Yes missed that in the main the mark/space ratio of a freezer is around 1/3 so since the panel will not work at night and also will not give 40W at all times then looking at more like a 1000W panel.

This again raises problems with cable sizes with 12v again think 48 volt is a better extra low voltage system. This will also mean the FET will better load share in the inverter so less likely to get expensive blue smoke.

However a 700W fridge is rather a large unit. My fridge/freezer which is over 6 foot tall uses 48W on run. To use 700W it would be size of a shed walk in type.

As to how a fridge would start with an inverter not so sure? Both my fridge/freezer and freezer are inverter control this is purely a soft start motor runs at constant speed but the start up watts is 261 with a non inverter freezer likely the start watts would be much higher.

I would guess you would need to double solar panel size for most fridges. Also again mine with inverter control has power factor of 0.99 but without power factor could be down to 0,75 and also not sure how non inverter fridges would run on simulated sin wave? I am told with inverter control no problem but not tried it.

Found data on non inverter fridge/freezer used 2259W on start with 82W run which could be a problem when running off an inverter.

 

[davelx]

at 240V AC there is no +ve and -ve , they are live and neutral.

I wouldn't put the low voltage fuse between the charge controller and the battery bank in the same panel as the 240V fuses - keep the ELV (12V) and LV (240V) apart. It's common to use an in-line fuse for the charger. I'd wire the 12V in red/black and the 240V in brown/blue

Rather than fuses, I'd think about a small consumer unit with normal MCBs for the 240V circuit protection. However, you need to look again at the fuse/MCB sizes. With a 1000W inverter you are never going get a very high fault current - I'd think that the inverter will shutdown well before any of those fuse sizes you proposed will blow.

It's debatable if even a 6A type B MCB would pop with a direct short, though a 3A one might (depends on the instantaneous load characteristics of the inverter). If you do want to uses fuses then you need to look at the fuse curves to be sure that they will blow under a short circuit fault but not when your fridge, etc, starts up (and as ericmark says, you need to check the start-up requirements of the fridge to be sure that the (small IMO) inverter can handle it. I think you should be looking at 12V caravan/marine fridges - remember that you waste 20% of the power by using an inverter as they are only about 80% efficient.

What about CPCs (earths) and RCD protection for the 240V side?

 

[mprice109]

thanks everybody for your replys

the power inverter is a 1500w with a peak of 3000w sorry forgot to update drawing oops ( it has a 40 amp fuse on the back of it )

as for the low voltage concerns is this not all 240v ? ( apart from the battery ) as there is no load on the charge controller everything is run off the power inverter is this ok ?

typical fridge or freezer is about 700w isn't it ? and actually work for about 3 / 4 hours out of a day ?

the charge controller is only controling the state of the battery ,ie keeps it topped up from the solar panel (acts as a trickle charger i think )

do i need a main switch/rcd before the fuse panel and after the inverter ?

thanks again for your comments

 

[davelx]

as for the low voltage concerns is this not all 240v ? ( apart from the battery ) as there is no load on the charge controller everything is run off the power inverter is this ok ?

You show a 25A fuse between the charge controller and battery +ve - that is ELV that is the one you should separate from the others which are at 240V.

do i need a main switch/rcd before the fuse panel and after the inverter ?

Yes, I'd use an RCD - and you need to take a CPC (earth) from the 240V neutral of the inverter (i.e. BEFORE the RCD - some inverters connect their chassis and output socket earth pin to neutral anyway), to feed to all the 240V accessories and equipment.

 

[JohnD]

the power inverter is a 1500w with a peak of 3000W.

Why, with a 40W solar panel?

 

[JohnW2]

the power inverter is a 1500w with a peak of 3000W.

Why, with a 40W solar panel?

Well, it's obviously the battery, not the solar panel, that will be powering the inverter, but the whole idea seems pretty unrealistic (numerically, not conceptually) - I would not think that the OP is going to get 1500W (or even 700W) (plus a lot extra for inefficiency) out of the battery for significant periods of time, even if the battery started fully charged - and it would then probably take 'for ever' for the 40W panel to recharge it, particularly in winter! ... at least, that's how it seems to me

Kind Regards, John

 

[mprice109]

to run a mains fridge i need more batteries then ? (more amp hours ) as this system will drain to quickly and the panel will not recharge it quick enough is that correct ?

only started this project to put lights in the shed so bought everything a little bigger than i originally intended . just wanted to make sure it has a little bit of room for expansion . so it seems like the fridge maybe pushing it a bit

regards
mark

 

[davelx]

to run a mains fridge i need more batteries then ? (more amp hours ) as this system will drain to quickly and the panel will not recharge it quick enough is that correct ?

only started this project to put lights in the shed so bought everything a little bigger than i originally intended . just wanted to make sure it has a little bit of room for expansion . so it seems like the fridge maybe pushing it a bit

regards
mark

You need more battery and bigger panels - if the output from the panels is less than the total power consumption, then eventually the batteries will run flat. Remember, ALL the power to run the shed is coming from the solar panels, the batteries only smooth out the load by storing excess power from the panels when the sun is high and bright and the load is low, and supplementing the power from the panels when light level are low or at night. or when the load is greater than the panels can supply at any give moment.

 

[JohnW2]

to run a mains fridge i need more batteries then ? (more amp hours ) as this system will drain to quickly and the panel will not recharge it quick enough is that correct ?

I would have thought so (and a much larger solar panel) IF the load you are talking about really is anything like 700W.

only started this project to put lights in the shed so bought everything a little bigger than i originally intended . just wanted to make sure it has a little bit of room for expansion . so it seems like the fridge maybe pushing it a bit

What you are proposing is more than adequate (probably way 'OTT') for just lighting. One thing to be aware of is that the great majority of fridges/freezers are not suitable for use in a shed in the UK, since they may stop working if the ambient temperature falls to close to, or below, freezing (0 °C).

Kind Regards, John

 

[mprice109]

all items bought on ebay brand new and haven't spent £100 yet !!! thats for everything so got the best components for my money ,and still room to expand with this setup.

the solar light sets on sale seem rather expensive for what they are offering so im still happy

thanks for your help everybody

 

[JohnW2]

all items bought on ebay brand new and haven't spent £100 yet !!! thats for everything so got the best components for my money ....

I hope for your sake that you're right, but I'm not sure that necessarily follows

the solar light sets on sale seem rather expensive for what they are offering ...

Yes, that's probably true.

Kind Regards, John