What size Inverter ?

[The Smiths]

Hello All

So ive decided to go for 4 x 545 Watt Panels on my shed and am now looking at a grid tied inverter. I was under the impression that when calculating inverter size is was a simple matter of multiplying the number of panels by the panel size, then picking the next round number sized inverter. In this case 4 x 545 = 2,180 Watts So a 2.5Kw inverter is what I need. Someone told me I could get away with a 2KW due to the fact as I'm never going to get 2180 Watts due to inefficiencies and inverters have a margin of error as well.

Who's right ?

Thank you again

 

[binky]

Either will work well enough, but I think I would go for the smaller unit as you don't tend to get max outputs that often. Having said that, it's irritating to have the inverter chop the output when you do.

 

[The Smiths]

Fair enough, so I guess I wouldnt kill a 2kw it would simply max out if conditions were perfect etc.

I did wonder as my setup is so small whether to not bother with an inverter at all and just have a couple of micro inverters instead ? Is there much difference in that option ?

Thanks again

 

[binky]

your only problem with micro-inverters will be finding a unit that works without having to buy a 'hub' of some sort, so cost tends to be higher than a single inverter.

 

[Badger]

your only problem with micro-inverters will be finding a unit that works without having to buy a 'hub' of some sort, so cost tends to be higher than a single inverter.

I agree the cost is slightly more in outlay but the benefits out weigh that imho because of the single point of failure pov

 

[binky]

I agree the cost is slightly more in outlay but the benefits out weigh that imho because of the single point of failure pov

Depends on how accessible they are when the microinverter fails. Ok that should be in 20 odd years time, but if scaffold is £600, does the benefit outweigh additional cost? Generally I would only recommend fitting them on easy access roofs or where you do have a shading issue. Panels should last 30+ years, but again, in 20 years time, they may well be twice as efficient as they are now, so it might be cost effective to replace the whole array. Only time will really give us an answer.

 

[The Smiths]

I wasnt aware of hubs for microinverters ? Still very much learning. Do they not simply daisy chain into each other and then (in my case) into a 13A Socket ?

Very valid point about roof access and scafford etc - In my case however its only a shed roof so its very easy to hop on to sort any issues out.

 

[binky]

I wasnt aware of hubs for microinverters ? Still very much learning. Do they not simply daisy chain into each other and then (in my case) into a 13A Socket ?

some will work without, but whatever you fit needs to be G98 approved for grid tied operation. It's never obvious if a microinverter will work without the hub, the blurb always harps on about individual panel monitoring via the hub.

 

[The Smiths]

Are their some which arent G98 approved which I need to made aware of ? I would have thought that all of the gried tied inverters / micro inverters would be by default G98 approved ?

This will be a self install (by me) so I will complete the G98 paperwork after install and send that off to the network operator.

 

[Badger]

I wasnt aware of hubs for microinverters ? Still very much learning. Do they not simply daisy chain into each other and then (in my case) into a 13A Socket ?

Very valid point about roof access and scafford etc - In my case however its only a shed roof so its very easy to hop on to sort any issues out.

i was under the impression that all solar should be wired direct to its own rcbo/mcb setup. and have a proper isolator system double pole. not wired via a plug top or fused spur.

 

[binky]

i was under the impression that all solar should be wired direct to its own rcbo/mcb setup. and have a proper isolator system double pole. not wired via a plug top or fused spur.

That is correct, although when I first went into solar, connecting into the upstairs ring main was considered acceptable practice. That didn't last long, and installing solar on its own circuit became the norm. You used to see quite a few small plug in solar systems for sale to, on eBay and the like. But they would never comply with MCs for the FiT payments, so seemed to dusappear, although I'm sure you can still buy them if you look around.

 

[The Smiths]

Thats interesting, on my particular (proposed) setup I was intending to have the following:

1 x 545Watt Panel (with microinverter) on my log store, I have a power socket in my log store (from the shed) which also supplies some outdoor sockets in the garden, handy for cutting the grass or occasional power tools etc. I was intending wiring into this by either a fused spur

4 x 545Watt Panels with a regular grid tied inverter on the shed roof, I have a distribution panel in there (fed from the main house) and some spare slots I was going to use dedicated to the inverter

I realise its all a bit fragmented but was looking to get the most out of available roof space

Am I heading for trouble doing things this way ?

 

[binky]

Are their some which arent G98 approved which I need to made aware of ? I would have thought that all of the gried tied inverters / micro inverters would be by default G98 approved ?

The compliance is in the hub, I think. Having said that, I doubt they would be working without a grid connection, but it's something to bear in mind.

 

[binky]

Thats interesting, on my particular (proposed) setup I was intending to have the following:

1 x 545Watt Panel (with microinverter) on my log store, I have a power socket in my log store (from the shed) which also supplies some outdoor sockets in the garden, handy for cutting the grass or occasional power tools etc. I was intending wiring into this by either a fused spur

4 x 545Watt Panels with a regular grid tied inverter on the shed roof, I have a distribution panel in there (fed from the main house) and some spare slots I was going to use dedicated to the inverter

I realise its all a bit fragmented but was looking to get the most out of available roof space

Am I heading for trouble doing things this way ?

Should work fine. If your log store is close to the shed, it might be worth looking at Solaredge or Enphase, as either of these treats panels as individual power inputs, or you could look at Tigo optimisers.

 

[The Smiths]

Should work fine. If your log store is close to the shed, it might be worth looking at Solaredge or Enphase, as either of these treats panels as individual power inputs, or you could look at Tigo optimisers.

Its not as it happens, and just to make things even more interesting they are both on different angles and different orientations, the shed faces South (or near enough) and the log store faces West (so not ideal but you get what you get.

Thanks for all your much appreciate advice.