Run house off batteries during the day, no solar.

[Gareth J]

That's an old sma sbxxxx inverter. The "xxxx" part if the model number on the data plate is the max power. It's old now but still a quality European inverter. I'd use it if capacity is suitable. I've a few spares for this if you find yourself short of connectors or brackets etc.

If you do decide to get a new one, I'd offer something to buy that sma if it's sb2500 or bigger.

The roof space on your shed would be very tempting for me.

Re. MCS, there is a halfway house. It's legit for you to buy and install your own system and do everything except wire up the AC side - farming that out to an MCS registered electrician. Finding one ok with doing this is not typical but is doable. I did it a couple years ago. My normal electrician put me onto him.

 

[drjim]

If you have something to make a ground mount from you can have it up and running in no time, just need to find the motivation!

 

[Roger440]

That's an old sma sbxxxx inverter. The "xxxx" part if the model number on the data plate is the max power. It's old now but still a quality European inverter. I'd use it if capacity is suitable. I've a few spares for this if you find yourself short of connectors or brackets etc.

If you do decide to get a new one, I'd offer something to buy that sma if it's sb2500 or bigger.

The roof space on your shed would be very tempting for me.

Re. MCS, there is a halfway house. It's legit for you to buy and install your own system and do everything except wire up the AC side - farming that out to an MCS registered electrician. Finding one ok with doing this is not typical but is doable. I did it a couple years ago. My normal electrician put me onto him.

Hopefully the invertor is suitable as it was wired to the array on the building it was on. Never actually used, but part of the system.

Sadly, the roof space is mostly useless as there a big bank of 30m sitka spruce directly behind it, on the south western side. No sun on the roof after about 1pm. Ive got a 5 acre field, so much easier to just plonk it there. With the advantage its on the ground. Not 6 meters up!

Noted on the MCS. Thanks.

 

[Roger440]

If you have something to make a ground mount from you can have it up and running in no time, just need to find the motivation!

Motivation is no issue. Theres money to be saved. Time on the other hand..............................

 

[drjim]

Have you got materials to build with. That's always the issue I have. Maybe you could chop down some of those Sitka, plank them up with an Alaskan mill and build the mount from locally sourced timber. I suspect I wouldn't be the only one coming to play for that one!

 

[Roger440]

Have you got materials to build with. That's always the issue I have. Maybe you could chop down some of those Sitka, plank them up with an Alaskan mill and build the mount from locally sourced timber. I suspect I wouldn't be the only one coming to play for that one!

The Sitka are not mine.

Ive got lots of stuff, but decent timber posts i dont have. Ill have to buy some. Minor inconvinience compaed to £700 on cable

 

[drjim]

Looking at the pictures of your workshop earlier in the thread, can you not build the array on the ground in front of it rather than 150m away?

 

[Gareth J]

Iirc, the biggest those inverters went to in that shape is 3000W. £700 worth of cable seems a big investment for a relatively small array...

 

[Roger440]

Looking at the pictures of your workshop earlier in the thread, can you not build the array on the ground in front of it rather than 150m away?

The picture gaz posted is looking roughly south south west. So spring and autumn, its still shaded there by the trees in the afternoon. Plus its essentially the "garden" and would by right in your eyeline looking out of the house. (its not an overgrown shables any more) I cant go any further left, as just out of shot is a big lake!

I need them out of sight for asthetic reasons.

 

[Roger440]

Iirc, the biggest those inverters went to in that shape is 3000W. £700 worth of cable seems a big investment for a relatively small array...

True, but can always add to it later.

Little in the way of options though. Those trees really dictate it, along with the layout of the place.

 

[drjim]

Buy the cable, fit the existing stuff, already paid for. Then add more later.

Biggest cable you can get so you can fill the whole field with solar in the future!

 

[brightspark]

No doubt the de-humidifiers are the killer. I could get rid of, or massivly reduce their use, if i insulate the roof, but, frankly, thats not remotely affordable.

my roofs well insulated but i can still get a gallon a day out of dehumidifier that does 11 rooms

 

[Gareth J]

True, but can always add to it later.

Little in the way of options though. Those trees really dictate it, along with the layout of the place.

Fair enough. Remember that there is a recommended maximum voltage drop for working inverters. Iirc 1-3%. Most of the time they are put really close to the incoming supply.

Which might mean it's more practical to run the DC back to the meter building than to have the inverters out in the field. Will make future proofing upgrades harder though, unless you run unused cables for future "strings".

 

[jmp49]

I was going to chime in about the power loss with relatively higher voltage 230v ac lower than with low voltage max 60v dc from the panels that my own inverters use, so it would be better with the longer runs on the ac side and running out thicker diameter conductors to cope with capacity expansion and reduce loss in the line...
But I just looked up the specs for those sunnyboy inverters, and depending on size, they run at from 100-320vdc for the smallest one, and 268-400vdc for the largest 3200w inverter in the range, and higher voltage dc always beats ac in terms of line loss, as there's no inductive skin effect on it.
Probably easier on a practical note to find a big reel of SWA in suitable diameter for the loss/length/future expansion for a AC connection than run masses of dc cables out there though.
My furthest away inverter has about 140m of cable back to the main panel, and that's the better performing one of the two. Its just done with normal 2.5a loose cables in a buried protection conduit with some air gap for the last 40m or so once it exits the furthermost outbuilding and crosses the yard. But seems to work ok.

 

[Gareth J]

String voltage can be pretty high - up to 500V often. And ordinary PV designed DC cable is relatively cheap.

But in this case, if you're planing a future expansion, if running DC, you kind of need to anticipate now how many strings and at what power you're going to aim for while putting cables in.

An alternative might be to look into micro inverters. I don't know if they're more flexible wrt voltage drop

 

[Roger440]

Finally got the invertors out. These are the pics

The yellow one:

And the other one:

Thoughts as to why theres two. Or which one i should use? Or are they for different things.

 

[Gareth J]

Finally got the invertors out. These are the pics

The yellow one:




View attachment 484953

And the other one:

View attachment 484955

View attachment 484956

View attachment 484952

View attachment 484954

View attachment 484957

Thoughts as to why theres two. Or which one i should use? Or are they for different things.

There are two because they are only single "string". Probably because they're older. So, the array is connected in series or "strings", until the voltage limit of the inverter is approached (or some other limit; physical space etc). To have a bigger array, you start a second, or third etc loop and have another string. Obviously each string has its DC cables run all the way back to the inverter.

A newer inverter would probably have capacity for both strings together.

How many panels? I'd guess about x14 totalling about 3.5kW?

 

[GRW]

Is it an option to take AC out close to the Solar & back to the building? I.e. minimise the DC heavy cabling by covering the distance between PV & Building in much smaller, cheaper cable?
(I realise this means needing some kind of weatherproof enclosure for the Master Inverter).

OR.... I note one of the Inverter larks states its PV Grid Tied?? Does that mean DC or AC grid tied?

SMA "AC Grid Tied" inverters would invert to AC and synch with the Local AC Network - with a Master Inverter hooked-up to battery store, & a Slave on PV / Wind. The inverters synced in 230vac so you only needed local short distance DC cabling from a DC source to its local Inverter.
Are such AC Grid Tie systems still available?

 

[Gareth J]

Is it an option to take AC out close to the Solar & back to the building?

There and back?? That's not how inverters work.

I.e. minimise the DC heavy cabling by covering the distance between PV & Building in much smaller, cheaper cable?

The DC cabling requirment is smaller and cheaper as voltages are higher.

OR.... I note one of the Inverter larks states its PV Grid Tied?? Does that mean DC or AC grid tied?

Means AC grid tied.

SMA "AC Grid Tied" inverters would invert to AC and synch with the Local AC Network - with a Master Inverter hooked-up to battery store, & a Slave on PV / Wind. The inverters synced in 230vac so you only needed local short distance DC cabling from a DC source to its local Inverter.
Are such AC Grid Tie systems still available?

Not sure what that means but I think you're getting towards talking about hybrid inverters? That have capability to charge/discharge batteries and accept DC from PV. Neither of those inverters are hybrid ones.


Sorry to pick apart your post, it just, to me, reads as really confusing for the OP.

 

[Roger440]

There and back?? That's not how inverters work.

The DC cabling requirment is smaller and cheaper as voltages are higher.

Means AC grid tied.

Not sure what that means but I think you're getting towards talking about hybrid inverters? That have capability to charge/discharge batteries and accept DC from PV. Neither of those inverters are hybrid ones.


Sorry to pick apart your post, it just, to me, reads as really confusing for the OP.

Its all confusing.

Still dont fully understand what "grid tied" means?

With DC cabling i would need to puts lots in to future proof. V one 6 or 10 SWA cable. I like the idea of not having 240v equipment out in the field albeit undercover. Its going to get damp, very damp.

So cabling aside, do i have everything to connect this up?