whilst im lurking in the PV arena!

[DurhamSparky]

Have a customer who wishes to potentially have a few (6x) panels installed.
the property is NOT supplied from the National Grid.

I am not MCS registered but can i still install this system for them...?? and how would the invertor work? as don't you need A/C supply to kick it in to life??

im still reading up on it as this is new to me.

there current source of AC power is derived from a 2kw Generator.

 

[telectrix]

i don't know that much about pv, but afaik, the inverter will just need a dc supply from the panels to work. and you only need mcs to qualify for fit, which in this case does not apply.

 

[SpitfireW'sale]

The inverter normally needs both AC and DC supply to function. This is a safety feature so if there is a power cut the system will stop generating. You need an "off grid" system which uses batteries and charge controller, which will act as the AC side for the system.

Off grid can still qualify for the FIT (albeit with no export tariff) , but if your customer wants the FIT it must be installed by an MCS qualified company.

 

[Worcester]

Yes an off-grid system can qualify for Feed-inTariff, so long as installed by an MCS qualified company.

They'll need something like Sunny Island off-grid inverter) and facilities for auto cut in of batteries, generators etc.

Pretty straight forward stuff when you know what you're doing

 

[Gavin A]

can i still install this system for them...??

you probably could, but if you don't know what you're doing, then I'd suspect it will cost you far more in call backs, replacing bits of fried kit etc than you're likely to make from it.


it's going to be far harder to get right if you're not used to it than a grid connect set up, which essentially is plug and play compared to off grid.

 

[DurhamSparky]

How can they still get feed in tariff if they don't physically have a grid connection. The nearest supply pole is 1.2mile away and the 6 houses all have little gen sets and coal fires and ranges!! It's mad.

They would use solar for 1 laptop , odd light and washing machine .

The simple life !!

I understand concept and that of solar just not sure on rules and all the different kit available...

Must admit wish part p was like mcs, no registers installer no money no power !!!

 

[Earthstore]

You can receive FIT payments just for generating green energy, you do not have to be grid connected, but you can not export to the grid, so no export payments.

 

[Gavin A]

You can receive FIT payments just for generating green energy, you do not have to be grid connected, but you can not export to the grid, so no export payments.

do the DC meters exist now then?

 

[Earthstore]

No, the system produces in DC then an inverter converts it to AC, through the generation meter and then it would go to a charging unit, then to the batteries, then through a DC to AC inverter, then to the house as an AC supply.

I think I have put that in the right order, as someone else said it is a little complex and the installer would need to be MCS accredited to be eligible for FIT payments.

 

[Gavin A]

hmm. so only possible at all if they only aver use solar to charge the batteries, whereas probably 90% of off grid folk will sensibly have a mix of wind, solar and a generator for back up all of which will charge the same batteries and supply AC power through the same inverter.

 

[redmile-energy]

most off grid users who use generators to produce their electricity have existing batteries and inverters in place. The generator produces AC power which goes through inverters to be turned to DC and put into batteries, when the property needs power it draws it from DC out of the batteries and through the inverters back to AC so it can be used in the home. The generator only kicks in when the batteries go below a certain point and need recharging, the easiest way to imagine a PV system working in unison is to consider the batteries to be the grid- when there is demand in the property the PV system will be linked to a new inverter which can supply immediate AC power, the excess is inverted from DC to AC by the solar inverter but as there is no demand it gets exported to "the grid" i.e back through the existing inverters to be changed from AC to DC to go into the batteries, if there is no demand and the batteries are full the solar inverter would shut down. Victron produce a lot of inverters and their literature is very helpful- they also produce a Victron Bluesolar inverter produced exactly for this purpose. Hopefully my rambling makes some sense.

 

[Gavin A]

makes some sense, but seems a very odd way of doing it, and doubles the inverter losses when charging batteries. Maybe this isn't considered an issue any more or something, it's been a while since I worked with any battery set ups, but back then it was always the case that everything ran into the batteries, then through the inverter to be used, often with some low voltage DC circuits run directly to further reduce inverter losses etc.

 

[moggy1968]

A DC generation meter would seem to be the logical answer, does such a thing exist?

 

[Worcester]

@moggy168 Not for FIT it doesn't, FIT is AC....
@GavinA, most off-grid people know the hassles of living off-grid, so they have a mix of technololgies, wind, solar PV and thermal, generators, batteries, wood burners linked up to a thermal store etc to cover when that 'renewable' resource is available.

It's pretty straightforward stuff, though involves a lot of design and planning to balance it all.

Your alternative is to conisder yourself a boat / RV and run everything of DC with an small inverter to run the odd AC appliance. With AC appliances becoming more efficient and all the wiring etc being standard it actually amkes much more sense to design an integrated system.

 

[Gavin A]

Worcester - That's what I was getting at isn't it?

I don't see how an AC meter fitted the other side of the inverter works in this scenario, unless you've got the solar PV set up entirely separate from the rest, which just isn't the best way to do this.

I was never particularly keen on the direct DC circuits side of things fwiw, was just mentioning this as something people used to look at way back when.