gENI CHANGE OVER SWITCH

[beaver74]

Hi all

have been aprouched to install a small suit case Geni to a house with P.V.
the suit case is to run lights and a boiler but my concerns are with the P.V supply back feeding through the geni.the customer said he will be turning of non essential circuits but I have heard than before.

my question realy is will the P.V 1st will the inverter be damaged by the geni's unsmoothed sin wave ect
2nd will the inverters produced voltages produced by day time use damage the geni
any advice please

 

[snowhead]

You don't need to rely on the customer turning off non ess.
Put the boiler and lights on a separate garage type C.U and just change that over for Genny use.

 

[beaver74]

good point
does any one know about all p.v side of thing though for future use

 

[pvman]

I think that the inverter will stay off and show a grid fault due to the sine wave not being smooth enough, this is only a guess as I've never tried it. Lots of farms have backup generators wired in and we always install grid side so the inverter won't run when the generator kicks in.


Tom

 

[snowhead]

If it's a suitcase generator, the Inverter may not like the irregular supply, but if it's a large well regulated generator it won't see any difference.

 

[Worcester]

If it's an automatic change over switch, the PV should be installed 'upstream' of the switch, so will be isolated form the Geni.

i.e both the Grid and the PV should be isolated from the Genny when the automatic chnage over swith cuts in.

 

[infinity]

What would be wrong with the PV generating when the mains fails? as long as its isolated from the grid?

 

[beaver74]

thanks for the info lads
I think I will have a shuffle around with the existing board and have PV on CUT OUT side of change over switch Fused down)
my other option is to have a seperated 2way board fed from the common side of a change over switch and feed 1 side fron a feed from the existing main and a supply from the geni on the other,thus when the change over switch is turn the light,boiler are seperated from existing

 

[Worcester]

What would be wrong with the PV generating when the mains fails? as long as its isolated from the grid?

The the installation is not G83 or G59 compliant, and can't be certified as such. In fact part of the installation process requires you to carry out precisely that test, however as an MCS Certified installer - you know that

 

[infinity]

The the installation is not G83 or G59 compliant, and can't be certified as such. In fact part of the installation process requires you to carry out precisely that test, however as an MCS Certified installer - you know that

Yes, but if the back up system is completely separate from the grid/ mains then surely that wouldn't be a concern? It cannot feed back into the grid once its switched across?

 

[Worcester]

It gets complicated... FIT rates Grid connected / not grid connected for one, let alone the elctrical side: How is the voltage, phase / frequency signalled to the inverter to latch on - you need sunny island or something similar. The Genny (as specd) almost certainly won't meet the required standards harmonics, stability....) and in practice you'll likley fry the inverter
All proper back up systems isolate the inverter from the genny to charge batteries, so It goes - 1) Mains, 2) Batteries, (PV supoported, untill the combination can't provide tghe required power) then 3) Genny, PV isolated to recharge batteries. Sunny Island with Sunny back up do all the controlling according to certified parameters.

 

[infinity]

Yes i see now. We installed a system last week with 4x 100A lithium batteries on back up, with manual change over and PV will work in day time charging batteries so the house could probably go days without mains in the summer. Customer wanted to protect himself from 'imminent up coming power outages' :s