Experience of 250kW installations

[SolarRoofSols]

has anyone designed and installed 250kW ground mount array? If so, would you mind if i picked your brains via pm/email? PM me if you're willing.

 

[Worcester]

Yep, I get my brain picked at £150/hr for that type of work

 

[wersolaruk]

I charge more like £250 per min, why do you need to ask advice?

 

[a1colly]

ask openly so all can gain knowledge. I've done two roof top 250kWp installs, and a 500kWp ground mount.

 

[SpitfireW'sale]

We have designed & supplied dozens of 250kWP+ systems. If you would like assistance feel free to send an email to [email protected] and we will see how we might be able to help with your question(s)

 

[pwboston]

Im going to ask a question openly as a situation has arisen.

We are quoting at the design stage of a new building for the electrics and the customer has requested (and we have verified with Local power supplies) that they want a 75kw system.

Do we have to pay more fees to the MCS or any other body to be able to do this, IE register the job etc etc. Or the NICEIC to go beyond 50KW system?

Thanks for any advice given

 

[TedM]

MCS only covers systems up to 50kW. Over that size and you are on your own.

The system has to be registered directly with OFGEM under their ROO-FIT procedure. https://www.ofgem.gov.uk/environmen...ariff-fit-scheme/applying-feed-tariff/roo-fit

 

[SolarRoofSols]

We have installed 50kW on roofs before so are ok on the G59 planning side of thing and have some idea of the labour, inverter choices and cable management etc. I was after some guidance on how this translates to a field mounted system. I.e. inverter management (external vs internal mounting, which inverter brand is most common for this size), how installers navigate cable management etc;

Roughly how much time it takes to mount the frames, any potential pitfalls people have come across etc.

The electrical side of things is being handled by a company who have a lot of experience of this scale of install on the electrical side of things, so it really is just the panel/inverter side of the planning that we are trying to sense check.

 

[Worcester]

Roughly how much time it takes to mount the frames

Varies dramatically from job to job = ground conditions, mounting frame type, access, can easily mean that the costs on one installation can be twice as much as another, It's just standard civils costing - @250kWp it would be far cheaper to get a specialist groundworks sub-contractor in than to try to do it yourself. Presumably you also need switch room housing for the inverter, grid sub-station, security, etc etc.

 

[a1colly]

As above when it comes to the ground works get the pros in. The key is to decide on your mounting system firstly; 'Y' frame, pile driven or trough sub bases. Don't forget to think about things such as weed barrier and gravel to control vegetation. If you plan on fitting string inverters on the mounting system think about security, I've visited a site recently where a 9ft electric fence was installed along with security cameras (4MW). For the size you're planning on don't use a central inverter (learnt that mistake) think about a switch/plant room but plan on heat disputation if you site all your equipment in it. As for choice of equipment that comes down to individual choice an what your client is expecting, do they want string monitoring etc. with regards to pitfalls other than getting equipment and yourself stuck in mud in the winter or sunburnt in the summer think access, your talking the best but of a 1000 panels pending size choice and you'll want to make it as easy as possible.

 

[SolarCity]

Why are you against using central inverters for systems this size? Is it down to the difficulty in running all the DC cables to one central spot?

I think central inverters can be a good option depending on the formation of the array. It also solves the issue of security somewhat.

For the OP, if you do down this route, a suitably sized plant room is essential: Concrete base designed to take the load, ventilation, suitably sized doors to facilitate wheeling in and out of inverter, concrete ramp.

 

[a1colly]

The issue with using a single central inverter on a 250kwp installation is that a fault will shut your entire plant down. I lost my last plant in the height of summer for the best part of six weeks est lost generation of £12k. Plus, the logistics of repairing them can be a nightmare, the unit we installed came in at a nice 2.75tonne and I had to strip the transformer, not done that easily.

If you utilise string inverters you only loose a percentage of your array and your end client will always be happier about that.

Other factors with central inverters is string monitoring, fuse protection, isolation. These all add up in coat and time. I ended up having 5 small huts installed to house all o the above then had to run the 50mm dc cable back to the inverter. And that was over a short distance.