Micro Inverter / Optimiser Locations

[Conor]

Our build start is hopefully impending in the next few weeks... as we're doing ICF, we'll be at roof level before we know it! So I need to have a PV design sorted sooner rather than later.

 

We're using a Thermohouse EPS roof panel system - approx 250mm think EPS sheets with steel reinforcement. We'll have a narrow service void below this (max 50mm, more like 25mm), but otherwise all ceilings will be vaulted and no attic space. Panels will be mounted in a GSE in roof system.

 

We'll have 8 panels on our south facing roof, and 8 more split between east/west roofs - 5kWp total. (this is because we can only fit 8 on the main roof due to a dormer, and we've no garage roof option) So I'm likely to go with micro inverters.

 

I looks like these clip on to the panels? Can they be located remotely? E.g. in a remote location like you would a standard inverter? Or are optimisers with a central inverter a better option?

 

I'm really reluctant to have anything serviceable on the roof, as it will be very difficult to access due to balconies below and it being basically three stories up.

Edited May 28, 2020 by Conor

[Mr Punter]

Not a clue about PV but I am really interested to see the project as it progresses. Will you do a blog?

[joth]

Microinverters are convenient (maintenance wise) placed inside the loft, but should be as close to each panel as possible (ideally just using the short retained flylead that comes with each panel, no extensions). This is awkward if doing a "warm loft" as it means lots of penetrations through the thermal & airtight boundary on the pitched roof. For this reason we're doing micro-optimizers on the back of each panel, then we'll chain them to have high-voltage DC connection to the ground-level inverter.

 

 

 

 

 

[Conor]

36 minutes ago, Mr Punter said:

Not a clue about PV but I am really interested to see the project as it progresses. Will you do a blog?

 

Yes. Should have started already as we've done demolition and recovery of materials from the original house. I'll have to do it retrospectively. 

 

 

6 minutes ago, joth said:

Microinverters are convenient (maintenance wise) placed inside the loft, but should be as close to each panel as possible (ideally just using the short retained flylead that comes with each panel, no extensions). This is awkward if doing a "warm loft" as it means lots of penetrations through the thermal & airtight boundary on the pitched roof. For this reason we're doing micro-optimizers on the back of each panel, then we'll chain them to have high-voltage DC connection to the ground-level inverter.

 

 

Sounds good - after I posted I spotted micro optimisers that replace the control boxes in Perlite panels and seems like a good option. Using them brings the whole installation in at about £5.5k.

 

FYI rear view of house attached. Won't be putting the skylights in to the bedroom outshoot, so have chance to fit 4 panels on each side. Main roof with dormer faces due south. Other option is the flat roof, but I'm not sure on the aesthetics.

 

[Dan F]

Will you be using GSE integration?  If you are, their install guide talks about optimizer locations in relation to GSE unit and the panel.

 

5kW/16 = 310W?  Is it worth looking at a higher wattage panel to push this up?  Given the split between south/east/west roofs, a slightly larger install capacity isn't necesarily going to cause an issue with export, but would mean you have more generation in spring/autumn.

Edited May 28, 2020 by Dan Feist

[Conor]

1 hour ago, Dan Feist said:

Will you be using GSE integration?  If you are, their install guide talks about optimizer locations in relation to GSE unit and the panel.

 

5kW/16 = 310W?  Is it worth looking at a higher wattage panel to push this up?  Given the split between south/east/west roofs, a slightly larger install capacity isn't necesarily going to cause an issue with export, but would mean you have more generation in spring/autumn.

320w. I rounded down. Just spotted these. Any reason not to use these?

 

https://midsummerwholesale.co.uk/buy/longi-solar/longi-365

 

C

[Mr Punter]

I like the design.  It looks quite expensive and has some complicated junctions but you have obviously thought it through. Any sharing of GIA and budget (excluding service connections and fees) would be appreciated but really I am just being nosey.

[Conor]

3 minutes ago, Mr Punter said:

I like the design.  It looks quite expensive and has some complicated junctions but you have obviously thought it through. Any sharing of GIA and budget (excluding service connections and fees) would be appreciated but really I am just being nosey.

 

With the panel roof system and ICF it's quite simple. Only complicated but is a mezzanine on first floor, bit prices have come in good enough. It's 300m² and were hoping to bring it in at £850m². Bit 100m² of that is a basement that will only have a small utility and bedroom finished, rest will be bare. And there won't be a garage and the courtyard, retaining walls and covered areas are greatly paired back from this rendering. And there won't be a boat.

[dpmiller]

I had great price and service from Plug-in Solar, I think they're a reseller for Midsummer, and didn't have any issue with delivering to NI.

[Dan F]

22 hours ago, Conor said:

320w. I rounded down. Just spotted these. Any reason not to use these?

 

https://midsummerwholesale.co.uk/buy/longi-solar/longi-365

 

Don't know much about all the different panel manufactuers.  We've decided to go for panels with i) 20-25yr warranty ii) low degredation that will give around 90% after 25yrs, because we plan to live in the house for a long time and don't want to have to be replacing in the near future. (the good warranties cover all scaffolding/labor to resolve any issues).  This led us to REC and LG.  But I've heard good things about JA/Q-Cells also which have lower price point with (I think) less warranty and more degredation.

 

I'm going to look into this again though, make sure there isn't a good budget panel that is almost as good as REC.

 

 

[SteamyTea]

39 minutes ago, Dan Feist said:

low degredation that will give around 90% after 25yrs

That is about 1W_p a year on a 250W_p module.

 

What many manufactures actually do is select the best batches of modules, say the ones that are actually rated at 265W_p on the standard tests, label them as 250W_p, then charge a premium for them.  This leaves you with a 238.5W_p module, which is performing at 95.4% of the what you thought was a 250W_p module.

Trouble with this is that for a few years, your system will seem to perform better than expected, then eventually drop off.

So you may be better off just looking at slightly better performing modules, rather than ones with a warranty.

Some of the 'cheap Chinese' modules are identical to the more expensive 'USA or EU' made ones.  Thing is, they are often the same product, from the same factories, made with the same materials, on the same machinery, by the same people etc etc.

Just the testing and labelling is what sets the output, not the quality, or price, of the product.

[Dan F]

@SteamyTea I've heard BenQ AUO == Sunpower.  Any other suggestions of cheaper panels that might be good candidates to look at?

[tanneja]

@Dan F if you don't mind, in the end did you manage to select a panel that represented best value to you?

[Dan F]

2 hours ago, tanneja said:

@Dan F if you don't mind, in the end did you manage to select a panel that represented best value to you?

 

Still plan to use REC or LG rather than switch to a more value brand. 

 

The REC n-power 315W represents a good quality/value IMO at £150 retail for leading brand all-back panel and comes with 25yr product/performance/labour warranty if you get it installed by an approved supplier.   You obvisiouy get cheaper 315W panels though...