5kw solar array and limit to 16amp?

[KrisWragg]

I had someone around yesterday to discuss installing a PV system for me, the discussion was mostly just an overview of technologies and different pricing such as loaning the roof and paying nothing, paying outright or paying with 5 years 0% finance.

I've done a bit of reading and know a bit more about what to ask about such as what panels, inverter etc. As my main roof is East facing the guy suggested putting a 4kw system on that roof section as well as installing an iBoost so that spare electricity goes to heating my hot water cylinder.

I've read that you are limited to 16amp without permission from the grid supplier, I was thinking that with my main roof section being east facing it would be good to put the main 4kw on that, but possibly installing an additional 1kw on the small south facing section of my roof (see attached picture)

If the inverter is limited to 16amp is it fine to have 5kw hooked up to it? It seems things start to get confusing at this point as I've read various accounts of FiT and G83 rules etc on whether its based on the peak power of the panels or the inverters output.

The guy estimated the 4kw system would be in the region of £7000 which until I know what he's installing is hard to judge on whether it's a good deal, but I know the prices have dropped quite a bit recently so it's possibly on the pricey side.

In an ideal world it would be nice to fill out the whole east, west and south roof sections as I could fit around 5kw on the east side and another 2.5kw on the south / west sections. But costs, planning permission, dealing with grid seems a hassle.

 

[Gavin A]

5kWp split across teh roofs would be no problem at all on a 16amp dual tracking inverter, we do that all the time.

 

[whinmoor]

Looking at that roof, I'd suggest installing facing east, west and south. Use a panel with embedded Solar Edge optimisers.

Ask your installer to make a G59 application on your behalf but undersize the inverter to take into account the various orientations. Could you get 25 x 265w panels (Phono Solar or Jinko) on to make a 6.625kWp system? The 5kW inverter would suffice with this.

Of course, the DNO might scupper your plan but you won’t know about that until you apply.

You could go even bigger or use two inverters. Depends a lot on usage patterns in the household.

Try and get a technical surveyor to come out - not a clueless salesman.

 

[Worcester]

Remember that at 5kWp you'll be in the 4-10kWp tariff, irrespective of the inverter output.
See discussions elsewhere if you want to know why, your tariff is based on the panels not the inverter full stop.

 

[The Solar King]

Like Gavin, we regularly do this. Here is one of ours:
http://www.electriciansforums.co.uk...68887-ef-members-installs-show-us-your-7.html
I reckon the break even point between the tariff bands is around 5.5kW, but I wouldn't worry too much due to the current excellent returns. With storage on the horizon (ie within the next five years), a larger system will be beneficial.

 

[Gavin A]

depends on the self consumption levels, but for high day time energy users I'm sure we get it to more like 4.5kWp these days. Obviously that depends on how it get's costed etc.

 

[The Solar King]

Gavin could be right with high self use. My figure is based on a typical UK household consumption profile with usage around 4000-4500kWh/a. Output of array due to angle/azimuth and shading also need to be taken into account.

This is why I run all this through Expert System Software on a case by case basis to properly assess the efficacy of any proposed installation.

 

[KrisWragg]

In the end we decided to stick with a 4kw system on the east facing roof for now.

https://www.suntrol-portal.com/en/page/KrisWragg/day

Today was our first full day and it seems to be performing pretty well, obviously it tails off in the afternoon as the sun moves over. We may look at adding a second set of panels on the west + south roof sections at a later date.

It's a shame there aren't any decent ways to store excess energy as we generated more today than we use on an average day, but obviously most of it was generated in the morning whilst we're at work. Need to start timing dishwasher / washing machine etc to make the most of it.