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and this is the north-facing home mentioned in Gary’s video.

I’ve been bleating on about solar on north-facing roofs for ages!

- Solar panels are so cheap they’re almost free.
- You can almost certainly add a north-facing array to your existing inverter so no additional cost there.
- You get c. half the electric compared to a similar south-facing array over the course of a year. However it is in bright-overcast conditions when your north array comes into its own.

Stinsy wrote: ↑Mon Dec 23, 2024 8:59 pm I’ve been bleating on about solar on north-facing roofs for ages!

- Solar panels are so cheap they’re almost free.
- You can almost certainly add a north-facing array to your existing inverter so no additional cost there.
- You get c. half the electric compared to a similar south-facing array over the course of a year. However it is in bright-overcast conditions when your north array comes into its own.

Yes, I have 8kW north easy facing fir the winter and they do produce a good bit. The roof pitch is low enough that they produce loads in the summer, so much so that I turn them down.

I've too been harping on for years, probably since the early 2010's.

My argument is quite simple, the extra cost of PV, once you have comitted, is much lower, so the lower efficiency of non-south PV probably balances out.

Not exact, just an estimate, but if you are adding PV, then the cost of adding the same again on a non-south roof may only be +50% cost, for +50% generation, so it makes sense.*

The scaffolding won't double, the AC side work will be largely unchanged. The inverter may not need to be bigger, but even if it is, that'll probably be +10%. And so on. Definitely worth considering at the very least.

* And 50% gen from the north, is going to be the worst case scenario. In reality it will probbaly be 55%, and rising as you get closer to east/west. My WNW system is around 70% of south. PVGIS est is 679kWh/kWp pa.

I brought up the north facing array I want to install earlier this year.

The biggest hurdle by far - for me - isn't the cost of the panels and rails, it's the labour to get them installed. I've just had a second roofing company over to quote, but an 8 panel, 3.6kWp system generating 2.2MW annually will be ~£3000 installed by a roofer, and it's difficult to justify that vs the cost of IOG imports alone. By juggling exports at 15p it's more do-able. A local PV installer wanted circa £5k with an inverter upgrade.

I suppose what I'm trying to say is that retrofitted non optimal arrays are more difficult to justify at commercially installed rates for those of us with "preferential" electricity rates, unless you're prepared to do some DIY.

But just to add, most of the resistance to going bigger always seemed to be based on misleading info. Not just that panels had to be south, or East to West, but many folk would explain that you can't install more than 4kWp, the DNO don't allow more than 4kWp, installers have advised that you can't install more than 4kWp ...... and it stuck in the national narrative, or seemed to.

Mart wrote: ↑Tue Dec 24, 2024 9:31 am But just to add, most of the resistance to going bigger always seemed to be based on misleading info. Not just that panels had to be south, or East to south, but many folk would explain that you can't install more than 4kWp, the DNO don't allow more than 4kWp, installers have advised that you can't install more than 4kWp ...... and it stuck in the national narrative, or seemed to.

The "4kWp" limit seems to be a hangover from FiT days. You got a lower payment per kWh if your array was over 4kWp so a 4.1kWp array didn't make sense. However this "limit" seems to have entered installer lore and they no longer know the origins.

Additionally, there seems to be a resistance to fitting more solar than the inverter rating. Eg if you have a 3.6kW inverter it can be quite sensible to fit 6kWp of solar...

This lore - myth, really - is so obviously (to us) against the interests of the customer that I wonder if there is something else behind it.

e.g. most installs are done by small- to middle-size firms, quoting against each other - and UK consumers have been brainwashed to look for cheapest first cost and are notoriously afraid of any kind of number-crunching or technical appraisal, no matter how simple.

So if a firm quotes for fewer panels or a smaller battery or inverter (on whatever pretext) it is more likely to get them the job?

It is doubly vexing for us evangelists (or do I mean enthusiasts?) as the country as a whole and the individuals being conned are definitely not getting the best bang for their bucks. It has been said many times that the cost of the mobilisation, scaffolding, AC side won't change much and will be disproportionately high on a smaller system.

What other reasons might explain people going for half-baked installs?

Some 30p / watt NE self installed facing panels at nowty towers. On a cloudy winter day it still performs similar to a south facing panel and in June the sun rises in the NE for that 5am generation with high ramp up.