Adding a small vertical solar array to existing.

Jan 25, 2026 Last reply: 5 months ago 3 Replies

Hi All, It's been a while although I do keep an eye on the group.



Here's the new ponderance... In Nov. 2015 I had 2 Solar PV ays fitted to our house 14 x 330 watt panels totalling 4.62kWp going through a



3.8kW inverter.

To date the system has paid for it's self (£7341) and as of December it's now almost £9K in profit over install costs thanks to 100% energy utilisation and FIT payments etc.



Winter production is a bit naff, so it got me to thinking I could add another small array of 4 or possibly 5 pannels on the S.S.E. end wall of the house to bring a bit more low angle winter energy into the equation.



The existing inverter has dual string input used by both arrays so wondering if I was to add a 2nd smallinverter, whether the output of that could be wired into the same 16A breaker (perhaps upping the breaker to 20A to give a little headroom) or whether I sould try and find an inverter with perhaps 4 MPPT inputs. I'm tentatively presuming if 2 inverters are wired into the same breaker they will both adjust to the mains voltage , phase and whatever to work in sync.



I anticipate a small vertical array would also benefit from the solar energy reflected form the the Estuary during the latter part of the day during Autumn through Spring.



Any thoughts or suggestions. I tried to get DNO to approve G99 originally but he wouldn't have it, hence G98 and 3.68kW limit, but I don't think the relatively small additional array would be a significant cause for concern..



Cheers Pet


Of course.

?

No. On reflection the simplest way would be to add a second inverter thereby not going through the generation meter preserving the existing FIT arrangement as contracted.

Although I could add my own generation meter for the new inverter for persoanl record keeping.

I couldn't find the original calculator but a quick play with a 2 KWp (5 pannels)shows 1008 kWh/year. Worst being December at 8 kWh, 16 in Feb

So at todays electricity price it's save around £283 a year.

That makes best sense Theo. I'd also forgotten about the Inverter being part of the Feed In Tarriff recorded equipment so not changing anything on that side while it's working well is the best idea.

I'd originally been playing with the idea of Solar Thermal to make use of the solar coil in my thermal Store but it would be easier and simpler to wire up the lower Immersion heater in the tank to a P.V. array... but then, I'm better off using/storing that P.V. energy at 24p/kWh rather than using it to save gas at 6p/kWh. :)

It certainly seems to super-heat our lounge. I specified "solar reflective" tripple glazing for the 10M Sq. "glass wall" as the reflected sun

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Shows it as still having highest output in Summer for 2 kWp at 90 degrees and 160 degree orientation.

Month kWh

January 16 February 40 March 84 April 129 May 127 June 123 July 134 August 132 September 127 October 72 November 26 December 9

Excess power goes out through the mechanical meter then comes back in when the sun goes down. IYKWIM :) So I can imagine a 16 Amp breaker might trip under ideal conditions.

Cheers Pet.

Every unit lent to neighbours always returns home at some point in the season. :¬)

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