Our base load has crept up, partly due to crappy design of electrical products such as hobs, oven, washing machines etc that do not have an off switch and pull 'a bit' ie waste energy all the time and partly due to using more appliances eg heat pump
As a result I decided and additional 600W would help on the east facing roof. 300W isnt much cheaper as the micro-inverter price is front loaded ie 150€ for 300W, 180€ for 600W, and panels are relatively cheap (130€) The worst is delivery at 80€, but it was a lovely pallet! 579€ including roof kit.
Opted for a Hoymiles mi600, which, unlike the competition with a similar part number (AP systems YC600 anyone?) actually produces 600W. This is a twin channel device, and the panels are 1/2 cell meaning they will produce more power on the roof which is badly shaded until 9ish summer, 10ish winter. Each panel is 370W so when it's sunny I throw away 140 watts even before it leaves the inverter, but the panels are new and keen to generate; the situation will change in few years. Panels never really generate their rated power as they get hot and inefficient, and they age.
To give you an idea, today, the old set (1180 Wc) were producing 800W on the south face at 3pm. The new panels on east face were giving 600W. If they were the same age, it would be 2/3, so around 530W.
We're not allowed to give the power away that we're not using, so it gets wasted. A real shame and I'm hoping the authorities will change their minds; it's only been 2 years ish since we're allowed to install stuff ourselves, so fingers crossed.
They are pretty heavy at 20kg, and a bit unwieldly to put over your shoulder at 1.7m x 1m. I made a lifting block and slid them up the ladder. Cardboard to protect the panel (a larger piece is better) and a couple of strops.
And don't forget the bolts at the bottom of the panels to stop them sliding off the roof rails!