Target kVP

robh71

Is there a formula or guidelines when planning to install, to know what your target kvP should be when you know your daily usage? Example if my daily usage is ~15kWh what should i plan to install? (Sorry if this is already posted as I couldn't find anywhere)

bullit_dodger

No, no real formula as such, just opinions from people, me being no different.

Personally I think it's wise to size your system to be give you a good shot of covering your consumption in March and october. If you do that, then all the months in between are automatically covered (as you will generate more in Apr->Sept) than those March and Oct months.

The reality is that winter Nov->Feb is a non-starter for Solar in Ireland. I've got one of the larger installations (8.8Kwp) and in December I wouldn't cover 1/4 of my consumption and I wouldn't even try to bulk up. Not worth it.

Look at Nov, Dec, Jan and feb for Solar as sort of a "Bonus" - it'll help reduce your bills but it wouldn't cover everything.

Generally (generally now!) an averaged household in Ireland consuming 4500Kwh a year would be fairly well suited with a 5-6Kwp system. If you plan on getting an EV anytime soon, I'd up that to 7-8Kwp if you have the roof space.

DC999

As much as 1) you can afford 2) roof can fit. Cheapest time to get more is on install day as cost of labour (roofers and sparks) is a huge % of overall cost.

We’re all going to be using more electricity in time (EVs, electric heating (house and water), gods knows what new electric devices will be invented as in use in the future..). So get what you can.

The inverter limit is ~5kW so you can size that roughly to 1.5 times in number of panels (kWp). But the installers can check that when quoting.

If you’ve an E/W split you can likely oversize more than South as both don’t get hit full on for a lot of the day. 

This one shows the output (kWh) based on size of the system (kWp and inverter size, and inverter size is the bottleneck): Boards.ie - Solar Capacity and production analysis - Google Sheets

ECO_Mental

Yep as much on as you can....simple!

You never hear people on here saying they put up too many panels🙂

There is now alright that new connection rule of the 5kW inverter so that might limit you or I think you can pay €1000 to get a bigger one (I Think)