It's important that the PV Array is the correct size for your home

When sizing up a system (PV solar array) for a home or business, it's important that the system is sized correctly.

What this means is that there is enough solar panels producing enough power to match the energy consumption for that property.

The first consideration is whether a battery storage device will be used. If this is the case, the solar array needs to match the property's consumption over an average 24hour period (including winter conditions), catering for the day time load, as well being able to store enough energy through the day to supply the property into the evening, and throughout the night.

For this reason the PV solar array normally needs to be larger to cater for the excess energy needed for evening supply.

When a battery is not considered, the calculations are a bit different.

In this case, the only consideration is on the day time load. This amounts to all appliances operating through the day such as fridges, freezers, T.V's, computers, stereos, pool pumps, charge stations, etc.

It also includes things like hot water cylinders, and spa pools.

Having a system that's too large for a property's energy needs could be considered as an over investment in product when batteries are not installed.

When power is created from the sun using PV solar panels, if the house or establishment can’t use all that power at that time, then that excess power typically gets pushed out to the main grid supply. (considered as exported power).

For 1kWh of power (let’s just say a hand full of power), energy retailers will pay about 7 or 8 cents when that power is exported or pushed out to the main grid from the Pv solar array. For the same amount of power, when used within the property, is worth normally between 25 to 30 cents.

(This is generally speaking. Energy retailer’s prices can differ slightly, as can the prices they offer between winter and summer.)

The bulk of savings is made when we use the power being generated at that time within the home and property, (hot water storage, general power usage, appliances etc).

Conversely, when a system that's installed is too small for the property, this too can have a detrimental effect, and can chip into potential energy savings if the controlled hot water rate has been consolidated into the 24hour supply.

Most of us have a controlled rate for our hot water supply. This controlled supply is incentivised by having a reduced rate so that the lines company can control heavy loads at peak times.

But this controlled hot water rate is often consolidated to the normal 24hour uncontrolled supply to the home so that the hot water cylinder can benefit from PV solar production through the day. (This is to do with the difference in metering). 

If the PV solar array is too small for the property's day time load (including hot water being heated), then the difference in savings that would have been made on the cheaper controlled hot water rate can be lost.

It’s important that the system is the right size.

Damon Moore