“What solar do I need?”
You’ve paid your last power bill and see the $$$ leave your account.
You’ve seen new solar systems pop up every week on roofs in your neighbourhood.
You’ve read articles talking about the international shift towards renewable energy.
You’ve heard the emerging talk about solar.
Now.
Now, you’re at the stage where you want to put up a solar system on your own roof but might have no idea what solar system you need.
Where do you start?
Find your WHY.
It seems obvious, but it could make a big difference to the design of your solar system.
Your WHY is the building block for designing an effective solar system tailored to meet your objectives with solar.
Do you want to:
live more self-sufficiently?
be more resilient to power cuts, due to regular outages from weather events and traffic incidents in your area?
cut your power bill down?
be present with the latest housing trends?
live a more sustainable lifestyle?
Your WHY is where you start. Once you have identified your intentions with installing solar, there’s one more piece of information you need to look at. Your power bill.
What your power bill can tell you.
If you are on a “time-of-use” rate:
You can see how much power you use at various times of the day. It is the most accurate for sizing solar.
If not,
Do you have a day/night rate?
Day/night rates show a breakdown of how much power you are using during the day, and how much you are using at night. This helps determine what loads are viable to use your solar power for and what size loads you have in general.
If not:
We calculate an informed power usage estimate based on your power bill figures, looking at the types of appliances you have in your home. Solar works best for you when you know what your generated solar energy is powering.
An apartment can use twice as much power as the identical apartment beside it.
Power consumption is extremely localised, and needs analysis if the system is to work to get you the most bang for your buck.
Your power bill can give solar system designers an indication of the size of the array you would need; your WHY will give an indication of the orientation, type, and connection of the solar array on the roof, as well as how it is connected to your home. e.g. batteries, hybrid, off-grid, etc.
Let’s look at some scenarios.
Scenario 1.
You’re living in suburban East Auckland with a large roof facing North, and a large roof space facing West. You work from home. You’ve just bought an electric vehicle that you intend to use to drop off and pick up your children from school and to run daily errands. A large portion of your large West-facing roof is constantly covered by the neighbour’s house at most times during the day. You have gas hot water and you regulate your home’s temperature constantly with a reverse heat pump during the year.
Our immediate analysis:
Because you spend your time at home during the day, the best position for your solar system is North-facing. Utilising your solar power in your home is more effective at lowering your power bill than injecting the solar power back into the grid.
Charge your vehicle during the day. Batteries are still expensive, and haven’t quite come down to an economical price for most people. There are so many brands out there that it's possible the brand you purchase now won’t be able to provide you warranty support a few years down the track. Until the day comes when the price is right, use your solar system smartly and use power when the solar array is generating. You can always add solar panels and/or batteries later.
You can nurture the idea of putting solar on your West-facing roof space to compensate for your afternoon power usage. However, we are extremely passionate about not devaluing your home. Putting solar on only the section of the West roof that is not shadowed could look strange, and could undermine the aesthetics of your home.
Scenario 2.
You’re living in suburban East Auckland with a large roof facing North, and a large roof space facing West. You take the bus to work and drive a petrol car to do your errands. Because your work away from home, you tend to use the most power during the early and late hours of the sun-day. Because you don’t have a gas califont, your home’s hot water is solely heated by electricity. You’ve seen your neighbours install solar and hear them buzzing about how amazing it is to complement the new electric vehicle they have just purchased at the start of the year.
You’re skeptical that solar won’t meet your needs in terms of saving, because you don’t have an electric vehicle to charge. Hence, you have a feeling that solar won’t be worth your time or money to get a system installed.
Our immediate analysis:
Hot water is one of the biggest loads in NZ homes. Currently, this home is using grid power to heat the water. Solar can remove this cost. See our Solar Hot Water page to learn more.
A significant load becoming more popular in residential homes is electric vehicle charging and induction cookers, which require a substantial solar system to provide for. This load is not currently in the home, but could likely be part of this home’s future power demand.
Most of the power usage (apart from the water heating) is during the evening, when the sun isn’t shining.
A North-facing array makes little sense for your particular lifestyle, and you’re more likely to use the output of a West-facing array. Utilising your solar power in your home is more effective at lowering your power bill than injecting the solar power back into the grid.
The large West-facing roof space is perfect for capturing the afternoon sun. A solar system situated on this side can be designed to replace grid power usage in the home during the last half of the sun-day, potential completely removing grid power usage during this time.
A small battery (5 or 6 kWh) could cover your dinner load when the sun goes down. This part of the day for most people is where a big chunk of power is used due to cooking, opening and closing the fridge, water use, dishwasher, lights, etc. This time of the day is also during peak hours of residential power usage, so it tends to be the most expensive time to use power.
So you can see, just providing a brief description of how a home functions can tell solar designers a bucketload of information to tailor the system to suit the user.
Small differences in lifestyles can also play a big influence on how valuable a solar system can be for a home. It’s not one answer to how long the payback period is on a solar system.
Find your WHY.
Get to know your power usage.
That’s the answer.
Solar can be expensive.
When done right, it can be a cheaper way of living.
Photo credit: @frostroomhead | @behy_studio | @norevisions