There are a few considerations to take into account when properly sizing a solar system. Our calculator here, is fairly conservative but there are many different factors to take into account when sizing. The more accurate you are in sizing the better the return on your investment will be. I hear many naysayers spout off much to do about how solar will never be worth the price. I find it interesting usually those people are the very ones who want you to keep buying power from power companies or go on old theories of solar power i.e. batteries, 100 percent coverage of your power usage, or disconnecting from the grid, etc.

General rule is if you are already connected to the grid, STAY CONNECTED. Do not think you should disconnect from the grid just to use solar. For the next 100 years at least we as a society will always need grid power in some form or fashion. Very similar to needing music but using cd’s, dvd’s, and now mp3s, rather than albums. The format we listen to music on changes and gets better over time. So will grid power and solar power and energy management techniques.

In light of this being able to change your solar system over time, will provide value to your system. Choosing systems that are upgradeable, extendable, can add batteries, more solar panels etc. will provide you a long term excellent solar system. Upgradeability also allows you to start smaller and spend less up front then get to know how your solar works and over time as the need changes or the landscape for solar changes (tariffs, pricing, and technology) you can adapt rather than needing to scrap one system just to buy another.

It is also not necessary to use pitching legs in order to get the perfect degrees and forgo the cost of the legs in your equation.  Quite often and in fact almost always it is better to reduce the upfront costs and go flat against the current roof pitch rather than pitch them perfectly.  It also looks better, has better wind resistance, and provides for a cooler roof attic under the panels,  gets less objection from your neighbors (if you care about this, lol), and cost less which improves your payback. 

Also the sun rises in the East and sets in the West.  Most people use more power on average in the afternoons than in the mornings.  So facing panels perfectly north is also not necessary  and in most instances your roof will have some sort of face in the direction of NE to NW and using the existing face direction is cost effective, and eliminates pitching the panels.  So our advice is to roll with the existing pitch and face orientation and simply let the panels do the collecting and if necessary simply add a panel if need be for more collection, it is a cheaper, better looking option, and better in the wind long term. 


Single Phase- In most circumstances a single phase property will be limited to 5kw of solar power.

2 phase power-  Some places in New Zealand use this methodology and Micro inverters really come into their own in this situation as the older string inverters do not do 2 phase, meaning you will need to install 2 single phase inverters to cover your power on a 2 phase house, either that or only cover one phase with solar (which technically unbalances the system and not advised). 

3 phase power-  Can use a three phase string inverter (cheaper) or Micro inverters.  Micro inverters give you the ability to cover loads better and eliminate feeding back to grid better.  Older string inverters split the phases into 1/3,1/3, 1/3 so if one phase is loaded less than the others (supposed to be balanced by electricians but not always) it will feed back to the grid your generated power split on that 1/3 (meaning you cant manipulate the 1/3 going to that phase) 

For the most part when you apply to the lines company in your area to grant permission for your solar system to be connected to the grid you will need to fill out the form with the type of equipment, size of system, and phases, and the name of the electrician who will connect it to the distribution board.  Most solar companies who do everything for you fill this form out for you but need your signature and understanding of what your signing which most people don’t understand.  So buy getting the equipment yourself, sizing it right, and choosing the type of equipment you gain understanding which will actually let you fill the form out for yourself and more importantly understand it before signing it. Line companies are not your electric retailer.  The lines company is the owner operator of the lines themselves which then sell to the retailer who sells onto you.   You can find out who this is by simply researching your area on the internet and then download the form and read it.  It is simple and could save you thousands on your solar system.  When you get the equipment you can then contact your local electricians, and others to install and isolate the installation quotes to compare who to get to do it.  If you are comfortable or capable to install yourself you can, and then simply get your local electrician to connect it to your distribution board.  This of course is some generalities, and by no means are we suggesting you go up on your roof if you never been up there or do not know how to use a wrench, or hand drill or can not lift 25kgs,  and NEVER ever try to connect the cable yourself unless you are a registered electrician.  If you do this you will void any insurance on your home and will need a certificate of compliance for the connection to supply to the lines company for final approval.  If you do not get this you could be disconnected from the grin by the lines company. Do not mess around here as electricity is serious.   Noting prevents you from getting the equipment of your choice here at Solar Direct and then contracting labour to help install.  You will still save money rather than have someone sell you a package of equipment and installation. 

In most circumstances you should remove your economy meter (hot water meter)  and place your hot water cylinder on your main meter that has your solar system on it.  You do not need any fancy diverters to send the energy to the hot water system and supposedly eliminate feeding back to the grid.  These cost on average over $700 and when the hot water system turns on it pulls from the solar anyways, and when its to temperature automatically feeds back to the grid on either system, so buying this piece of equipment is unnecessary in our option and cost more than it saves hurting your return on investment of the system.