When you are thinking to go solar for a brand new construction, one of the main questions that needs to be answered is whether you want to be off-grid or connected to the grid. For starters, check with the local laws to see if you are allowed to stay off-grid. Many do not allow it even though solar systems themselves are encouraged. Some might allow you to stay off-grid provided you have some kind of backup power to fall back on – this is normally a gas powered generator.

The second question that needs answering for any solar installation is the capacity of the system. I have explained how you can estimate this from your electricity bill in the video below.  Or you can use one of the numerous calculators that are available online. Try this solar calculator from gogreensolar.

Once you know how big your system needs to be, decide if you would like to do the work yourself or if you want to ask a company like gogreensolar to do it for you. Companies can generally quote you labor rates that are a function of the system wattage (capacity). If you choose to do it yourself, remember that roof mounting is more complicated than a ground mount. Ground mounts also come with mounts that track the sun in order to maximize the efficiency of the system.

A solar system only has a few major components :

  1. The solar panels which generate electrical power in DC (direct current)
  2. The inverter which converts this DC to AC since most equipment we use operates on AC
  3. Batteries to store any excess power generated during daytime for use during the night
  4. An optional; but recommended charge controller to prevent the batteries from being overcharged.
  5. Mounting hardware (either roof or ground static or ground tracking)
  6. Odds and ends -> connecting cables, wires, fuses and relays

You could choose to buy these items piecemeal if you know what you are doing. Or  you can buy one of numerous kits available. Kits normally come with software that can monitor the system. They typically do not include items 4 and 6. The parts in item 6 can be easily purchased in hardware stores for a few hundred dollars. The system is basically the same whether you are off-grid or connected to it with the exception of item 2. You have to use a grid-tie-inverter if you connect to the grid and a sinewave or modified sinewave inverter if you are off-grid.

Many solar kit suppliers only keep grid-tie inverters. For e.g., take a look at this kit from gogreensolar.

If you want to stay off-grid, you will have to obtain the inverters from a company that supports those inverters like BackwoodsSolar. BTW, I think their site is very informative and a must read if you are trying to do this on your own.

Another informative site is freesunpower.

It is best to keep a backup generator handy if you plan on staying off-grid.  You could even wire it up intelligently, wherein a relay system ensures that on the failure of the solar system, the generator only powers a few critical items and a couple of power outlets.

If you do plan to connect to the grid, once you have installed your solar system with a grid-tie inverter; the power company will come and install a box that does net metering. It basically monitors how much power your system is generating and how much it is drawing from and feeding into the grid. For the most part, you get to purchase electricity at wholesale rates; while you sell any excess to the grid at retail rates. The justification is that the distribution losses/costs are lesser with private distributed solar generation compared to a wholesale generator who has to transmit power over long distances. You will be surprised to know that energy transmission losses are as high as 50% for a conventional grid. However don’t bank on this favorable pricing scheme to cover your initial capital investment on your solar system, since these terms could change overnight. Also, note that power suppliers do not want you becoming a mini generating station. The largest capacity of your solar system can only be twice your average consumption. You could go higher; but there are loops to jump, papers to file and insurances to be taken.

This link is for the dual port solar charger that we use to charge small electronics over USB ports – e.g., smart phones, camping lantern, camcorder and battery packs. It has worked extremely well for us. Just to put things in perspective- this unit is an extremely low power, off the grid solar system that can only power devices running off DC. Also, since it lacks storage batteries, it can only charge items when there is solar power available.

We will go into the detailed system design sometime next year. But for now we need to understand some aspects of the system for plannning.

  • If we are using a roof mount system, it would play into the roof design.
  • In our case, since we are placing it on the ground, we want to ensure that we pick and set aside a sunny spot on the land for the solar panels.
  • A rough pricing of the system helps with the overall budgeting for the project. Also, prices of solar panels and batteries can be expected to down over the next few years. So we might put a very small battery for our new system and upgrade the battery packs when Elon Musk comes out with a better battery!!
  • If the county rules require you to connect to the grid, you might not have any money left to spend on solar panels – trust me on this one because the cost to get new power connections to the grid for raw land can be surprisingly high.

#electric #design