I
knew the system would be composed of solar panels and some kind of
inverter to convert the direct current from the panels into
alternating current, but I didn't know much more than that. I had to
learn about all the other widgets that make up a solar electric system
(Translation: I Googled a bunch).
Here
are the major components of the system:
- DC to AC Inverter(s)
- Solar Panels
- PV Racking system
- AC Safety Disconnect Switch
- 20 Amp Double Pole Circuit Breaker
- Enphase Ethernet Gateway (Optional)
- Miscellaneous cabling and conduits to connect the components together
Click here for a bill of materials.
DC to AC Inverter
My idea of a traditional solar electric system consisted of a single, large inverter that converts the power from all the solar panels into household AC current.
As I read, I learned about a different way of doing things. Rather than have a single, large inverter, the idea is to use a small inverter, or micro-inverter, for each and every panel in the system. The advantages include the ability to monitor the power output from each panel, rather than just the whole system, and better power output during partial shading conditions.
From what I've read, the Enphase M215 micro-inverter seems to be the most popular micro-inverter available. Additionally, the manufacturer has excellent documentation, including a long list of approved third party hardware that has been tested with the Enphase product.
Solar Panels
There are two types of solar panels: monocrystalline and polycrystalline. While moncrystalline is the more efficient of the two, this is typically not the deciding parameter. What you want to look for are the power rating, price, and physical size of panel that best fit your application. If choosing an Enphase M215 micro-inverter, then you should also verify the solar panel is on the list of approved panels.
I chose to purchase 270W Suniva Optimus Series solar panels. These panels were about $95 more expensive than the lowest cost 250W panel I could find. When looking strictly at price versus rated wattage, on paper 250W panels seem to be in the sweet spot. A 20 watt difference doesn't sound like much, but this article presents a convincing argument to go with a higher rated panel.
Will paying $95 extra per panel be worth it? I don't know for certain. That's why I'm starting out small. According to the previously mentioned article, a higher rated panel will have better performance under non-ideal lighting conditions, which is most of the time.
PV Racking System
Solar panels need a metal framework to mount to. For that, I found the Ironridge website to be very helpful. They have an online system builder, called the design assistant, that will create a list of all the parts you need for your specific application. The Ironridge racking system is certified compatible with the Enphase micro-inverter.
AC Safety Disconnect Switch
My local utility requires a disconnect switch mounted next to the electric meter. The requirements were rather specific. It could not be the circuit breaker type. Instead, it had to be a knife-blade type with a visibly open gap between the switch contacts. This type of disconnect was surprisingly difficult to find. My local hardware stores did not have this type of switch. After much searching, I chose the Seimens LNF222R 60A non-fused disconnect, and I bought it from Newegg, of all places.
If your utility provider is Ameren, you will also need to attach a sign to the disconnect switch, which meets some rather specific criteria. Refer to the Distributed Generator Checklist for those requirements.
20 Amp Double Pole Circuit Breaker
Because the Enphase micro-inverter is installed directly under each solar panel, the cabling from the circuit breaker panel to the solar panels is no different than traditional home wiring. If you are comfortable wiring a 240VAC circuit in your home, then you can wire this solar system to your home. Keep in mind that all electrical work should be in compliance with local electrical codes.
Enphase Ethernet Gateway
The Enphase Envoy Communications Gateway is an optional device that records the power generated from each Enphase micro-inverter in real-time. Once connected to your local home network, it will upload that data to an Enphase webpage, customized to your specific application. This service is provided free for the lifetime of the product.
For a great example of what this webpage looks like, you can view the Enphase solar system installed at Busch Stadium in St. Louis, MO.
The device itself is simple to install. It does not require any additional wiring to the micro-inverters. It communicates with the Enphase micro-inverters over your home's 120vac power lines. Simply plug the device into a 120vac receptacle, and then plug the device into your home router with the included Ethernet cable.
As cool as this device is, it is not cheap. This module costs $500. I chose to purchase it because I want to log real data over time, confirm my calculations, and then ultimately decide whether or not I want to expand my system. On the other hand, by not purchasing this module, the time to break even financially is reduced by by several years.
Cabling and Conduits
You will need to make a trip to the hardware store and buy the necessary wire and conduits to tie your solar panel system to your circuit breaker panel. In my case, I chose to mount the solar panels to the roof of my shed, which already had a 100 Amp sub-panel in it. I attached the solar panels to the sub-panel via 10/3 with ground inside a length of seal-tight flex conduit. Your application will be different.
DC to AC Inverter
My idea of a traditional solar electric system consisted of a single, large inverter that converts the power from all the solar panels into household AC current.
As I read, I learned about a different way of doing things. Rather than have a single, large inverter, the idea is to use a small inverter, or micro-inverter, for each and every panel in the system. The advantages include the ability to monitor the power output from each panel, rather than just the whole system, and better power output during partial shading conditions.
From what I've read, the Enphase M215 micro-inverter seems to be the most popular micro-inverter available. Additionally, the manufacturer has excellent documentation, including a long list of approved third party hardware that has been tested with the Enphase product.
Solar Panels
There are two types of solar panels: monocrystalline and polycrystalline. While moncrystalline is the more efficient of the two, this is typically not the deciding parameter. What you want to look for are the power rating, price, and physical size of panel that best fit your application. If choosing an Enphase M215 micro-inverter, then you should also verify the solar panel is on the list of approved panels.
I chose to purchase 270W Suniva Optimus Series solar panels. These panels were about $95 more expensive than the lowest cost 250W panel I could find. When looking strictly at price versus rated wattage, on paper 250W panels seem to be in the sweet spot. A 20 watt difference doesn't sound like much, but this article presents a convincing argument to go with a higher rated panel.
Will paying $95 extra per panel be worth it? I don't know for certain. That's why I'm starting out small. According to the previously mentioned article, a higher rated panel will have better performance under non-ideal lighting conditions, which is most of the time.
PV Racking System
Solar panels need a metal framework to mount to. For that, I found the Ironridge website to be very helpful. They have an online system builder, called the design assistant, that will create a list of all the parts you need for your specific application. The Ironridge racking system is certified compatible with the Enphase micro-inverter.
AC Safety Disconnect Switch
My local utility requires a disconnect switch mounted next to the electric meter. The requirements were rather specific. It could not be the circuit breaker type. Instead, it had to be a knife-blade type with a visibly open gap between the switch contacts. This type of disconnect was surprisingly difficult to find. My local hardware stores did not have this type of switch. After much searching, I chose the Seimens LNF222R 60A non-fused disconnect, and I bought it from Newegg, of all places.
If your utility provider is Ameren, you will also need to attach a sign to the disconnect switch, which meets some rather specific criteria. Refer to the Distributed Generator Checklist for those requirements.
20 Amp Double Pole Circuit Breaker
Because the Enphase micro-inverter is installed directly under each solar panel, the cabling from the circuit breaker panel to the solar panels is no different than traditional home wiring. If you are comfortable wiring a 240VAC circuit in your home, then you can wire this solar system to your home. Keep in mind that all electrical work should be in compliance with local electrical codes.
Enphase Ethernet Gateway
The Enphase Envoy Communications Gateway is an optional device that records the power generated from each Enphase micro-inverter in real-time. Once connected to your local home network, it will upload that data to an Enphase webpage, customized to your specific application. This service is provided free for the lifetime of the product.For a great example of what this webpage looks like, you can view the Enphase solar system installed at Busch Stadium in St. Louis, MO.
The device itself is simple to install. It does not require any additional wiring to the micro-inverters. It communicates with the Enphase micro-inverters over your home's 120vac power lines. Simply plug the device into a 120vac receptacle, and then plug the device into your home router with the included Ethernet cable.
As cool as this device is, it is not cheap. This module costs $500. I chose to purchase it because I want to log real data over time, confirm my calculations, and then ultimately decide whether or not I want to expand my system. On the other hand, by not purchasing this module, the time to break even financially is reduced by by several years.
Cabling and Conduits
You will need to make a trip to the hardware store and buy the necessary wire and conduits to tie your solar panel system to your circuit breaker panel. In my case, I chose to mount the solar panels to the roof of my shed, which already had a 100 Amp sub-panel in it. I attached the solar panels to the sub-panel via 10/3 with ground inside a length of seal-tight flex conduit. Your application will be different.