solar on/off grid installation
I just bought a nice pull behind camper and would like to install some solar panels on it to make it more self contained as well as tie the system into my home when it is just parked. I have tried to...
Forum Discussion
I install both off grid and on grid solar systems for a living. What you want to do is not advisable, not very easy to achieve, and likely will take many many years to recoup the costs involved.
To legally connect a grid interactive solar system in your home you need to sign up for "net metering" with your power company. They will likely will require an AC disconnect switch near your meter that meets their specification. You will also need to have your installation permitted and inspected by the local jurisdiction. You will need to use UL listed equipment that is certified for grid interaction. Many power companies require that a licensed master electrician sign off on the installation on their paperwork.
Are there lots of people who set up illegal grid tie solar systems without doing all of this? Yes. Could they potentially kill a lineman with their system? Yes. Transformers on power poles work both ways. If the line in front of your house is 24,000 volts the transformer steps it down to 240v for your house. If your solar system is feeding 240v into a dead power grid the transformer will turn it into 24,000 volts and send it out on the lines.
In your RV, no you can't connect the charge controller to the AC breaker panel. Charge controllers output is DC and needs to be hooked to a battery bank. You would then connect your battery bank to your AC panel thru an off grid inverter.
If you really want to make the sytem work both ways the best way is to install 2 60 cell panels on your RV. Their Vmp will be around 30 V DC. This will require an MPPT charge controller in the RV. You would also need 2 micro inverters like an M250 from Enphase. You would need a way to have the panels feed the MPPT charge controller when camping and the Enphase inverters while parked. This would require a 4 pole double throw switch arrangement. The output of the micro inverters would need to travel thru a completely separate 240v circuit that would leave your camper, go thru the power company disconnect, and tie into a back-fed breaker in your home's panel.
I find it hard to believe such an arrangement would be very easy to get permitted and inspected but it may be possible.
When all is said and done, if you had 500 watts of solar mounted flat on your camper and tied to the grid every sunny minute of the year you would make about $75 dollars of electricity per year, depending on your power rate.
To legally connect a grid interactive solar system in your home you need to sign up for "net metering" with your power company. They will likely will require an AC disconnect switch near your meter that meets their specification. You will also need to have your installation permitted and inspected by the local jurisdiction. You will need to use UL listed equipment that is certified for grid interaction. Many power companies require that a licensed master electrician sign off on the installation on their paperwork.
Are there lots of people who set up illegal grid tie solar systems without doing all of this? Yes. Could they potentially kill a lineman with their system? Yes. Transformers on power poles work both ways. If the line in front of your house is 24,000 volts the transformer steps it down to 240v for your house. If your solar system is feeding 240v into a dead power grid the transformer will turn it into 24,000 volts and send it out on the lines.
In your RV, no you can't connect the charge controller to the AC breaker panel. Charge controllers output is DC and needs to be hooked to a battery bank. You would then connect your battery bank to your AC panel thru an off grid inverter.
If you really want to make the sytem work both ways the best way is to install 2 60 cell panels on your RV. Their Vmp will be around 30 V DC. This will require an MPPT charge controller in the RV. You would also need 2 micro inverters like an M250 from Enphase. You would need a way to have the panels feed the MPPT charge controller when camping and the Enphase inverters while parked. This would require a 4 pole double throw switch arrangement. The output of the micro inverters would need to travel thru a completely separate 240v circuit that would leave your camper, go thru the power company disconnect, and tie into a back-fed breaker in your home's panel.
I find it hard to believe such an arrangement would be very easy to get permitted and inspected but it may be possible.
When all is said and done, if you had 500 watts of solar mounted flat on your camper and tied to the grid every sunny minute of the year you would make about $75 dollars of electricity per year, depending on your power rate.
