Adding solar panels to an existing system

[Merrill]

I currently have a 6.5kW solar system that puts out 9600 kWh per year and want to add 6 more Sunpower 370 panels. I use around 13,000 kWh per year. Wondering how I figure out if I will not go over 100% of my usage when adding those 6 panels. I assume PG&E will not allow you to generate more solar than you use.

 

[thimel]

PG&E will allow you to produce more than you consume. They just won’t pay you much for it.

 

[jrweiss98020]

The simple math says you need about 8.8 KW to generate 13,000 KWh/year. Your 6 x 370 Watt panels will bring you to ~8.7 KW. Looks like the right number.

You may have to install a larger or second inverter if you aren't using microinverters on each panel...

 

[Merrill]

The simple math says you need about 8.8 KW to generate 13,000 KWh/year. Your 6 x 370 Watt panels will bring you to ~8.7 KW. Looks like the right number.

You may have to install a larger or second inverter if you aren't using microinverters on each panel...

Thanks, I will need to replace my original inverter with a larger wattage unit.

 

[h2ofun]

The simple math says you need about 8.8 KW to generate 13,000 KWh/year. Your 6 x 370 Watt panels will bring you to ~8.7 KW. Looks like the right number.

You may have to install a larger or second inverter if you aren't using microinverters on each panel...

This is why when I put in my solar, I told the folks I wanted the largest inverter I could buy, incase I wanted to put more panels on.
In my case 47 panels, with a solaredge 11400 inverter. During certain peaks in summer, the inverter would hit its limit even though solar could produce more.

If I get approval and put in batteries, I would have 2 gateways. So, I need to buy a second inverter and split up my solar. Just talked to the engr and said even though splitting my solar would say I only needed smaller inverters, I said I still wanted to put in the largest, 11400, since the cost difference is not that much. She said no problemo.

Always need to plan for future changes.

 

[SMAlset]

Also for planning for the future, a consideration is how you place your Powerwalls. While mounting on the wall in your garage or exterior house wall looks nice, it does prevent you from stacking them to accommodate more units if you decide to add more and no longer have the wall space to hang them on.

 

[Akikiki]

This is why when I put in my solar, I told the folks I wanted the largest inverter I could buy, incase I wanted to put more panels on.
In my case 47 panels, with a solaredge 11400 inverter. During certain peaks in summer, the inverter would hit its limit even though solar could produce more.

If I get approval and put in batteries, I would have 2 gateways. So, I need to buy a second inverter and split up my solar. Just talked to the engr and said even though splitting my solar would say I only needed smaller inverters, I said I still wanted to put in the largest, 11400, since the cost difference is not that much. She said no problemo.

Always need to plan for future changes.

In 2019, I upgraded my panels and removed microinverters moving to Solaredge. This year, I am adding more panels and two PWs. With that a second SE inverter. Here, we get state tax credits as well as federal tax credits. While I can, with my new additions, I am considering adding another (third and not yet physcially installed) SE inverter to the system purchase to gain the tax credits and have my own on site backup inverter - just in case - just in case. I hear these stories of lag time in excess of two-three months waiting on a warrantied replacement inverter. When I consider the credits and wait time and what I don't spend in electricity monthly when I am up, it simply seems like its worth the expense at the right time. I see SE inverters on ebay often. I am confident i can sell it later - if I decide to.

 

[h2ofun]

Also for planning for the future, a consideration is how you place your Powerwalls. While mounting on the wall in your garage or exterior house wall looks nice, it does prevent you from stacking them to accommodate more units if you decide to add more and no longer have the wall space to hang them on.

Interesting comment. While talking to the engineer today, the plans show 3 of the batteries stacked. I asked why and she told me it was easier to install that way. I stated I had plenty of room and wanted them all side by side, to not take up more walking space in front of them than I needed. This also would give easier flexibility is someone wanted to add more, stacking would be easy.

 

[h2ofun]

In 2019, I upgraded my panels and removed microinverters moving to Solaredge. This year, I am adding more panels and two PWs. With that a second SE inverter. Here, we get state tax credits as well as federal tax credits. While I can, with my new additions, I am considering adding another (third and not yet physcially installed) SE inverter to the system purchase to gain the tax credits and have my own on site backup inverter - just in case - just in case. I hear these stories of lag time in excess of two-three months waiting on a warrantied replacement inverter. When I consider the credits and wait time and what I don't spend in electricity monthly when I am up, it simply seems like its worth the expense at the right time. I see SE inverters on ebay often. I am confident i can sell it later - if I decide to.

Great point

 

[charlesj]

I currently have a 6.5kW solar system that puts out 9600 kWh per year and want to add 6 more Sunpower 370 panels. I use around 13,000 kWh per year. Wondering how I figure out if I will not go over 100% of my usage when adding those 6 panels. I assume PG&E will not allow you to generate more solar than you use.

When I applied for my solar back in 2012, PG&E would allow 110% of previous year consumption. Plus, the people who prepared the permits for me told them I was planning on adding an electric car or a plug in. Allowed. I replaced all m y lighting over time to LEDs, no electric car or plug in, and depending on weather for the year I am producing 110% to 120% over. So far no issues from PG&E.

By the way, do you have a good place on the roof for the 6 panels?

 

[Merrill]

When I applied for my solar back in 2012, PG&E would allow 110% of previous year consumption. Plus, the people who prepared the permits for me told them I was planning on adding an electric car or a plug in. Allowed. I replaced all m y lighting over time to LEDs, no electric car or plug in, and depending on weather for the year I am producing 110% to 120% over. So far no issues from PG&E.

By the way, do you have a good place on the roof for the 6 panels?

I have 27 panels, 16 are from 2010 and the other from 2016. Originally I thought I could only put them on the flat portion of my roof because my double hip roof had no room on the south or southeast side. Then in 2016 I built a pergola and installed 11 more, at that point I was maxed out. So I have a Hugh tree that comes up thru my back deck that has gotten to big and is becoming a hazard especially when we have the Diablo Winds, my arborists says I need to remove it. So going to do that next spring and then build another pergola and put the additional 6 panels on that, it is also the perfect exposure for solar.

 

[Akikiki]

I have 27 panels, 16 are from 2010 and the other from 2016. Originally I thought I could only put them on the flat portion of my roof because my double hip roof had no room on the south or southeast side. Then in 2016 I built a pergola and installed 11 more, at that point I was maxed out. So I have a Hugh tree that comes up thru my back deck that has gotten to big and is becoming a hazard especially when we have the Diablo Winds, my arborists says I need to remove it. So going to do that next spring and then build another pergola and put the additional 6 panels on that, it is also the perfect exposure for solar.

I too had a space problem. Limited to adding more. So, when I did my update in 2019, I removed panels from 2009 and 2010 and replaced them. Double the wattage performance. Still got the tax credits for new panels and the cost of moving from Enphase to Solaredge. Big big improvement. This allow made sure I had room for the 12 new panels this year to support the PWs. So when this is done, there's not room for even one more panel. Total of 47 for two independent systems tied at the GW.

Anyone adding a Solaredge inverter, I highly encourage you to get (for just a little more) the EV Charging model. Even if you don't need it and can charge - this gives you a backup charging method. Good for testing your existing if it hiccups. And nice to have another for a number of reasons. Makes your home more EV-ready. I'm going to pursue the EV charging EVSE tax credit to help offset the extra expense for the EV charging model (provided my tax guy agrees/supports).

 

[BrettS]

s, I am considering adding another (third and not yet physcially installed) SE inverter to the system purchase to gain the tax credits and have my own on site backup inverter - just in case - just in case

For what it’s worth, I don’t believe that an inverter that is just sitting on the shelf and not in use would qualify for the tax credit. The tax credit applies to an actual functional solar system and not just random solar parts.

 

[Akikiki]

I hear ya. But you are not my tax guy. That's why I said if my tax guy supports it. No offense intended Brent.

 

[SMAlset]

I too had a space problem. Limited to adding more. So, when I did my update in 2019, I removed panels from 2009 and 2010 and replaced them. Double the wattage performance. Still got the tax credits for new panels and the cost of moving from Enphase to Solaredge. Big big improvement. This allow made sure I had room for the 12 new panels this year to support the PWs. So when this is done, there's not room for even one more panel. Total of 47 for two independent systems tied at the GW.

Anyone adding a Solaredge inverter, I highly encourage you to get (for just a little more) the EV Charging model. Even if you don't need it and can charge - this gives you a backup charging method. Good for testing your existing if it hiccups. And nice to have another for a number of reasons. Makes your home more EV-ready. I'm going to pursue the EV charging EVSE tax credit to help offset the extra expense for the EV charging model (provided my tax guy agrees/supports).

Not familiar with a SolarEdge EV charging inverter. Obviously not something available through TE as they sell an EV charging system. We have a NEMA 14-50 outlet and a corded Tesla charger from 2017 we use for both our cars. Does the inverter double as a NEMA 14-50? Won’t be surprised given Tesla always moving to be vertically integrated if they don’t come out with their own inverter in which case I would want to see what that offers. Basically now with our solar and PW system we’re a Tesla household and thinking it would be all tied into the app.

 

[Akikiki]

Not familiar with a SolarEdge EV charging inverter. Obviously not something available through TE as they sell an EV charging system. We have a NEMA 14-50 outlet and a corded Tesla charger from 2017 we use for both our cars. Does the inverter double as a NEMA 14-50? Won’t be surprised given Tesla always moving to be vertically integrated if they don’t come out with their own inverter in which case I would want to see what that offers. Basically now with our solar and PW system we’re a Tesla household and thinking it would be all tied into the app.

Don't misunderstand this. Its part of the SE inverter. Its a box attached permanently to the bottom of the main unit. Here's a picture of mine. And I would not be so quick to presume that TE would not change your BOM to an inverter with EV Charging option. The cable attaches on the black connector that you see on the bottom left corner.

 

[h2ofun]

Don't misunderstand this. Its part of the SE inverter. Its a box attached permanently to the bottom of the main unit. Here's a picture of mine. And I would not be so quick to presume that TE would not change your BOM to an inverter with EV Charging option. The cable attaches on the black connector that you see on the bottom left corner.

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So does the ev charger port only get power from solar and or grid and or batteries?

 

[Akikiki]

So does the ev charger port only get power from solar and or grid and or batteries?

I don't yet have batteries, so I can answer that. But I also charge anytime including night.

 

[nwdiver]

So does the ev charger port only get power from solar and or grid and or batteries?

My understanding of the primary benefit to the Solar Edge EVSE is that it allows the solar and EVSE to share a 40A breaker. This can provide a huge cost savings if the panel is full and the only other option would be upgrading the panel.

 

[h2ofun]

My understanding of the primary benefit to the Solar Edge EVSE is that it allows the solar and EVSE to share a 40A breaker. This can provide a huge cost savings if the panel is full and the only other option would be upgrading the panel.

and maybe more wiring costs?