I have been "kicking around" some ideas on upgrading/expanding my system for a while now. I have a few possible solutions/directions I've thought of, but wanted to run it by folks here to get feedback and/or new ideas. First here is my current system:
2600W of PV panels on two ground mounts, Midnite Solar Classic 150 SCC, Trace (the old one) 4024 inverter, roughly a 30k KWH Lb-C battery bank. This system was originally installed and inspected ~22 years ago and is grid-tied. It was one of the first system the local power company accepted for grid sell back connection then. Some of the components are newer (of course as some of these weren't around 22 years ago) like the battery bank is ~2 years old. It all seems to be working fine, and the Trace has been very reliable over all these years.
My reasons for wanting to upgrade are several fold: First a lot has changed in the time this system was put in, and cost for PVs in particular are a lot lower, meaning I could add capacity fairly cheaply. Lately I am fairly sure my power co is not giving me credit for any/all the power I am sending them; so one thought would be to get a large enough system to mostly meet my power needs and use the power company only when needed; e.g. not sell any excess back. Also, I am considering adding mini-splits (mostly for winter heating) and will need more electric power for these when/if I do.
Upgrade #1 would look something like this: Add a second Trace 4024 inverter with inter-connect cable. This would allow me to produce 240VAC as well as doubling the inverter wattage. It would have to be a used unit, but they seem to be fairly plentiful. It would also allow the continued use of the current (and fairly new 24v batteries), but they might be hard to expand (without giving up some lifespan on the new additions). I would likely also add some additional PV panels on a third ground mount, which would go into a new SCC (as the Classic 150 is at its max with the current panels). I have a line on some local used panels.
This would likely be the least expensive option, and could be done incrementally. Adding a second 4024 and switching the sub panel to be 240v vs 120v is fairly simple and straight forward. A second string/set of PVs and SCC can be added as another enhancement. So it would have cost and ease of change over to its advantage.
The disadvantages are: the current battery bank is likely not really large enough for the full expansion (especially if excess power is not going back to the grid) and would not be easy to enlarge. Even with a second 4024, the 8KW total power output is probably not quite large enough to handle the whole house's loads (although close right now as there are few high wattage appliances currently, at least before the mini-splits are added). It would leave me with 20+ year old technology and monitoring, whether an advantage or disadvantage I leave to the reader
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Upgrade #2 might look something like this: Replace the Trace 4024 with a modern inverter with a capacity to handle the whole house loads now and with possible mini-splits. Probably a unit which includes SSCs. Most likely replace the batteries or at least increase their numbers so they are at 48v, as most modern inverters are 48v. Again likely will add more PVs on a third ground mount.
Advantages are: Increased total power, maybe 12-15KW, with the potential to run the entire house including mini-split additions. Much better monitoring and control would come with a modern inverter. Size-wise a modern 240VAC inverter is much smaller than two 4024's (and lighter too at least the hi freqency ones). Likely will come with integrated SCC's and CB's.
Disadvantages: likely 2 to 3x the cost of option #1, perhaps more if I also switch over to Li batteries too. It would be hard to do this change incrementally; with the possible exception of adding more PV's. It would be a major change/re-work of the current system wiring and the house wiring panels.
As I see this, these two upgrades more or less roughly define the possibilities. I'd be interested in hearing what folks here think, other advantages/disadvantages or entirely different directions. Let me know what you think.
2600W of PV panels on two ground mounts, Midnite Solar Classic 150 SCC, Trace (the old one) 4024 inverter, roughly a 30k KWH Lb-C battery bank. This system was originally installed and inspected ~22 years ago and is grid-tied. It was one of the first system the local power company accepted for grid sell back connection then. Some of the components are newer (of course as some of these weren't around 22 years ago) like the battery bank is ~2 years old. It all seems to be working fine, and the Trace has been very reliable over all these years.
My reasons for wanting to upgrade are several fold: First a lot has changed in the time this system was put in, and cost for PVs in particular are a lot lower, meaning I could add capacity fairly cheaply. Lately I am fairly sure my power co is not giving me credit for any/all the power I am sending them; so one thought would be to get a large enough system to mostly meet my power needs and use the power company only when needed; e.g. not sell any excess back. Also, I am considering adding mini-splits (mostly for winter heating) and will need more electric power for these when/if I do.
Upgrade #1 would look something like this: Add a second Trace 4024 inverter with inter-connect cable. This would allow me to produce 240VAC as well as doubling the inverter wattage. It would have to be a used unit, but they seem to be fairly plentiful. It would also allow the continued use of the current (and fairly new 24v batteries), but they might be hard to expand (without giving up some lifespan on the new additions). I would likely also add some additional PV panels on a third ground mount, which would go into a new SCC (as the Classic 150 is at its max with the current panels). I have a line on some local used panels.
This would likely be the least expensive option, and could be done incrementally. Adding a second 4024 and switching the sub panel to be 240v vs 120v is fairly simple and straight forward. A second string/set of PVs and SCC can be added as another enhancement. So it would have cost and ease of change over to its advantage.
The disadvantages are: the current battery bank is likely not really large enough for the full expansion (especially if excess power is not going back to the grid) and would not be easy to enlarge. Even with a second 4024, the 8KW total power output is probably not quite large enough to handle the whole house's loads (although close right now as there are few high wattage appliances currently, at least before the mini-splits are added). It would leave me with 20+ year old technology and monitoring, whether an advantage or disadvantage I leave to the reader
...Upgrade #2 might look something like this: Replace the Trace 4024 with a modern inverter with a capacity to handle the whole house loads now and with possible mini-splits. Probably a unit which includes SSCs. Most likely replace the batteries or at least increase their numbers so they are at 48v, as most modern inverters are 48v. Again likely will add more PVs on a third ground mount.
Advantages are: Increased total power, maybe 12-15KW, with the potential to run the entire house including mini-split additions. Much better monitoring and control would come with a modern inverter. Size-wise a modern 240VAC inverter is much smaller than two 4024's (and lighter too at least the hi freqency ones). Likely will come with integrated SCC's and CB's.
Disadvantages: likely 2 to 3x the cost of option #1, perhaps more if I also switch over to Li batteries too. It would be hard to do this change incrementally; with the possible exception of adding more PV's. It would be a major change/re-work of the current system wiring and the house wiring panels.
As I see this, these two upgrades more or less roughly define the possibilities. I'd be interested in hearing what folks here think, other advantages/disadvantages or entirely different directions. Let me know what you think.
