Worth upgrading older solar system?

[rpatel18]

My inlaws recently moved into our old house we own in Bakersfield, CA and we were wondering if it would be worth the money to upgrade the solar and put a battery system in. We purchased the house in 2018 and the previous owner had a solar system installed around 2014.

I'm not sure what the panel specs are but there are 20 of them on the roof and there seems to be some discoloration where some of the black parts of the panels are looking slightly brownish (forgot to take a picture of it when I was on the roof). On the inverter, it says Sunny Boy SMA Technologies AG. There is a screen on the inverter showing the stats and I've seen it at most output ~3kw and it says its output a total of 101,643kwh so far.

We're on a E1 WB Residential Service rate, and I'm not exactly sure what they will pay in true up but I remember that when we were here, we paid about ~$1.8k in true up costs per year which I thought was quite a bit for having a solar system. The other change that we're going to make is to install a heat pump this fall, the AC unit is fairly old and is on its last leg. My assumption is that they are on NEM2 or maybe even NEM1? But I also don't know if upgrade solar or adding a heat pump changes what rate tier we're on and changes the math.

How do I start to figure out if upgrading the current solar is worth it and if so, how much is worth spending then?

 

[MisterSandals]

How do I start to figure out if upgrading the current solar is worth it

Can you get a pic of the label on back of one of the panels? Extra credit if you can figure out how they are wired together.

we paid about ~$1.8k in true up costs per year

How many kWh do you use in a year?

 

[rpatel18]

Didn't see any labels under the panels. Did get up to the roof and snapped some more pictures.

 

[MisterSandals]

Didn't see any labels under the panels. Did get up to the roof and snapped some more pictures.

Put your phone under the panel and snap a few (timer function might help). Should be in the center, perhaps 2/3 to 3/4 of the way towards where the wires exit the panel.

Its there.

 

[Kuma]

Call your utility company, dont know if youre on PGE, and they can provide information on what NEM you are on and what NEM you will be possibly moved to if solar is upgraded. They can also provide your historical usage. PGE has all this info online. Also, PGE has some grey area and allows up to 1k watt increase for existing solar systems.

 

[rpatel18]

on the energy usage.. hard to say as we don't have an energy monitor but we've gotten billed an average of 602kwh/month since 2018. Here is the chart of our billed kwh since 2018 as well.

 

[400bird]

You'll need more real data to perform any actual cost comparison.

You're very limited to how much solar (1kw) you can add to the system before you'll get kicked up to the current plan NEM3/successor tariff.
There's a drastic difference in the "net" portion of the agreement, meaning the new agreement is not net at all.

If you are looking to pay PGE less than the current true up, you'll probably need to add a battery to shift your solar energy and power the house loads overnight.

And yes, adding a heat pump will likely increase energy usage as there's about a 99% chance that your heat, in California at least, is natural gas uses just a little energy to run the fan. Moving to a heat pump will increase energy usage. This increased heater energy usage might be offset by the increased AC efficiency, but again, you'd need real numbers, these would be more difficult to gather than the panel labels.


I think the next step in this process is to get the last year of energy usage data from PGE

 

[400bird]

on the energy usage.. hard to say as we don't have an energy monitor but we've gotten billed an average of 602kwh/month since 2018. Here is the chart of our billed kwh since 2018 as well.

Good enough to start with!
You can play around in PV watts to get an idea what you'd need to offset current energy usage:

PVWatts

Estimates the energy production and cost of energy of grid-connected photovoltaic (PV) energy systems throughout the world. It allows homeowners, small building owners, installers and manufacturers to easily develop estimates of the performance of potential PV installations

pvwatts.nrel.gov

Per my random guess in PV watts, something like an additional 4kw of panels would get you close to 0, add in some additional PV to cover the heat pump, maybe 6kw of solar + inverter + battery.