Skip to content

Home Solar Project - Next Steps

Continuation of the home solar project.

Current State

As of the creation of this post, my system is technically "complete", and there are no additional items planned for changes/removal via my installer.

Adding more insulation

As apart of the contract with my solar-installer, the insulation in my attic was brought up to 20 inches.

To give an idea, areas of my attic barely had 2-3 inches.

Here are a few before/after shots. In the before shots.

Facing East

Facing West

I imagine the impact from this will be extremely noticable, especially once it starts warming up outside. During the summer of last year- we experienced average termps of 100-110F every single day, for nearly two months.

My A/C was running constantly, leading to over 3Mwh of consumption, per month.

For reference, here is my electrical usage for the last two years.

3.5Mwh = 3,500Kwh * 0.08c/Kwh = 280$ worth of electricity.

Future Projects

Adding more battery

The net-metering agreement with my utility provider, is not the best.

When I consume energy from the grid, it costs me 0.08c/kwh.

When I push excess energy back to the grid, I receive 0.03c/kwh.

So, it is in my best interest to be able to store all of my production into battery, and release when needed.

To visualize this trend- here is daily stats coming from solar-assistant.

Daily Stats from Solar-Assistant

As you can see, during the heating season, I pretty consistently consume around 30Kwh of energy per day.

The issue in the metrics here- See the grid exported column. If we are pulling energy from the grid, AND, exporting energy to the grid- we don't have enough battery storage.

To better demonstrate this, here is a graph I setup in Grafana, showing yesterday's data.

Grafana Energy Dashboard

The gred area, is grid usage. Notice- during the early morning hours, my battery is essentially empty (I have a 40% reserve set), and most of my energy is pulled from the grid.

When the sun comes out (yellow area), by around noon-1pm, my batteries are fully charged, at which point I start dumping excess production to the grid. (Red area below the center)

Well, when the sun starts going down, battery usage ramps up. The problem is- After 4-6 hours, the battery is hitting my reserve limit of 40%, at which point, battery consumption tapers off, and grid usage climbs.

From 10pm to 8am, the bulk of my power comes from the grid.

Since- I know my daily off-season energy consumption is 30-34kwh, My plan is to scale my DC system up to 30kwh of total capcity. This should be enough to allow me to store/release my energy all night.

(Also- to scale beyond 30kwh, I would need to add an additional battery rack.)

So- in the next month or two, look forward to seeing the addition of 4 new 48v 5kwh batteries.

Estimating ROI / Savings

As the year goes on, I will be estimating the savings / ROI of this solution. However, it will take a full year before I can get an accurate anwser as to, "Was this worth it".

I think the summer will tell a very interesting picture- especially when I am able to produce a lot more energy, for a longer duration.

And- since, lots of sun generally means, lots of heat, I think this should offset a large chunk of the HVAC consumption.

But- only time will tell. Stay tuned.