I'm a NOB when it comes to batteries. People are wanting to do plug-in with a battery supplying the inverter like the YT "there's a trick for that" guy. If you have panels delivering to a micro, it's basically pushing to the grid and your house grabs what it can on the way to the utility. But batteries just sit there and service the house hold load, right?

in retirement I have become a DIY solar enthusiast. Kind of a clunky name. How about "heliac", a helios-maniac? I just put up 6 strings, 19 kW, all ground mount, facing different directions and at different tilt angles, sma and ecoflow inverters, 18 kwh battery. I am a heliac.

As far as I know you're not allowed to install solar panels on a roof for an off grid system, but you can put them in your backyard. So long as nothing is hooked up to the grid

fortunately we have a very flat roof that is exposed to the sun all day and I'm wondering if I can put panels up there and weigh them down in a way that they're easily removable

Basically they would go to an inverter and an L1 car charger for a daily commuter

Location is in Bay Area california, suburbs, single family house, the city almost never runs inspections here and removing them off the roof is only a couple of hours worth of work

I can always set them up in the backyard but that's just going to be in the way constantly

Or I can build a carport and put the panels on top.

Additionally I'm planning to put on the roof like three or four panels to do balcony solar? I'm assuming this should be fine, because we don't really have a *balcony to put them on, and I don't really want to hang them out the windows

I understand the appeal of separate components. If the inverter fails, you replace the inverter. If the charge controller fails, the rest of the system may continue working.

But expansion seems to create its own problem. A battery monitor becomes one box. Solar charging becomes another. AC charging adds another device. Then there are DC fuse blocks, disconnects, USB converters, breakers, communication cables, and displays.

The system is technically modular, but it may not be simple, easy to inspect, or easy to move.

For experienced builders: which functions are genuinely better kept separate, and which ones are only separate because that is how DIY products have traditionally been sold? Where would you draw the line between useful modularity and unnecessary complexity?

I’m still fairly new to DIY solar. My original plan was simple: one 12V LiFePO4 battery, a few portable panels, and enough power for lights, a laptop, a small fridge, and charging electronics.

Then the questions started piling up. If I choose a small inverter now, I may regret it when I add a coffee maker or power tool. If I buy a 2,000W inverter, the battery current and cable size become much more serious. Moving to 24V would help, but then some of the equipment I already own becomes less useful.

For people who started small and expanded later: which decision locked you in the most—battery voltage, inverter size, charge controller, or wiring? At what point should a beginner stop “leaving room to grow” and just build for the loads they actually have?

Hi all,

short version: is there a way to tell a victron system to not charge/discharge the batteries while still using the solar energy coming in to offset house consumption?

I tried:

* Setting the JK BMS to "Discharge disabled" (this is technically possible but rather unsexy because I have to do this in every BMS)

* Setting the Multiplus to supply 0W to the house means solar energy is wasted because the energy from the solar only goes to the battery.

* Setting the Minimum State of Charge (SoC) to 100% kicks in a feature in which the Multiplus starts to charge the battery from the grid as the SoC at the moment is more than 5% lower than 100%.

Last year I just switched everything off and started it up in March again. Kind of lame though.

Any better ideas?

Additional info:

I've got a very limited number of solar panels (4 panels with a "balcony" setup with a hoymiles inverter and another 4 connected to victron MPPT and Multiplus). Two years ago I got a little carried away with trying to understand all this stuff and build a couple of batteries (24V, 48V) which resulted in 3 48V MB31 batteries (40something KWh).

In winter, the solar panels do not deliver much (24° degree roof on a shed). The batteries are in the cellar which is not heated. It gets cold - in the range of "do not charge a LiFePo battery" cold). Yes, the batteries do have a heating matt installed and alll settings are in place to heat the batteries. I would like to avoid this thogh. There is simply not enough solar to justify this. And I don't mind wasting some Wh to the grid.

Thx!

Sumry 3600W 120vac 24vdc

Batteries are used K2 24v 9.6ah 245Whr (currently 27 connected, have almost 100, they were like $10 each but only paid for like 60) aluminum bars to connect them. Currently no fuses but each set of 9 will be, but the whole battery is on a breaker. I also plan to clean up cabling when I get a chance. Can fit 9 rows of 9 if I double stack them on one side without worry of them falling off.

10 harbor freight 100W solar panels in series (does about 800W) normal 400W panels are planned, I've just had these for a few years and need extra money to be able to get them.

Can run my fridge and freezer completely on solar and battery when it's sunny. Eventually want to get my server on it, but getting power to the server or Ethernet to the power is what I have to do.

This is all setup in a shed.

I got 10-15k cash to burn and I can't decide on getting interconnected to the power company (ComEd). My goal is to power the critical loads (maybe AC too?).

I'm suffering by paralysis of analysis here and just need to do SOMETHING.

Location: West Suburbs of Chicago IL (ComEd is the power utility company).

ComEd will refund me $300 per kWh so, about $5400 , but I have to be interconnected and they can use them up to two hours a day in the summer. I'll also need a minimum of 2-4 solar panels to qualify for the rebates. These will be ground mounted. Without interconnection, I get no rebates.

Load Shedding / Rate Arbitrage: Can enroll in ComEd Time-of-Day (TOD) pricing. Charge the bank overnight off-peak (~11¢/kWh) and dump power back into the house during the 1:00 PM – 7:00 PM peak window (~32¢/kWh) to offset peak rates. Small amount of panels (4-8) to partially charge the batteries. Ground mounted and connected directly to the battery.

Current Service: 100-amp main panel (Full). 200amp capable at the meter. ( I don't think this has to be upgraded to a 200amp panel)

Usage: Averaging around 875 kWh/month (~28–29 kWh/day), spiking closer to 38 kWh/day in mid-summer with our old AC.

HVAC: Currently swapping out an ancient 80% furnace / SEER 10 AC for a 97% condensing gas furnace (2 speed or variable-speed ECM blower?) and a newer efficient AC.

Roof: Roof is 11 years old. Not looking to mess with roof solar right now—the plan is to wait until the roof needs replacement down the road before doing a full rooftop array.

Battery: Looking at modular LFP options (maybe the EcoFlow DELTA Pro Ultra (x) or Anker SOLIX E10) . 18 KwH? I'm open to off brand, but I'm not the most handy, technical, but not handy.

I think that choosing each brand will require me to go with their smart panels as sub-panels.

Suggestions? Recommendations?

I built this system to provide solar for a remote off-grid location in Micronesia.

It's meant to provide power to a Starlink Mini (40W) and also 75W of USB power over a USB-C and USB-A connector. A Victron display embedded in the front cover of the junction box shows the battery level measured by the shunt. The system runs off two 120Ah 12V AGM batteries, and 3x 100W Renogy flexible panels. The panels and this junction box fit into checked luggage, only the batteries were purchased locally.

Things I would change:

- The Starlink DC converter built-in power switch hanging out the bottom is a hack and I wish I used a different converter and put a proper switch in the side of the junction box.
- The solar input should have been routed through the top of the box instead of the bottom.
- I would have liked a sealed through hole for the Starlink DC barrel instead of dangling power cable.
- I'm not convinced the internal wiring needs to be such a heavy gauge for such short runs.

The MPPT is overpowered so there is the opportunity in the future to upgrade to a 2S2P system with 2x24V batteries instead of 2x12V.

The 2x12V design is meant for robustness. In case one battery fails, the other can still be used alone. Similarly, if the DC-DC converter fails there is a backup USB-C PD supply that can power the Starlink Mini.

An ESP32 (FireBeetle 2 ESP32-E) that forecasts, monitors and controls three existing home power systems as one: an Enphase solar array + battery, a solar-charged hot water tank, and a Hyundai Inster EV charger/V2H (vehicle-to-home) controller. Each system keeps its own independent control and can override the ESP32 at any time. (github code and docs)

The ESP32 downloads forecast solar irradiance from Open-Meteo, adjusts it for local tree/hill shading, and combines it with the 5-day average consumption to forecast today's and tomorrow's Enphase battery state of charge. That forecast drives EV and hot-water charging priority and when (if ever) to discharge the battery back to the grid.

Aim: minimise grid dependence — ideally zero grid draw from 2pm–8pm (when demand charges apply), no exporting surplus solar except a small window 8pm–9pm, and EV charging prioritised over hot water.

The docs include:-

• esp32_control_structure.md — how the BatterySolarMonitor firmware is structured; a function-by-function reference.
• solar_shading_model.md — how the Open-Meteo irradiance forecast is adjusted for this site's tree/hill shading, per sun position.
• solar_shading_stats.md — the back-solved per-angle shade factors behind that model (1200+ days of Enphase production vs. Open-Meteo GTI).
• quarterly_update_process.md — the process (quarterly_update.py) for refreshing the shading model from the latest historical data every 3 months.
• data_sources.md — external APIs the py_programs/ scripts depend on (Enphase IQ Gateway, hot water controller, EV charger).

The code (ESP32 firmware, forecasting/control logic, and the Python shading-model tooling) was written with Claude Code, including the display UI itself.

I'm planning a ground mounted solar array to use with a 5kWh battery for backup power during outages. I'm not trying to go completely off-grid. I mainly want to keep the battery charged during longer outages so I can recharge it multiple times instead of relying on one full charge.

The battery has a built-in MPPT controller that supports up to 3000W of solar input, with an input voltage range of 11–165V. I'm looking at using six 405W panels, but I'm still trying to decide how to wire them.

Option A: 2S3P. Each string would have an open-circuit voltage of around 82V. That leaves plenty of headroom below the 165V limit, even after accounting for colder temperatures. Having three parallel strings should also help reduce the impact of partial shading.

Option B: 3S2P. This would put the open-circuit voltage at roughly 123V. The higher voltage might offer better efficiency in theory, but it also leaves less room below the 165V maximum, especially on cold mornings when panel Voc increases. With only two parallel strings, shading one string would also cut a larger share of the available production.

Has anyone here used 400W or larger panels in a similar 2S3P setup?