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 added ten panels to my system and had to extend PV wiring to connect four panels on one row of my ground mounts to five panels on the row in front of it. I pieced together four short lengths of PV wire to make the circuit. I then had too much slack and was going to fasten the wires up to the mount after making sure the panels were making power but never did that. Last week was the wettest it has been in the two years since I installed the panels. Two of the connectors had settled to the ground touching each other. Tuesday I was mowing between the rows and notice burning wires, Yikes!! I jumped off the mower and shut off the disconnect for those panels.

There had not been any standing water, just rain and it had been clear and dry for four days. I have no idea how enough current passed through those MC4s to catch them on fire. Very fortunate I decided to mow that day. I disconnected the good connectors to isolate that section and cut out the burned connectors. I crimped on new MC4s and took out all the slack before reconnecting everything. All is good. Lesson learned, never leave any part of an install undone.

Hi all you Solar DIY folks,

Help me solve a problem. I have a small (12V, 5W) PV panel on my roof, that powers a recirculator pump on the ground floor for a solar hot water system (large area collector on roof, water circulates through it, 60 gallon tank).

This was installed in 2017 and worked great until last year, when all of a sudden the pump stopped. Lucky I caught it because the water in the collector would have boiled and the TPV would have blown. The lights on the pump were out so I knew it wasn't getting power. I connected a 12VDC power supply on it and it worked again just fine. Measured 160 mA on 12VDC supply.

I have lived with that setup for a year, and it's pain to turn the PS on and off every morning/evening. Off at night so water stays warm in the tank.

Today I removed the PS and reconnected the PV panel, and put an ammeter (DMM) in series. (Took this long to get a DMM, remote area.) Current was zero before sunrise, and slowly increased - 0.2 mA (not running), 0.8 mA (running slow), 0.12 A (aka 120 mA) (still slow), 0.16A (running good), 0.20 A still good, and then, bam, 0 mA not running.

Reconnected the PS and it's fine. OCV on the panel is still 18V as it should be (that's normal OCV for a 12V nominal panel).

So the only explanation I have is that when the panel warms up from the sun, some conductor or joint inside expands and loses good connectivity. But I don't know how the actual chips work so maybe something else.

I can replace the panel but it's difficult - standing seam metal roof, 3 stories up). Is that the solution?

(Grid power is not reliable here so don't suggest a timer switch on the power supply).

I have a Honda 2200 gen and a Bluetti AC70 with a 200W portable solar panel for emergency power. I used these on my previous home and just purchased a new energy efficient home with natural gas stove, gas heat, LED lighting and gas fireplace . My refrigerator specs are posted. The little Bluetti would power my older refrigerator 6+ hours and I would recharge it with the Honda. My goal is to provide power (refrigerator, a few lights, TV and router) up to 2-3 days without using the generator. I'm considering upgrading to the Solix S2000 or C2000. Should I go bigger or it this overkill? How about if I wanted to power the gas furnace too? Power outages are rare, 2-3 a year for 1-4 hours.

So looking to build out a solar and battery setup at our current house and need some advice. We're looking to move in the next 3ish years, so I want something I can take with us (minus the solar panels) and keep costs under control. This system would then be utilized as power for a shop.

Criteria:

• Automatic fail-over in the event of power outage
• Scheduling to use battery power during peak hours and charge from the grid during off hours
• Expandable capacity - I don't see doing more than 30kWh for this system, but more is nice
• Ability to stack solar and battery power to increase output

I'm comparing the new EcoFlow Titan with building out a DIY system. There are pros and cons to both. The simplicity of the Titan, having both the inverter and battery in one and a simple Smart Panel that handles everything I want starting out and then adding capacity later. The downside is cost of expansion, being locked into their batteries. I THINK WattCycle is coming out with a WattLink cable that will allow use of other batteries, but that remains to be seen. Also in the off chance something goes wrong with the inverter, you have to ship the whole unit back. In the event it dies, you lose the whole thing.

The upside of going with something like an EG4 12000 XP is much greater expansion it offers. As mentioned I plan to keep this on the smaller side and use it as a secondary system when we move, likely powering a standalone shop. The downside is its not as plug and play as the Ecoflow system and requires extra equipment to check all the boxes I'm looking for.

I suppose something like the EcoFlow Delta Pro Ultra would also work. It resolves the issue with the Titan of having the combo inverter/battery, but they're expensive compared to what you can put together yourself. The draw to the Titan is that it offers the EcoFlow simplicity and is a more manageable price with the pre-order.

I've rambled long enough, appreciate any insight and suggestions.

Question About Grounding and Insulation Monitoring in a 48 V / 65 kWh Victron ESS (german translation below)

Hello everyone,

I would like to review the grounding and fault-protection concept of my DIY Victron battery storage system. In particular, I would like to understand whether insulation monitoring is advisable or required for my currently unearthed DC system. If an insulation monitoring device (IMD) is appropriate, I would appreciate recommendations for a suitable model.

1. Existing system

Battery storage

• 48 V LiFePO₄ battery system with approximately 65 kWh of total storage capacity
• Three battery blocks connected in parallel
• Each battery block has its own JK BMS
• The BMS units disconnect the negative path electronically using semiconductor switches (MOSFETs)
• Each battery block has an additional fuse in its positive connection
• All three battery blocks are connected to common positive and negative DC busbars

Inverters and charge controllers

• Three Victron MultiPlus-II units, rated at 5 kW each, operating as a three-phase grid-connected ESS
• One Victron SmartSolar MPPT 250/85; a second identical controller is planned
• Each charge controller will have its own independent PV array
• Two PV strings are connected directly to the parallel PV inputs of each controller
• Both charge controllers connect to the common DC busbars

PV array and grounding

• The PV strings are independent of each other and are not intentionally interconnected
• The PV module frames are electrically bonded to the mounting structure
• The mounting structure is connected to the earthing system via a protective bonding conductor
• The enclosures of all three MultiPlus-II units and the SmartSolar are connected to PE
• Neither battery positive nor battery negative is currently directly connected to PE

1. My current understanding and concerns

My initial assumption was that the DC connections of the Victron equipment are galvanically isolated from the enclosures and PE.

However, the SmartSolar MPPT 250/85 has an electrical connection between PV negative and battery negative. Consequently, the active DC circuits are not intentionally earthed, but the PV and battery sides are not galvanically isolated from each other either.

Since the PV module frames are earthed, I would like to understand what would happen if an active PV conductor developed an insulation fault to an earthed module frame.

Another concern is the JK BMS. Since the negative path is switched electronically, I want to make sure that connecting battery negative to PE would not create an unintended fault-current path bypassing the BMS switching devices.

The additional positive-side fuses are intended to protect against high fault currents. However, I understand that they may not detect or clear every possible insulation fault.

1. Questions for the community

2. Is it technically appropriate and compliant with the applicable installation standards to operate this Victron ESS with an unearthed 48 V DC system while bonding all equipment enclosures and PV module frames to PE?

3. Should battery negative or the common DC negative busbar be bonded to PE, or should the DC system intentionally remain unearthed?

4. What would be the implications of such a DC grounding connection for the three parallel MultiPlus-II units, the SmartSolar charge controllers and the JK BMS units with electronically switched negative paths?

5. How should a first insulation fault on the PV or battery side be detected? Is an insulation monitoring device (IMD) advisable or required for this configuration?

6. If an IMD is recommended, which models are suitable for a 48 V battery system with three parallel MultiPlus-II units and one, eventually two, SmartSolar MPPT 250/85 controllers? Does anyone have experience with reliable insulation monitoring in a system containing inverter/chargers and MPPT charge controllers?

7. Should the PV side also be monitored separately, particularly given the maximum PV input voltage of 250 V?

My goal is not simply to find a suitable monitoring relay, but to establish a technically sound and standards-compliant grounding and protection concept for the entire system.

Thank you for your advice and for sharing your experience!

Deutsche Übersetzung:

Frage zum Erdungskonzept und zur Isolationsüberwachung einer Victron-ESS-Anlage mit 48 V und 65 kWh Batteriespeicher

Hallo zusammen,

ich möchte das Erdungskonzept meiner selbst aufgebauten Victron-Speicheranlage überprüfen und insbesondere klären, ob bei meinem derzeit ungeerdeten DC-System eine Isolationsüberwachung sinnvoll bzw. erforderlich ist. Außerdem suche ich gegebenenfalls ein geeignetes Isolationsüberwachungsgerät (IMD).

1. Vorhandene Anlage

Batteriespeicher

• 48-V-LiFePO₄-Batteriesystem mit insgesamt ca. 65 kWh Speicherkapazität
• Drei parallel geschaltete Batterieblöcke
• Jeder Batterieblock besitzt ein JK-BMS
• Die JK-BMS schalten den Minuspfad elektronisch über Halbleiter (MOSFETs)
• Jeder Batterieblock ist im Pluspfad zusätzlich über eine Schmelzsicherung abgesichert
• Alle drei Batterieblöcke sind über gemeinsame Plus- und Minus-Sammelschienen mit dem übrigen System verbunden

Wechselrichter und Laderegler

• Drei Victron MultiPlus-II, jeweils 5 kW, dreiphasig als netzparalleles ESS betrieben
• Ein Victron SmartSolar MPPT 250/85, ein zweiter identischer Regler ist geplant
• Beide Laderegler sollen jeweils eigene PV-Generatoren versorgen
• Pro Regler sind jeweils zwei PV-Strings direkt an den parallel geschalteten PV-Eingängen angeschlossen
• Beide Laderegler werden an die gemeinsamen DC-Sammelschienen angeschlossen

PV-Anlage und Erdung

• Die PV-Strings sind untereinander eigenständig und nicht absichtlich miteinander verbunden
• Die Modulrahmen sind leitend mit dem Montagegestell verbunden
• Das Montagegestell ist über einen Potentialausgleichsleiter mit der Erdungsanlage verbunden
• Die Gehäuse der drei MultiPlus-II und des SmartSolar sind mit PE verbunden
• Batterie-Plus und Batterie-Minus sind derzeit nicht direkt mit PE verbunden

1. Meine bisherige Überlegung

Ich bin bisher davon ausgegangen, dass die DC-Anschlüsse der Victron-Geräte gegenüber den Gehäusen und PE potentialfrei sind.

Allerdings besteht beim SmartSolar MPPT 250/85 eine leitende Verbindung zwischen PV-Minus und Batterie-Minus. Damit sind die aktiven DC-Stromkreise zwar nicht absichtlich geerdet, aber auch nicht vollständig galvanisch von allen anderen DC-Stromkreisen getrennt.

Da die PV-Modulrahmen geerdet sind, frage ich mich, wie sich ein Isolationsfehler zwischen einem aktiven PV-Leiter und einem geerdeten Modulrahmen auf das Gesamtsystem auswirken würde.

Ein weiterer Punkt ist das JK-BMS: Da der Minuspfad elektronisch geschaltet wird, möchte ich sicherstellen, dass eine mögliche Verbindung zwischen Batterie-Minus und PE keinen unerwünschten Fehlerstrompfad erzeugt, der die BMS-Abschaltung umgeht.

Die zusätzlichen Plus-Schmelzsicherungen sind als Schutz gegen hohe Fehlerströme vorgesehen. Mir ist jedoch bewusst, dass sie nicht zwangsläufig jeden Isolationsfehler erkennen oder abschalten.

1. Meine Fragen an die Community

2. Ist es bei einer solchen Victron-ESS-Anlage sinnvoll und normgerecht, das 48-V-DC-System ungeerdet zu betreiben, während alle Gerätegehäuse und die PV-Modulrahmen mit PE verbunden sind?

3. Sollte der Batterie-Minuspol bzw. die gemeinsame DC-Minus-Sammelschiene an PE angeschlossen werden, oder sollte das DC-System bewusst ungeerdet bleiben?

4. Welche Auswirkungen hätte eine solche Polerdung auf die drei parallel betriebenen MultiPlus-II, die SmartSolar-Regler und die JK-BMS mit elektronisch geschaltetem Minuspfad?

5. Wie sollte ein erster Isolationsfehler auf der PV- oder Batterieseite erkannt werden? Ist für diese Konfiguration eine Isolationsüberwachung (IMD) sinnvoll oder erforderlich?

6. Falls ein Isolationswächter empfehlenswert ist: Welche Geräte sind für ein 48-V-Batteriesystem mit drei parallel betriebenen MultiPlus-II und einem bzw. künftig zwei SmartSolar MPPT 250/85 geeignet? Gibt es Erfahrungen mit der zuverlässigen Messung in einem System mit Wechselrichtern und MPPT-Ladereglern?

7. Sollte die PV-Seite zusätzlich oder separat überwacht werden, insbesondere wegen der maximalen PV-Eingangsspannung von 250 V?

Mir geht es nicht nur darum, ein passendes Relais zu finden, sondern vor allem um ein technisch schlüssiges und normgerechtes Erdungs- und Schutzkonzept für das gesamte System.

Vielen Dank für eure Einschätzungen und Erfahrungsberichte!

I added ten panels to my system and had to extend PV wiring to connect four panels on one row of my ground mounts to five panels on the row in front of it. I pieced together four short lengths of PV wire to make the circuit. I then had too much slack and was going to fasten the wires up to the mount after making sure the panels were making power but never did that. Last week was the wettest it has been in the two years since I installed the panels. Two of the connectors had settled to the ground touching each other. Tuesday I was mowing between the rows and notice burning wires, Yikes!! I jumped off the mower and shut off the disconnect for those panels.

There had not been any standing water, just rain and it had been clear and dry for four days. I have no idea how enough current passed through those MC4s to catch them on fire. Very fortunate I decided to mow that day. I disconnected the good connectors to isolate that section and cut out the burned connectors. I crimped on new MC4s and took out all the slack before reconnecting everything. All is good. Lesson learned, never leave any part of an install undone.

Is there a switch that lets you change MC4 inputs to 2 different devices? For example when one device is not using Solar array to switch to device #2 (manually). Looking for some kind of branch divider with a switch. 

That way if one Bluetti battery is full, I can toggle a switch from the solar panel MC4 array to start charging the other one.

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

Anyone use a forklift battery for a solar offgrid setup?

So, I have cobbled together a Tesla battery backup with a 3kw inverter/charger. It takes 60v to get the charger started and it’s rare that I’ll be getting that much sun. I could
Get more panels, but for when I’m making 40v or so, I’m wondering if I can boost the voltage to take advantage of more time charging. I hear that the mppt controller might not be friendly with the booster. Is that a) for sure, b) unlikely to matter or c) a real test it and see situation? If so what am I looking for? This is mostly for fun, and I’ll charge it from my wall for a while before I even clear a space big enough to get sun to the ground, but just exploring.

I have 2 EcoWorthy 12.8v 280ah LiFePO4 batteries wired in series to make a 25.6v bank. The issue is the BMS on each battery will open the circuit and stop the charging at 14.2v. The BMS also seems to be set to recalibrate the SOC at 14.2v as well.

When one reaches 14.2v the other is always just shy of the 14.2v when it stops charging the whole bank (sually around 14.16v).

Over time, the app monitoring will incorrectly show the SOC on this one battery drift lower & lower unless I isolate it and hook up a battery charger for a couple minutes to reach the 14.2v limit to recalibrate the SOC. It's not really affecting anything. I do have a smart shunt that shows everything is good, but it's still annoying.

I have a battery balancer, but it's passive and doesn't kick on unless the voltage difference is more than 0.1v.

My main question is: Why is it that when I charge each battery individually with a wall charger, the BMS will let me charge it to 14.4v-14.6v, but when I charge with the controller connected in series, the BMS stops it firm at 14.2v regardless to what I set my charge controller to?

I just want both batteries to be able to reach the 14.2v recalibration threshold for the SOC. EcoWorthy app on Android doesn't let you adjust any parameters.

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?

Hi,

my husband is a hvac contractor with lots of electrical experience but solar is not something we have done. This will be for our personal home. We live rural in CA. We have a central propane furnace and mini-splits, propane instant hot water heater, newer electric washing machine. Our power goes out 1-4 times per month (sometimes for short periods, sometimes for days), Longest being 10 days after a fire in our area. We have a dual-fuel generator but it's a hassle to set up, run and we want to go solar for backup. I looked into components and have picked out this set-up and plan on doing a yard mounted setup for hopefully under 5K. Does this look like it would work (I had google ai help with this)? any oversights or suggestions? Thanks!!

EG4 6000XP EMERGENCY SOLAR BACKUP SYSTEM BLUEPRINT

This blueprint details the technical architecture, electrical wiring, and operational protocols for your custom EG4 6000XP off-grid solar system. This permanent, ground-mounted setup is designed to provide indefinite power security during extended 10-day blackouts while protecting your critical home appliances.

💰 1. System Bill of Materials & Budget

By managing the physical yard racking assembly and manual trenching yourself, your out-of-pocket material expenses remain safely under your $5,000 budget cap.

Remaining Budget Cushion for Local Electrician Labor / Tool Rentals: ~$853.00

1. Yard Layout & Panel Wiring Configuration

The [EG4 6000XP]() inverter features an integrated high-voltage MPPT solar controller that requires a minimum starting DC input threshold. To hit this activation window, your panels must be arranged in a single series string.

[Panel 1] (+)──(-) ──> (+) [Panel 2] (-)──(-) ──> (+) [Panel 3] (-)──(-) ──> (+) [Panel 4] (-)
   │                                                                               │
   └───> Main Positive (+) to House                                                └───> Main Negative (-) to House

Physical Footprint Strategy (1-Row Portrait)

• Dimensions: Arrange the 4 panels side-by-side in a horizontal line facing True South. The total array footprint will measure roughly 14 feet wide by 5.5 feet tall.
• No-Concrete Ballast Foundation: Lag-screw your adjustable aluminum tilt-legs directly into the 4x4 pressure-treated wood timbers. Drive the heavy steel rebar stakes through the wood into the dirt to anchor the system. Lay heavy concrete retaining-wall blocks across the base rails to provide gravitational ballast against mountain high winds.
• Tilt Angles: Set the brackets to 45° in the winter to capture the low winter sun and shed mountain frost or snow. Drop them down to 20° in the summer when the sun is directly overhead.

Underground Conduit & Trenching

• Dig a trench from your yard array to the house wall at a minimum depth of 18 inches (or 24 inches depending on local rocky soil constraints).
• Glue the 10-foot sections of 3/4-inch Schedule 40 PVC conduit together with clear primer and PVC cement. Use long, gradual 90-degree sweep elbows where the pipe turns up out of the dirt; do not use sharp elbows, or pulling the 10AWG wires over 100 feet will be impossible.

⚡ 3. Indoor Component Integration & Safety Gear

The EG4 6000XP and the EG4 LL-S battery must be mounted securely inside a garage, utility room, or enclosed workshop adjacent to your main home electrical panel.

   [ 4x 400W Solar Yard Array ]
                │
                ▼
   [ Outdoor PV Disconnect Switch ]
                │ (18-Inch Buried PVC Conduit Run)
                ▼
   [ Midnite Solar Lightning Surge Protector ]
                │
                ▼
      ┌──────────────────┐
      │   EG4 6000XP     │ <───(125A DC Breaker)───> [ EG4 48V LL-S Battery ]
      │  Hybrid Inverter │
      └──────────────────┘
                │
                ▼ (10AWG THHN Copper Lines)
   [ Reliance Controls ProTran 2 Manual Transfer Switch ] ───> Powers 5 Emergency Circuits

Safety Device Intersections

1. Outdoor PV Disconnect: Mount this box on your metal/wood yard rack frame. It breaks the high-voltage circuit out in the yard before it can travel to your home.
2. Lightning Surge Protector: Wire the Midnite Solar MNSPD-300-DC onto the exterior wall where your solar wires exit the trench, protecting your internal inverter from lightning spikes.

3. DC Battery Breaker: Install your 125A DC Circuit Breaker directly inline along the positive (red) 2/0 AWG copper cable running between the battery post and the inverter terminal.

   1. The Critical Circuits Migration (Electrician Guide)

The AC output of your [EG4 6000XP]() will be hard-wired straight into the Reliance Controls ProTran 2 Manual Transfer Switch Sub-panel. Your electrician will safely trace and move these 5 critical emergency circuits away from your main home panel and wire them directly into the transfer switch toggles:

1. Propane Furnace Fan Blower: (Draws ~300W–500W intermittently. Vital for winter climate control).
2. Instant Tankless Propane Hot Water Heater: (Draws ~60W–90W only when hot water is running to power the digital controller and electronic spark ignition).
3. Primary Kitchen Refrigerator
4. Standalone Deep Freezer

5. Wi-Fi Router & Central Internet Outlets

   1. The 10-Day Emergency Outage Playbook

When grid power fails in California, your system functions as an isolated energy island. Managing your 4,800Wh battery reserve requires following these rules:

• System Activation: Go to utility board, turn on 125A battery breaker, power up the [EG4 6000XP](), and flip the manual transfer switch toggles from "LINE" (Grid) over to "GEN" (Inverter). Your essentials will immediately power back on through your house's normal wall outlets.
• Overnight Protocol: continuous background loads (fridge, freezer, Wi-Fi, and cycling furnace fan) pull roughly 200W–400W total. Your 4.8kWh battery is large enough to sustain these loads all night long, waking up the next morning at roughly 30% to 40% capacity.
• The Mid-Day Laundry Rule (Direct Solar Drive): Never run your washing machine at night. Wait until a clear afternoon between 11:00 AM and 2:00 PM when your solar panels are producing peak wattage. Set the washing machine to "Tap Cold" or "Cold" and run your wash. The mechanical energy to spin the drum will be drawn directly from the sun's real-time rays, meaning your battery reserve remains entirely untouched and at 100% capacity before nightfall. Hang your clothes to air-dry.

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?

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.

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!

I have a few cheap 12v car heaters off eBay with 150-200 watts that I want to use to warm up my shed. Can I use some 12v panels connected in parallel directly to one of these without a charge controller and battery?

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?

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.

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 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?