Remote Site Solar and Battery Storage: 7 Checks Before You Sign an EPever Quote

I'm the office administrator at a 60-person logistics company. I manage operational ordering across about 12 vendors — roughly $350,000 a year — and I report to both operations and finance. That means when a project goes sideways, both sides ask me why.

In early 2024 we added backup power to a remote depot with a cranky grid connection. That project pulled me into small-scale solar, and since then I've handled the procurement side of two more installations — possibly three, I'd have to check my email. I'm not an electrician. But sitting between an operations manager who wants it to "just work" and a finance director who wants a clean invoice has taught me which parts of a solar quote to push back on.

Here's the checklist I now run before signing off any remote-site solar or battery storage quote. Seven checks, roughly in the order I do them. It's a buyer's checklist, not an engineering document — but every item has caught something real.

Check 1 — Lock down the system architecture before you look at prices

This is the step I should have done first time around. I collected four quotes on our first depot project, compared the bottom-line numbers, and picked the middle one. What I didn't realize until install day was that two quotes were for fully off-grid systems and two were grid-tied hybrid systems with battery backup. Different products entirely. I'd been comparing a truck to a station wagon.

Before price is even discussed, get the installer to state the architecture in writing: fully off-grid, grid-tied with battery, or hybrid. That one answer drives everything downstream — inverter sizing, transfer switches, and what kind of charge controller the system can use. If the site has any grid connection, also ask whether the design uses a central inverter or micro inverters, and get that in writing too. I've been burned once already by comparing quotes that were never comparable.

Check 2 — Read the spec sheet for the charge controller, not the brochure

The epever solar charge controller came up most often in our installer's proposals, and it's a reasonable default for a small remote system. But the model number matters more than the brand.

I now ask for the actual spec sheet and check three things. First, MPPT or PWM — MPPT generally harvests more in variable conditions, but for a small array in full sun, PWM can be fine and cheaper. Second, rated charge current against the array's real output — installers sometimes size the controller for ideal lab conditions and forget that panel output drops in heat. Third, max PV input voltage against the string's actual open-circuit voltage. I once caught a quote where the controller's max input voltage sat below the panel string's open-circuit rating. The installer re-sized it. That twenty minutes paid for itself.

Check 3 — Confirm the battery chemistry and the EPever charge controller lithium settings

If your system uses a lithium battery — and nowadays that's most projects — the epever charge controller lithium settings are the part of the quote nobody thinks to ask about until something goes wrong.

A solar charge controller has to know how much voltage to push into the battery at each charging stage. For lead-acid that's broadly standard. For lithium iron phosphate (LiFePO4), the voltage setpoints are tighter, and getting them wrong shortens battery life.

The epever charge controller lithium settings usually include a "User" profile alongside the canned LiFePO4 profile. On our second install I asked which profile the installer used. "User," they said, "we always use User." That turned out to mean they'd typed in custom numbers without our battery manufacturer's charging spec in hand. We pushed back and had the installer align the profile to the battery data sheet — specific absorption voltage, float voltage, and low-temperature charge cutoff.

Even after the corrected settings were confirmed, I kept second-guessing for a couple of weeks. What if the profile got reset during a firmware update? What if the field tech used a different profile than the one in the spec? The battery came with a monitoring app, so I asked the installer to set up alerts for overvoltage and low-temperature charge cutoff. That ended up more valuable than the settings checklist itself — nothing has gone out of range since, and I can check it without opening a cabinet.

Check 4 — Weigh central inverter vs micro inverter, if the site is grid-tied

I've only had to consider central inverter vs micro inverter once, on a hybrid install at a warehouse with a decent grid connection. But the decision is big enough that it deserves its own line in any quote review.

Central inverters convert DC to AC for the whole array in one unit. They're simpler, usually cheaper on larger arrays, and easy to service — one box to swap if something fails. The catch: a single shaded or faulty panel can drag down the whole string, and if that one box dies, the system goes dark.

Micro inverters sit under each panel and convert per-panel. The obvious win is that shading or single-panel failure doesn't kill the system — you lose one panel's output, not the array. The trade-off is more units to install, more units to eventually replace, and a higher cost per watt upfront.

To be fair, the gap has narrowed. Some installers we talked to said micro inverters had gotten reliable enough that the replacement math was no longer the obvious argument it used to be. But for a remote site where I can't easily send someone to troubleshoot, I leaned toward fewer field-replaceable parts. That said, our array is fairly small — I'd probably think differently about a large commercial array where a shaded panel isn't a serious risk.

Check 5 — Vet the battery storage company, not just the name on the cabinet

What most people don't realize is that the brand on the cabinet is often not the company that made the cells. A well-known name on the enclosure might be an integrator that sources cells from one of the largest battery storage companies and assembles them with its own BMS and warranty.

So ask: who actually made the cells inside this li ion battery storage unit? Which battery management system is it, and who supports it? Does the integrator have a regional service presence, or is the warranty routed through the installer — who might not be around in 18 months?

I now ask for the cell manufacturer's name in writing and check the warranty term against what the installer actually offers. A ten-year battery warranty means nothing if the integrator's distribution footprint doesn't reach your site. Granted, most integrators are honest about this when asked directly — the trick is remembering to ask.

Check 6 — Calculate total cost of ownership, not the quoted total

A line-item total is not the cost of the project. On our second depot, the quote with the lowest line-item cost came out roughly $1,200 higher over two years once we added shipping, commissioning, the annual maintenance visit, and one replacement of a controller the installer had undersized.

Here's the framework I use now. Take the quoted total and add: shipping and freight (often buried in "miscellaneous"), commissioning and on-site programming, first-year maintenance, a realistic battery-replacement reserve, and a risk allowance for the installer coming back for warranty work.

I ran the four quotes from our second project through this. The cheapest quote — $8,400, give or take a few hundred — ran to about $9,600 once freight and commissioning were in. The quote at $9,100, higher on paper, was all-inclusive and landed around $9,300. Watching $8,400 turn into $9,600 is what finally sold the finance director on the higher-looking quote. (Should mention: we also counted the cost of the depot losing power during the install weekend — roughly a day of overtime for the on-site crew.)

Time cost is the part that never makes it onto a quote. Approving a cheap quote that needs three follow-up visits costs you the time to chase those visits, and it costs your operations manager confidence in your judgment. That's a TCO line item too, even if nobody writes it down. At least, that's been my experience in four quotes so far.

Check 7 — Walk the warranty and RMA process before signing

The last check is the one most likely to get skipped when the schedule is tight. I know because I skipped it — on our first project, with a two-day window to approve before the install crew's schedule dropped us into a six-week wait. There was no time to push back on the warranty terms, so I signed the standard version.

Nothing has failed yet. But I've since learned to run the process before signing: who do I call if the epever solar charge controller fails in month 14? Does the installer handle the RMA, or do I? What's the typical replacement lead time? Do they stock spares locally, or does everything route through a warehouse four states away?

For a remote site, a three-week RMA turnaround is a three-week outage. That's a cost, even if it isn't on the quote. Getting a written RMA process — names, phone numbers, lead times — is my final checklist item.

What I'd flag to anyone starting this process

Two things I'd tell my past self. First, the architecture question in Check 1 isn't optional housekeeping — it's the check that makes every other comparison valid. Skip it, and you will eventually compare quotes for two different systems and pick the wrong one. Second, the lithium settings and battery-cell questions feel like engineering details, but they're the difference between a battery that lasts its rated cycles and one that quietly ages out two years early.

The rest of the checklist is mostly about not letting a good-looking quote hide an extra line. That's the part finance will thank you for — and the part your operations manager will thank you for a year later when nobody has had to drive out to the depot because the controller tripped.