What goes into a proposal for a solar plant
A commercial proposal sells a solution, not panels. What to put in it so the client understands what they pay for and can compare options — and what to leave out.
A client gets several proposals from different installers and compares them in the evening at the kitchen table. The cheapest does not always win. Often the winner is the one that is clear to read. Below is what is worth putting into a proposal for a solar plant, and why.
1. Who is offering
The company name, logo, contacts, the proposal's number and date. Number proposals in sequence within the year — it is easier for you and the client to refer to a specific version. In Solispec the company profile and logo are set once, and the number is assigned automatically.
2. For whom and where
The client's name, the site's address or coordinates, the plant type: on a roof, on the ground, on a flat roof. Yield depends on the place, and the client should see that you calculated their site.
3. Equipment — with models, not "10 kW of panels"
- panels: model, power, count;
- inverter: model, type (grid-tied or hybrid), power;
- battery, if any: model, capacity, count;
- electrics: DC and AC protection, cables.
Specific models let the client compare proposals. "10 kW of panels" cannot be compared.
4. The structure — checked
The mounting is often hidden in one line, "mounting system". Yet it decides whether the plant survives its first winter. It is good when the proposal rests on a structural calculation to the norms — loads per ДБН В.1.2-2, a check of the profiles and the nodes.
In Solispec no proposal is made for a design that failed its checks. You cannot send a client an offer for a structure that cannot be built.
5. An estimate you can read
Split the price into clear parts:
- equipment;
- structure and fixings;
- electrical materials;
- labour;
- delivery.
State separately whether VAT is included. You need not show the margin, but the total must add up from the lines.
6. Yield — with a source
"The plant will make N kWh a year" without a source does not convince. Say where the figure comes from. Solispec shows two estimates in the proposal: from the formula and from PVGIS 5.3 data (the EU Joint Research Centre) for your panels' orientation and tilt at that exact spot. If the figures differ noticeably, that is a reason to check the inputs.
7. Payback — with its assumptions
Payback depends on the tariff, the share of self-consumption and the export price. Write these assumptions into the proposal. If the client changes the tariff in their head, they should know what changes in the result. The load profile (family, heat pump, EV, business) is an assumption too, and it is worth saying so.
8. Options side by side
The question "and with a battery, how much?" will come anyway. Better answer it in the proposal itself. Three options side by side — grid-tied, hybrid + battery, hybrid + battery + generator — show the client the price of autonomy. They choose themselves instead of asking you to recalculate.
Do not make up the price of what you do not supply. If the client buys the generator, say so.
9. How to accept
A PDF gets lost in a messenger. A link to an online proposal page works better: the client opens it on a phone, sees the options, picks one and accepts. You see that the proposal was viewed and which option was chosen.
What does not belong in a proposal
- promises that are not in the calculation ("pays back in two years" with no figures);
- "with a margin" specs that the datasheet does not confirm;
- small print that changes what is offered.
In short
A good proposal answers the client's five questions: what do I get, what does it cost, how much will it produce, when will it pay back, and what if I choose another option. Everything else is layout.